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Bibliography on: Biofilm

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ESP: PubMed Auto Bibliography 21 Jun 2021 at 01:31 Created: 


Wikipedia: Biofilm A biofilm is any group of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular polymeric substances (EPS). The EPS components are produced by the cells within the biofilm and are typically a polymeric conglomeration of extracellular DNA, proteins, and polysaccharides. Because they have three-dimensional structure and represent a community lifestyle for microorganisms, biofilms are frequently described metaphorically as cities for microbes. Biofilms may form on living or non-living surfaces and can be prevalent in natural, industrial and hospital settings. The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by contrast, are single-cells that may float or swim in a liquid medium. Biofilms can be present on the teeth of most animals as dental plaque, where they may cause tooth decay and gum disease. Microbes form a biofilm in response to many factors, which may include cellular recognition of specific or non-specific attachment sites on a surface, nutritional cues, or in some cases, by exposure of planktonic cells to sub-inhibitory concentrations of antibiotics. When a cell switches to the biofilm mode of growth, it undergoes a phenotypic shift in behavior in which large suites of genes are differentially regulated.

Created with PubMed® Query: biofilm[title] NOT 28392838[PMID] NOT 31293528[PMID] NOT 29372251[PMID] NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)


RevDate: 2021-06-15

Ji B, Zhang H, Zhou L, et al (2021)

Effect of the rapid increase of salinity on anoxic-oxic biofilm reactor for treatment of high-salt and high-ammonia-nitrogen wastewater.

Bioresource technology, 337:125363 pii:S0960-8524(21)00703-3 [Epub ahead of print].

The washing wastewater from the desulfuration and denitration of power plants has high salt (chloride and sulfate) and ammonia-nitrogen concentrations and is difficult to treat using microbiological methods. A novel anoxic/oxic biofilm process was developed to remove ammonia from wastewater. Three rapid strategies (sulfate concentration was increased from 0 to 60 g/L in 6, 13, and 22 days (R1, R2, and R3, respectively)) were applied and produced biofilm with the same nitrification capacity as slow strategies (100-203 days). Excessive organics inhibited the nitrification capacity of the biofilm. R1 excelled at ammonia removal (from 30% to 95%, 70 mg/(L·d), with an effluent ammonia concentration of 4 mg/L) at 60 g/L salinity after the organic load was reduced. The content of extracellular polymeric substances in biofilm depended on its capacity to remove organics. Pseudomonas and Thauera were enriched in the three reactors. Controlling the organic load might prevent the sulfur cycle.

RevDate: 2021-06-15

Primo MGB, Tipple AFV, Costa DM, et al (2021)

Biofilm accumulation in new flexible gastroscope channels in clinical use.

Infection control and hospital epidemiology pii:S0899823X21000994 [Epub ahead of print].

OBJECTIVE: Assess the accumulation of protein and biofilm on the inner surfaces of new flexible gastroscope (FG) channels after 30 and 60 days of patient use and full reprocessing.

DESIGN: Clinical use study of biofilm accumulation in FG channels.

SETTING: Endoscopy service of a public hospital.

METHODS: First, we tested an FG in clinical use before the implementation of a revised reprocessing protocol (phase 1 baseline; n = 1). After replacement of the channels by new ones and the implementation of the protocol, 3 FGs were tested after 30 days of clinical use (phase 2; n = 3) and 3 FGs were tested after 60 days of clinical use (phase 3; n = 3), and the same FGs were tested in phase 2 and 3. Their biopsy, air, water, and air/water junction channels were removed and subjected to protein testing (n = 21), bacteriological culture (n = 21), and scanning electron microscopy (SEM) (n = 28). Air-water junction channels fragments were subjected to SEM only.

RESULTS: For the FGs, the average number of uses and reprocessing cycles was 60 times. Extensive biofilm was detected in air, water, and air-water junction channels (n = 18 of 28). All channels (28 of 28) showed residual matter, and structural damage was identified in most of them (20 of 28). Residual protein was detected in the air and water channels of all FG evaluated (phases 1-3), except for 1 air channel from phase 2. Bacteria were recovered from 8 of 21 channels, most air or water channels.

CONCLUSIONS: The short time before damage and biofilm accumulation in the channels was evident and suggests that improving the endoscope design is necessary. Better reprocessing methods and channel maintenance are needed.

RevDate: 2021-06-15

Willett JLE, Dale JL, Kwiatkowski LM, et al (2021)

Comparative Biofilm Assays Using Enterococcus faecalis OG1RF Identify New Determinants of Biofilm Formation.

mBio [Epub ahead of print].

Enterococcus faecalis is a common commensal organism and a prolific nosocomial pathogen that causes biofilm-associated infections. Numerous E. faecalis OG1RF genes required for biofilm formation have been identified, but few studies have compared genetic determinants of biofilm formation and biofilm morphology across multiple conditions. Here, we cultured transposon (Tn) libraries in CDC biofilm reactors in two different media and used Tn sequencing (TnSeq) to identify core and accessory biofilm determinants, including many genes that are poorly characterized or annotated as hypothetical. Multiple secondary assays (96-well plates, submerged Aclar discs, and MultiRep biofilm reactors) were used to validate phenotypes of new biofilm determinants. We quantified biofilm cells and used fluorescence microscopy to visualize biofilms formed by six Tn mutants identified using TnSeq and found that disrupting these genes (OG1RF_10350, prsA, tig, OG1RF_10576, OG1RF_11288, and OG1RF_11456) leads to significant time- and medium-dependent changes in biofilm architecture. Structural predictions revealed potential roles in cell wall homeostasis for OG1RF_10350 and OG1RF_11288 and signaling for OG1RF_11456. Additionally, we identified growth medium-specific hallmarks of OG1RF biofilm morphology. This study demonstrates how E. faecalis biofilm architecture is modulated by growth medium and experimental conditions and identifies multiple new genetic determinants of biofilm formation. IMPORTANCE E. faecalis is an opportunistic pathogen and a leading cause of hospital-acquired infections, in part due to its ability to form biofilms. A complete understanding of the genes required for E. faecalis biofilm formation as well as specific features of biofilm morphology related to nutrient availability and growth conditions is crucial for understanding how E. faecalis biofilm-associated infections develop and resist treatment in patients. We employed a comprehensive approach to analysis of biofilm determinants by combining TnSeq primary screens with secondary phenotypic validation using diverse biofilm assays. This enabled identification of numerous core (important under many conditions) and accessory (important under specific conditions) biofilm determinants in E. faecalis OG1RF. We found multiple genes whose disruption results in drastic changes to OG1RF biofilm morphology. These results expand our understanding of the genetic requirements for biofilm formation in E. faecalis that affect the time course of biofilm development as well as the response to specific nutritional conditions.

RevDate: 2021-06-15

Wang H, Christiansen DE, Mehraeen S, et al (2020)

Winning the fight against biofilms: the first six-month study showing no biofilm formation on zwitterionic polyurethanes.

Chemical science, 11(18):4709-4721.

Biofilms have been a long-standing challenge for healthcare, water transport, and many other industries. They lead to bacterial growth and infections in animals, food products, and humans, cause premature removal of the implanted materials or devices from patients, and facilitate fouling and corrosion of metals. Despite some published and patented methods on minimizing the effects of biofilms for a short period (less than two weeks), there exists no successful means to mitigate or prevent the long-term formation of biofilms. It is even more challenging to integrate critical anti-fouling properties with other needed physical and chemical properties for a range of applications. In this study, we developed a novel approach for combining incompatible, highly polar anti-fouling groups with less polar, mechanically modifying groups into one material. A multifunctional carboxybetaine precursor was designed and introduced into polyurethane. The carboxybetaine precursors undergo rapid, self-catalyzed hydrolysis at the water/material interface and provide critical anti-fouling properties that lead to undetectable bacterial attachment and zero biofilm formation after six months of constant exposure to Pseudomonas aeruginosa and Staphylococcus epidermidis under the static condition in a nutrient-rich medium. This zwitterionic polyurethane is the first material to demonstrate both critical anti-biofilm properties and tunable mechanical properties and directly validates the unproven anti-fouling strategy and hypothesis for biofilm formation prevention. This approach of designing 'multitasking materials' will be useful for the development of next generation anti-fouling materials for a variety of applications.

RevDate: 2021-06-14

Giorgi-Pérez AM, Arboleda-Ordoñez AM, Villamizar-Suárez W, et al (2021)

Biofilm formation and its effects on microbiologically influenced corrosion of carbon steel in oilfield injection water via electrochemical techniques and scanning electron microscopy.

Bioelectrochemistry (Amsterdam, Netherlands), 141:107868 pii:S1567-5394(21)00131-6 [Epub ahead of print].

In this study, changes in the electrochemical conditions of oil fields caused by biofilms with sulfate-reducing bacteria have been studied as they promote localized pitting damage, reservoir souring problems, and many other processes including well plugging that lead to increased production costs. Biofilm formation and its effects on 1020 carbon steel surfaces were evaluated in a discontinuous electrochemical reactor by using a bacterial consortium isolated from the injection water of a Colombian oil field. Sulfide concentration and pH values were observed to decrease, which was consistent with the exponential planktonic sulfate-reducing bacterial growth. The formation of a biofilm that adheres to a porous layer of corrosion products was identified using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The morphology of the films revealed the presence of the biofilm and corrosion product crystals. Open circuit potential presented a negative shift in the potential during the first 24 h in a biotic cell. Electrochemical impedance spectroscopy showed a change in the behavior of the resistive zone for both systems, a charge transfer trend in the abiotic cell, and a transformation of the charge transfer process to a diffusive process in the biotic cell after 48 h. The polarization resistance showed its lowest resistivity 74.95 Ω·cm-2 during the first 48 h, while the corrosion rate was estimated as 3.37 mpy. This research contributes to the understanding of corrosion mechanisms in the metal-solution interface via detailed monitoring of biofilm growth.

RevDate: 2021-06-14

Ma F, Zhou H, Yang Z, et al (2021)

Gene expression profile analysis and target gene discovery of Mycobacterium tuberculosis biofilm.

Applied microbiology and biotechnology [Epub ahead of print].

Tuberculosis (TB) caused by Mycobacterium tuberculosis (M. tuberculosis) is a fatal infectious disease to human health, and the drug tolerance and immune evasion of M. tuberculosis were reported to be related to its biofilm formation; however, the difficulty of M. tuberculosis biofilm culture and its unknown global mechanism impede its further research. Here, we developed a modified in vitro M. tuberculosis biofilm model with shorter culture time. Then we used Illumina RNA-seq technology to determine the global gene expression profile of M. tuberculosis H37Rv biofilms. Over 437 genes are expressed at significantly different levels in biofilm cells than in planktonic cells; among them, 153 were downregulated and 284 were upregulated. Go enrichment analysis and KEGG pathway analysis showed that genes involved in biosynthesis and metabolism of sulfur metabolism, steroid degradation, atrazine degradation, mammalian cell entry protein complex, etc. are involved in M. tuberculosis biofilm cells. Especially, ATP-binding cassette (ABC) transporters Rv1217c and Rv1218c were significantly upregulated in biofilm, whereas efflux pump inhibitors (EPIs) piperine and 1-(1-naphthylmethyl)-piperazine (NMP) inhibited biofilm formation and the expression of the Rv1217c and Rv1218c genes in a concentration-dependent manner, respectively, indicating Rv1217c and Rv1218c are potential target genes of M. tuberculosis biofilm. This study is the first RNA-Seq-based transcriptome profiling of M. tuberculosis biofilms and provides insights into a potential strategy for M. tuberculosis biofilm inhibition. KEY POINTS: • Characterize M. tuberculosis transcriptomes in biofilm cells by RNA-seq. • Inhibit the expression of Rv1217c and Rv1218c repressed biofilm formation.

RevDate: 2021-06-15

Smolarz M, Zawrotniak M, Satala D, et al (2021)

Extracellular Nucleic Acids Present in the Candida albicans Biofilm Trigger the Release of Neutrophil Extracellular Traps.

Frontiers in cellular and infection microbiology, 11:681030.

Neutrophils, the first line of the host's defense, use a variety of antimicrobial mechanisms to fight invading pathogens. One of the most crucial is the production of neutrophil extracellular traps (NETs) in the process called NETosis. The unique structure of NETs effectively inhibits the spread of pathogens and ensures their exposure to a high concentration of NET-embedded antimicrobial compounds. NETosis strategy is often used by the host to defend against fungal infection caused by Candida albicans. In immunocompromised patients, this microorganism is responsible for developing systemic fungal infections (candidiasis). This is correlated with the use of a vast array of virulence factors, leading to the acquisition of specific resistance to host defense factors and available drug therapies. One of the most important features favoring the development of drug resistance is a C. albicans ability to form biofilms that protect fungal cells mainly through the production of an extracellular matrix (ECM). Among the main ECM-building macromolecules extracellular nucleic acids have been identified and their role is probably associated with the stbilization of the biofilm structure. The complex interactions of immune cells with the thick ECM layer, comprising the first line of contact between these cells and the biofilm structure, are still poorly understood. Therefore, the current studies aimed to assess the release of extracellular nucleic acids by C. albicans strains at different stages of biofilm formation, and to determine the role of these molecules in triggering the NETosis. We showed for the first time that fungal nucleic acids, purified directly from mature C. albicans biofilm structure or obtained from the whole fungal cells, have the potential to induce NET release in vitro. In this study, we considered the involvement of TLR8 and TLR9 in NETosis activation. We showed that DNA and RNA molecules initiated the production of reactive oxygen species (ROS) by activation of the NADPH oxidase complex, essential for ROS-dependent NETosis. Furthermore, analysis of the cell migration showed that the nucleic acids located in the extracellular space surrounding the biofilm may be also effective chemotactic factors, driving the dynamic migration of human neutrophils to the site of ongoing fungal infection.

RevDate: 2021-06-15

El Othmany R, Zahir H, Ellouali M, et al (2021)

Current Understanding on Adhesion and Biofilm Development in Actinobacteria.

International journal of microbiology, 2021:6637438.

Biofilm formation and microbial adhesion are two related and complex phenomena. These phenomena are known to play an important role in microbial life and various functions with positive and negative aspects. Actinobacteria have wide distribution in aquatic and terrestrial ecosystems. This phylum is very large and diverse and contains two important genera Streptomyces and Mycobacteria. The genus Streptomyces is the most biotechnologically important, while the genus Mycobacteria contains the pathogenic species of Mycobacteriaceae. According to the literature, the majority of studies carried out on actinomycetes are focused on the detection of new molecules. Despite the well-known diversity and metabolic activities, less attention has been paid to this phylum. Research on adhesion and biofilm formation is not well developed. In the present review, an attempt has been made to review the literature available on the different aspects on biofilm formation and adhesion of Actinobacteria. We focus especially on the genus Streptomyces. Furthermore, a brief overview about the molecules and structures involved in the adhesion phenomenon in the most relevant genus is summarized. We mention the mechanisms of quorum sensing and quorum quenching because of their direct association with biofilm formation.

RevDate: 2021-06-15

Hall DC, Palmer P, Ji HF, et al (2021)

Bacterial Biofilm Growth on 3D-Printed Materials.

Frontiers in microbiology, 12:646303.

Recent advances in 3D printing have led to a rise in the use of 3D printed materials in prosthetics and external medical devices. These devices, while inexpensive, have not been adequately studied for their ability to resist biofouling and biofilm buildup. Bacterial biofilms are a major cause of biofouling in the medical field and, therefore, hospital-acquired, and medical device infections. These surface-attached bacteria are highly recalcitrant to conventional antimicrobial agents and result in chronic infections. During the COVID-19 pandemic, the U.S. Food and Drug Administration and medical officials have considered 3D printed medical devices as alternatives to conventional devices, due to manufacturing shortages. This abundant use of 3D printed devices in the medical fields warrants studies to assess the ability of different microorganisms to attach and colonize to such surfaces. In this study, we describe methods to determine bacterial biofouling and biofilm formation on 3D printed materials. We explored the biofilm-forming ability of multiple opportunistic pathogens commonly found on the human body including Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus to colonize eight commonly used polylactic acid (PLA) polymers. Biofilm quantification, surface topography, digital optical microscopy, and 3D projections were employed to better understand the bacterial attachment to 3D printed surfaces. We found that biofilm formation depends on surface structure, hydrophobicity, and that there was a wide range of antimicrobial properties among the tested polymers. We compared our tested materials with commercially available antimicrobial PLA polymers.

RevDate: 2021-06-13

Eladawy M, El-Mowafy M, Adel El-Sokkary MM, et al (2021)

Antimicrobial resistance and virulence characteristics in ERIC-PCR typed biofilm forming isolates of P. aeruginosa.

Microbial pathogenesis pii:S0882-4010(21)00314-4 [Epub ahead of print].

Pseudomonas aeruginosa is a serious pathogen particularly in immunocompromised patients. In this work, 103 clinical isolates of P. aeruginosa were collected and classified into weak, moderate, and strong biofilm producers according to their biofilm forming abilities via tissue culture plate method. The antimicrobial resistance and the presence of different virulence genes were investigated via disc diffusion method and polymerase chain reaction respectively. Moreover, ERIC-PCR typing was performed to investigate the genetic diversity among the clinical isolates. No significant correlation was observed between biofilm formation and resistance to each antimicrobial agent. Similar observation was detected concerning the multidrug resistance and biofilm formation. Regarding virulence genes, algD gene was harbored by all isolates (100%). Only pelA and phzM were significantly prevalent in strong biofilm producer. Additionally, the mean virulence score was higher strong biofilm producers (9.33) than moderate (8.62) and weak (7) biofilm producers. Moreover, there was a significant correlation between the overall virulence score of the isolates and its ability to form biofilm. ERIC-PCR genotyping revealed the presence of 99 different ERIC patterns based on 70% similarity, and the different ERIC patterns were categorized into 8 clusters. 100% similarity indicates the possibility of cross-colonization in P. aeruginosa infections.

RevDate: 2021-06-12

Bhowmick T, Sen G, Mukherjee J, et al (2021)

Assessing the effect of herbicide diuron on river biofilm: A statistical model.

Chemosphere, 282:131104 pii:S0045-6535(21)01576-9 [Epub ahead of print].

River biofilm communities are the first ones to be exposed to all toxic discharges received via run off from agricultural fields. Hence, changes in river biofilm community structure and growth pattern are considered as indicator of overall health of lotic ecosystem. Toxicants have effect on biofilm biomass, photosynthetic efficiency and chlorophyll a concentrations. Mathematical models may be applied to estimate the overall vigor of riverine ecosystems considering biofilms as indicators. Herein, previous empirical data of Ricart et al. (2009) on long term effects of environmentally relevant concentrations of diuron on biofilm communities of the River Llobregat, Spain was considered as our model inputs. Our objective is to understand the influence of diuron, chlorophyll a concentrations and photosynthetic efficiency on biovolume using a statistical model. The non-linear relationships between biovolume (dependent variable) and diuron, chlorophyll a concentrations and photosynthetic efficiency (independent variables) were represented by constructing three separate basis functions based on day 8 empirical data. Biovolume, due to nonlinear influence as yielded by the basis functions were used in a multiple linear regression model to estimate the net biovolume. Model validation was done based on day 29 empirical data. The experimentally determined biovolume and our model estimated biovolume showed similar trends. Also, diuron and photosynthetic efficiency had significant (p < 0.05) influence on biovolume. Since, the predominance of diatoms as biofilms within periphytic layers is very common in lotic systems, estimation of changes in diatom biovolume will be significant to assess the effect of herbicides. Diatom biovolume of any day (for example day 22) mentioned in the experimental study may be determined by this model, without the requirement of tedious manual biovolume calculation. Our model will be useful in numerous other studies undertaken on the toxic effect of pollutants on biofilms to quickly and accurately estimate the biofilm biovolume.

RevDate: 2021-06-12

Yadav N, Govindwar SP, Rane N, et al (2021)

Insights on the role of periphytic biofilm in synergism with Iris pseudacorus for removing mixture of pharmaceutical contaminants from wastewater.

Journal of hazardous materials, 418:126349 pii:S0304-3894(21)01313-3 [Epub ahead of print].

The potential of Iris pseudacorus and the associated periphytic biofilm for biodegradation of two common pharmaceutical contaminants (PCs) in urban wastewater was assessed individually and in consortium. An enhanced removal for sulfamethoxazole (SMX) was achieved in consortium (59%) compared to individual sets of I. pseudacorus (50%) and periphytic biofilm (7%) at concentration of 5 mg L-1. Conversely, individual sets of periphytic biofilm (77%) outperformed removal of doxylamine succinate (DOX) compared to individual sets of I. pseudacorus (59%) and consortium (67%) at concentration of 1 mg L-1. Enhanced relative abundance of microflora containing microalgae (Sellaphora, Achnanthidium), rhizobacteria (Acidibacter, Azoarcus, Thioalkalivibrio), and fungi (Serendipita) in periphytic biofilm was observed after treatment. SMX treatment for five days elevated cytochrome P450 enzymes' expressions, including aniline hydroxylase (48%) and aminopyrine N-demethylase (54%) in the periphytic biofilm. Nevertheless, I. pseudacorus showed 175% elevation of aniline hydroxylase along with other biotransformation enzymes, such as peroxidase (629%), glutathione S-transferase (514%), and dichloroindophenol reductase (840%). A floating bed phytoreactor planted with I. pseudacorus and the periphytic biofilm consortium removed 67% SMX and 72% DOX in secondary wastewater effluent. Thus, the implementation of this strategy in constructed wetland-based treatment could be beneficial for managing effluents containing PCs.

RevDate: 2021-06-12

Marcato RA, Garbelini CCD, Danelon M, et al (2021)

In situ evaluation of 200 ppm fluoride toothpaste content trimetaphosphate, xylitol and erythritol on enamel demineralization and dental biofilm.

Journal of dentistry pii:S0300-5712(21)00145-7 [Epub ahead of print].

OBJECTIVE: To evaluate the effect of low-fluoride (F-) toothpaste and sodium trimetaphosphate (TMP) associated with xylitol and erythritol (XE) on enamel demineralization and biofilm composition.

METHODS: This crossover double-blind in situ study consisted of five phases (seven days each) and 14 volunteers who wore oral appliances containing four enamel bovine blocks. The cariogenic challenge was performed by 30% sucrose solution (6x/day). The toothpaste treatments (3x/day) were as follows: placebo (no F-/TMP/XE); 200 ppm F- (NaF) (200F); 1,100 ppm F- (1100F); 16% Xylitol and 4% Erythritol (XE); and 200 ppm F-, 0.2% TMP, 16% xylitol, and 4% erythritol (200F-TMP-XE). Percentage of surface hardness loss (%SH) and integrated loss of subsurface hardness (ΔKHN), and calcium (Ca2+), phosphate (PO43-), and F- on enamel and biofilm were determined; as well as insoluble extracellular polysaccharide (EPS).

RESULTS: XE and 1100F groups showed no different for the %SH and ΔKHN values (p = 0.220 and p = 0.886), and the 200F-TMP-XE group had the lowest mineral loss (p < 0.001). Ca2+ and PO43- in the enamel showed the highest values (p < 0.001) for the 200F-TMP-XE group. Higher values of F- in the enamel and biofilm were observed for the 1100F group (p < 0.001). There was no difference for Ca2+ (p = 1.00) and EPS (p =0.918) values between XE and 200-TMP-XE groups in the biofilm, but their values were higher and lower than the 1100F (p = 0.002 and p = 0.029), respectively.

CONCLUSIONS: 200F-TMP-XE promoted a greater protective effect against enamel demineralization and significantly affected the composition of biofilm formed in situ compared to 1100F toothpaste.

CLINICAL SIGNIFICANCE: Low-F- toothpaste containing TMP and polyols can be considered an effective and safe measure to improve the oral health of individuals, especially patients with high caries activity.

RevDate: 2021-06-12

Birk SE, Serioli L, Cavallo V, et al (2021)

Enhanced Eradication of Mucin-Embedded Bacterial Biofilm by Locally Delivered Antibiotics in Functionalized Microcontainers.

Macromolecular bioscience [Epub ahead of print].

Bacterial biofilm-related infections are difficult to eradicate and require repeated treatments with high doses of antibiotics. Thus, there is an urgent need for new treatment strategies that minimize the use of antibiotics while enhancing biofilm eradication. Functionalized reservoir-based microdevices, such as, microcontainers (MCs), offer, high drug loading capacity, mucus embedment, and tuneable drug release. Here, MCs are loaded with the antibiotic ciprofloxacin (CIP), and sealed with a lid consisting of chitosan (CHI) and a mucolytic agent, N-acetylcysteine (NAC). It is found that CHI and NAC work synergistically, showing improved mucoadhesive and mucolytic properties. To better mimic the in vivo habitat of Pseudomonas aeruginosa (P. aeruginosa), the biofilm is grown in a mucin-containing medium on a newly developed centrifugal microfluidic system. The CHI/NAC coated MCs improve eradication of biofilm (88.22 ± 2.89%) compared to CHI-coated MCs (72.68 ± 3.73%) or bolus injection (39.86 ± 13.28%). The findings suggest that MCs are significantly more efficient than a bolus treatment. Furthermore, CHI/NAC functionalized MCs kill most of the biomass already after 5 h (80.75 ± 3.50%), mainly due to a fast drug release. This is the first time that CHI/NAC has been combined as a coating to explore mucolytic properties on bacterial biofilms.

RevDate: 2021-06-12

Ozer E, Yaniv K, Chetrit E, et al (2021)

An inside look at a biofilm: Pseudomonas aeruginosa flagella biotracking.

Science advances, 7(24): pii:7/24/eabg8581.

The opportunistic pathogen, Pseudomonas aeruginosa, a flagellated bacterium, is one of the top model organisms for biofilm studies. To elucidate the location of bacterial flagella throughout the biofilm life cycle, we developed a new flagella biotracking tool. Bacterial flagella were site-specifically labeled via genetic code expansion. This enabled us to track bacterial flagella during biofilm maturation. Live flagella imaging revealed the presence and synthesis of flagella throughout the biofilm life cycle. To study the possible role of flagella in a biofilm, we produced a flagella knockout strain and compared its biofilm to that of the wild-type strain. Results showed a one order of magnitude stronger biofilm structure in the wild type in comparison with the flagella knockout strain. This suggests a possible structural role for flagella in a biofilm, conceivably as a scaffold. Our findings suggest a new model for biofilm maturation dynamic which underscores the importance of direct evidence from within the biofilm.

RevDate: 2021-06-11

Vitorino I, Albuquerque L, Wiegand S, et al (2021)

Corrigendum to "Alienimonas chondri sp. nov., a novel planctomycete isolated from the biofilm of the red alga Chondrus crispus" [Syst. Appl. Microbiol. 43 (2020) 126083].

RevDate: 2021-06-11

Haiat A, Ngo HC, Samaranayake LP, et al (2021)

The effect of the combined use of silver diamine fluoride and potassium iodide in disrupting the plaque biofilm microbiome and alleviating tooth discoloration: A systematic review.

PloS one, 16(6):e0252734 pii:PONE-D-21-05217.

Silver diamine fluoride (SDF) is used in minimally invasive dentistry for arresting dental caries. However, discoloration of teeth is a significant side effect that has limited the use of SDF. Hence, the application of potassium iodide (KI) following SDF has been proposed to ameliorate the staining. Although antimicrobial activity is one of the major mechanisms of the caries-arresting effect of SDF, the antimicrobial potency of SDF/KI combination is unclear. Thus, the primary objective of this systematic review was to appraise the studies on the antimicrobial efficacy of SDF/KI combination on cariogenic microbes. The secondary objective was to summarize the evidence on the potential of KI in reducing the discoloration associated with the application of SDF. Electronic databases of Medline via PubMed, Cochrane Library, Web of Science, and EBSCO host were searched for English language manuscripts from January 2005 to 15th November 2020. The reference lists of these manuscripts were manually searched for additional studies. Twelve studies were included in the final analysis, seven of which have investigated the antimicrobial efficacy of SDF/KI, and the rest have examined the anti-staining potential of KI. The exploratory findings from the reviewed articles revealed the promising antimicrobial potential of SDF/KI on cariogenic microbes associated with dentine caries. There is, however, contradictory evidence on the effect of SDF/KI on tooth color. The reviewed in-vitro studies indicated significant effectiveness of KI in preventing staining. A clinical trial on primary dentition showed 25% reduction in the incidence of staining by SDF after applying KI, while a clinical study on root caries in adults showed no significant effect. Within the methodological limitations of this review, we conclude that for arresting dental caries, SDF could be combined with KI, as there may be a lower likelihood of staining. Further, well-designed clinical trials on the antimicrobial and anti-staining effect of SDF/KI are needed to obtain more robust evidence.

RevDate: 2021-06-11

Asmarz HY, Magrin GL, Prado AM, et al (2021)

Evaluation of Removal Torque and Internal Surface Alterations in Frictional Morse Taper Connections After Mechanical Loading Associated or Not with Oral Biofilm.

The International journal of oral & maxillofacial implants, 36(3):492-501.

PURPOSE: To evaluate the abutment removal torque and the morphologic aspects of wear in frictional Morse taper connections after axial loading with or without biofilm immersion.

MATERIALS AND METHODS: Thirty sets of Morse taper implants and prosthetic abutments were divided into six groups based on the number of mechanical loading cycles and immersion in biofilm derived from human saliva: without load, without biofilm; without load, with biofilm; 100,000 cycles of load, without biofilm; 100,000 cycles of load, with biofilm; 500,000 cycles of load, without biofilm; and 500,000 cycles of load, with biofilm. Mechanical loading was applied at a force of 80 ± 15 N with a frequency of 2 Hz for 100,000 or 500,000 cycles. After removal torque evaluation, the internal surface of the implants was evaluated by scanning electron microscopy and optical profilometer. The results were statistically analyzed at a significance level of P = .05.

RESULTS: Overall, the removal torque increased for samples submitted to loading (100,000 cycles of load, without biofilm = 83.8 ± 15.8 Ncm; 100,000 cycles of load, with biofilm = 160.6 ± 16.2 Ncm; 500,000 cycles of load, without biofilm = 147.0 ± 29.3 Ncm; 500,000 cycles of load, with biofilm = 154.5 ± 14.0 Ncm) compared to samples without loading (without load, without biofilm = 23.0 ± 9.4 Ncm; without load, with biofilm = 27.2 ± 7.5 Ncm). The removal torque was not different between groups that received the same number of loading cycles and varied on biofilm exposure (P > .05). However, samples immersed in biofilm showed higher values of removal torque. Surface analysis revealed that the damage on the internal surface of implants was lower in samples not submitted to cyclic mechanical loading (P < .05) independently of immersion in biofilm medium.

CONCLUSION: Cyclic mechanical load on the frictional implant-abutment connection of Morse taper implants increased the removal torque of abutments. The findings of this research suggest that the presence of biofilm can potentially increase the removal torque in frictional Morse taper connections, although more studies are recommended to support this affirmation. Oral biofilm did not interfere with the presence of wear areas along the internal surface of Morse taper implants but increased the roughness values.

RevDate: 2021-06-11

Jiang X, Ren S, Geng Y, et al (2021)

Role of the VirSR-VirAB system in biofilm formation of Listeria monocytogenes EGD-e.

Food research international (Ottawa, Ont.), 145:110394.

The ability of Listeria monocytogenes, an important foodborne pathogen, to form biofilms in food processing environments leads to increased opportunity for contamination of food products, which is a major concern for food safety. In this study, the role of a complex system composed of the VirSR two-component signal transduction system (TCS) and the ATP-binding cassette (ABC) transporter VirAB in biofilm formation of L. monocytogenes EGD-e was investigated. Biofilm formation was measured using the microplate assay with crystal violet staining, confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), and attachment and swarming motility were compared between strain EGD-e and its isogenic deletion mutants. Additionally, the relative expression levels of genes associated with the early steps of biofilm development in the wild-type and mutant strains were also determined by RT-qPCR. Results from microplate assay, CLSM and SEM showed that VirR is not required for biofilm formation in L. monocytogenes EGD-e. A central finding of this study is that both VirAB and VirS are essential for biofilm formation and they could function as a whole in biofilm formation of L. monocytogenes EGD-e. The results also demonstrated that both VirAB and VirS are involved in attachment, but they are not associated with swarming motility. Results from RT-qPCR showed that flaA, motA and motB were downregulated in the mutant strains ΔvirAB and ΔvirS, which could be the possible reason for reduced attachment and biofilm formation in these mutants. This study provides a better understanding of the mechanisms involved in biofilm formation of L. monocytogenes, leading to improved processes to control this biofilm-forming foodborne pathogen.

RevDate: 2021-06-10

Harb M, Zarei-Baygi A, Wang P, et al (2021)

Antibiotic transformation in an anaerobic membrane bioreactor linked to membrane biofilm microbial activity.

Environmental research pii:S0013-9351(21)00750-7 [Epub ahead of print].

Although extensive research to date has focused on enhancing removal rates of antibiotics from municipal wastewaters, the transformation products formed by anaerobic treatment processes remain understudied. The present work aims to examine the possible roles that the different microbial communities of an anaerobic membrane bioreactor (AnMBR) play in the transformation of antibiotics during wastewater treatment. As part of this work, sulfamethoxazole, erythromycin, and ampicillin were added in separate stages to the influent of the AnMBR at incremental concentrations of 10, 50, and 250 μg/L each. Antibiotic-specific transformation products detected during each stage, as identified by high resolution LC-MS, are reported herein. Results suggest that both isoxazole (sulfamethoxazole) and β-lactam (ampicillin) ring opening could be facilitated by the AnMBR's bioprocess. Microbial community analysis results indicated that relative activity of the system's suspended biomass consistently shifted towards syntrophic groups throughout the duration of the experiment. Notable differences were also observed between the suspended biomass and the AnMBR's membrane biofilms. Membrane-attached biofilm communities showed high relative activities of several specific methanogenic (Methanothrix and Methanomethylovorans), syntrophic (Syntrophaceae), and sulfate-reducing (Desulfomonile) groups. Such groups have been previously identified as involved in the formation of the antibiotic degradation products observed in the effluent of the AnMBR. The activity of these communities within the biofilms likely confers certain advantages that aid in the biotransformation of the antibiotics tested.

RevDate: 2021-06-10

Oliveira DC, Thomson JJ, Alhabeil JA, et al (2021)

In vitro Streptococcus mutans adhesion and biofilm formation on different esthetic orthodontic archwires.

The Angle orthodontist pii:466174 [Epub ahead of print].

OBJECTIVES: To evaluate the ability of different esthetic archwires to retain oral biofilms in vitro.

MATERIALS AND METHODS: Seven different brands of coated orthodontic archwires were tested: two epoxy coated, two polytetrafluoroethylene coated, two rhodium coated, and one silver plus polymer coated. Conventional uncoated metallic archwires were used as controls. Streptococus mutans adherence to archwires was quantified by colony count following 24 hours of biolfilm growth, and total wire-associated biofilm was measured using a crystal violet staining assay. For both tests, two conditions were used: 0% sucrose and 3% sucrose. For statistical analysis, P < .05 was considered as statistically significant.

RESULTS: For S. mutans colony forming units per biofilm, there were no statistically significant differences among the various archwires (P = .795 for 0% sucrose; P = .905 for 3% sucrose). Regarding total biofilm formed on archwires in the 3% sucrose condition, there were statistically significant differences in crystal violet staining only for the comparison between Niti Micro Dental White and Copper Ni-Ti wires (P < .05).

CONCLUSIONS: The clinical use of esthetic-coated orthodontic wires may be considered to have similar risks as uncoated archwires for biofilm retention.

RevDate: 2021-06-10

Khaleghi M, S Khorrami (2021)

Down-regulation of biofilm-associated genes in mecA-positive methicillin-resistant S. aureus treated with M. communis extract and its antibacterial activity.

AMB Express, 11(1):85.

Considering the prevalence of resistance to antibiotics, the discovery of effective agents against resistant pathogens is of extreme urgency. Herein, 26 mecA-positive methicillin-resistant S. aureus (MRSA) isolated from clinical samples were identified, and their resistance to 11 antibiotics was investigated. Next, the antibacterial and anti-biofilm activity of the ethanolic extract of M. communis on these strains was evaluated. Furthermore, the effect of this extract on the expression of biofilm-associated genes, icaA, icaD, bap, sarA, and agr, was studied. According to the results, all isolated strains were multidrug-resistant and showed resistance to oxacillin and tetracycline. Also, 96.15 and 88.46 % of them were resistant to gentamicin and erythromycin. However, the extract could effectively combat the strains. The minimum inhibitory concentration (MIC) against different strains ranged from 1.56 to 25 mg/ml and the minimum bactericidal concentration (MBC) was between 3.125 and 50 mg/ml. Even though most MRSA (67 %) strongly produced biofilm, the sub-MIC concentration of the extract destroyed the pre-formed biofilm and affected the bacterial cells inside the biofilm. It could also inhibit biofilm development by significantly decreasing the expression of icaA, icaD, sarA and bap genes involved in biofilm formation and development. In conclusion, the extract inhibits biofilm formation, ruins pre-formed biofilm, and kills cells living inside the biofilm. Furthermore, it down-regulates the expression of necessary genes and nips the biofilm formation in the bud.

RevDate: 2021-06-10

Nag M, Lahiri D, Sarkar T, et al (2021)

Microbial Fabrication of Nanomaterial and Its Role in Disintegration of Exopolymeric Matrices of Biofilm.

Frontiers in chemistry, 9:690590 pii:690590.

Bacterial biofilms are responsible for the development of various chronic wound-related and implant-mediated infections and confer protection to the pathogenic bacteria against antimicrobial drugs and host immune responses. Hence, biofilm-mediated chronic infections have created a tremendous burden upon healthcare systems worldwide. The development of biofilms upon the surface of medical implants has resulted in the failure of various implant-based surgeries and therapies. Although different conventional chemical and physical agents are used as antimicrobials, they fail to kill the sessile forms of bacterial pathogens due to the resistance exerted by the exopolysaccharide (EPS) matrices of the biofilm. One of the major techniques used in addressing such a problem is to directly check the biofilm formation by the use of novel antibiofilm materials, local drug delivery, and device-associated surface modifications, but the success of these techniques is still limited. The immense expansion in the field of nanoscience and nanotechnology has resulted in the development of novel nanomaterials as biocidal agents that can be either easily integrated within biomaterials to prevent the colonization of microbial cells or directly approach the pathogen overcoming the biofilm matrix. The antibiofilm efficacies of these nanomaterials are accomplished by the generation of oxidative stresses and through alterations of the genetic expressions. Microorganism-assisted synthesis of nanomaterials paved the path to success in such therapeutic approaches and is found to be more acceptable for its "greener" approach. Metallic nanoparticles functionalized with microbial enzymes, silver-platinum nanohybrids (AgPtNHs), bacterial nanowires, superparamagnetic iron oxide (Fe3O4), and nanoparticles synthesized by both magnetotactic and non-magnetotactic bacteria showed are some of the examples of such agents used to attack the EPS.

RevDate: 2021-06-10

Judan Cruz KG, Alfonso ED, Fernando SID, et al (2021)

Candida albicans Biofilm Inhibition by Ethnobotanicals and Ethnobotanically-Synthesized Gold Nanoparticles.

Frontiers in microbiology, 12:665113.

The virulence and drug resistance of globally prevalent Candida albicans has presented complications toward its control while advances in effective antivirulence drugs remain critical. Emerging methods are now being evaluated to facilitate development of novel therapeutic approaches against this pathogen. This study focuses on the biofilm formation inhibition of ethnobotanical crude extracts and the use of nanotechnology through the ethnobotanically-synthesized gold nanoparticles to control C. albicans. Control on biofilm formation was compared using crude extracts (CEs) and biologically synthesized gold nanoparticles (CEs + AuNPs). Significantly lower biofilm formation was exhibited in thirteen (13) CEs and fourteen (14) CEs + AuNPs. Biofilm-linked genes Bcr1 and HSP90 expression were consequently downregulated. Higher biofilm inhibition activity was noted in some CEs + AuNPs compared to its counterpart CEs. This study emphasizes the biofilm inhibition activity of ethnobotanicals and the use of nanoparticles to enhance delivery of compounds, and points to its prospects for developing anti-pathogenic drugs without evolving resistance.

RevDate: 2021-06-09

Janež N, Škrlj B, Sterniša M, et al (2021)

The role of the Listeria monocytogenes surfactome in biofilm formation.

Microbial biotechnology [Epub ahead of print].

Listeria monocytogenes is a highly pathogenic foodborne bacterium that is ubiquitous in the natural environment and capable of forming persistent biofilms in food processing environments. This species has a rich repertoire of surface structures that enable it to survive, adapt and persist in various environments and promote biofilm formation. We review current understanding and advances on how L. monocytogenes organizes its surface for biofilm formation on surfaces associated with food processing settings, because they may be an important target for development of novel antibiofilm compounds. A synthesis of the current knowledge on the role of Listeria surfactome, comprising peptidoglycan, teichoic acids and cell wall proteins, during biofilm formation on abiotic surfaces is provided. We consider indications gained from genome-wide studies and discuss surfactome structures with established mechanistic aspects in biofilm formation. Additionally, we look at the analogies to the species L. innocua, which is closely related to L. monocytogenes and often used as its model (surrogate) organism.

RevDate: 2021-06-09

Chen X, Lorenzen J, Xu Y, et al (2021)

A novel chronic wound biofilm model sustaining coexistence of Pseudomonas aeruginosa and Staphylococcus aureus suitable for testing of antibiofilm effect of antimicrobial solutions and wound dressings.

Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society [Epub ahead of print].

Chronic wounds are a large burden to patients and healthcare systems. Biofilm infections in chronic wounds are crucial factors leading to non-healing of wounds. It is important to study biofilm in wounds and to develop effective interventions against wound biofilm. This study presents a novel in vitro biofilm model mimicking infected chronic wounds. The novel layered chronic wound biofilm model uses woundlike media and includes both Pseudomonas aeruginosa and Staphylococcus aureus, which have been identified as the most important pathogens in wounds. The model sustains their coexistence for at least 96 h. Microscopy of the model revealed microbial growth in non-surface attached microcolonies as previously observed in vivo. The model was used to determine log10 -reduction for the use of an antimicrobial solution and antimicrobial dressings (containing silver or honey) showing moderate-to-low antibiofilm effect, which indicates better concordance with the observed clinical performance of this type of treatment than other widely used standard tests.

RevDate: 2021-06-09

Kurt A, Özyurt E, N Topcuoğlu (2021)

Effect of different beverages on surface properties and cariogenic biofilm formation of composite resin materials.

Microscopy research and technique [Epub ahead of print].

The consumption of certain beverages may affect the physical and biological properties of resin composites (RCs) according to type. This in vitro study aimed to evaluate the surface properties and cariogenic biofilm formation in microhybrid and nanohybrid RCs after immersion in different beverages. The effects of four beverages (distilled water-control, tea, coffee, and cola) on two RCs (microhybrid and nanohybrid) were evaluated. Changes in the surface properties were evaluated for each group using surface roughness measurement (n = 10), scanning electron microscopy (SEM) (n = 4) observation, and energy-dispersive X-ray spectroscopy (EDX) (n = 5) analysis. In vitro Streptococcus mutans biofilm formation on the specimens of each group was determined using confocal laser scanning microscopy and SEM analysis (n = 14). The data were analyzed using two-way analysis of variance, with Bonferroni as a post-hoc test and Pearson's correlation (p < .05). Microhybrid RC presented more surface roughness (p = .014) and cariogenic biofilm formation (p = .040). The surface roughness (F = 0.733, p = .536) and cariogenic biofilm formation (F = 1.685, p = .181) values were not affected by the beverages. However, according to qualitative SEM and EDX measurements, these parameters varied depending on the beverage groups. No correlation was found between surface roughness and cariogenic biofilm formation (r = 0.135, p = .287). Microhybrid RCs had a rougher surface and a higher amount of cariogenic biofilm formation than nanohybrid RCs after being subjected to different beverages.

RevDate: 2021-06-09

Hazhirkamal M, Zarei O, Movahedi M, et al (2021)

Molecular typing, biofilm production, and detection of carbapenemase genes in multidrug-resistant Acinetobacter baumannii isolated from different infection sites using ERIC-PCR in Hamadan, west of Iran.

BMC pharmacology & toxicology, 22(1):32.

BACKGROUND: Acinetobacter baumannii is an opportunistic pathogen that can cause several kinds of nosocomial infections. Increasing antibiotic resistance as well as identifying genetic diversity and factors associated with pathogenicity and prevalence of this bacterium is important. The aim of this study was the investigation of molecular typing, biofilm production, and detection of carbapenemase genes in multidrug-resistant Acinetobacter baumannii isolated from different infection sites using ERIC-PCR in Iran.

METHODS: Forty isolates of A. baumannii were obtained from various wards of the central hospital, in the west of Iran. Phenotypic identification and genetic diversity, biofilm production assay, and detection of Carbapenemase genes carried out.

RESULTS: Tracheal samples 26 (61.9 %) are the most frequent isolates, and 95 % of isolates were identified as MDR. 32.5 % of all A. baumannii strains were capable to form a strong biofilm. It was founded that antimicrobial resistance patterns had a significant relationship with strong biofilm formation (P = 0.001). Most frequencies of the studied genes were in the order of VIM (81 %), SPM (45.2 %), and IMP (35.7 %) genes. The VIM gene was the most frequent in all isolates which were significant (P = 0.006). 14 different ERIC-types were observed including 7 common types and 7 unique or single types. F type is the largest common type consisting of nine isolates and B, D, and E types contain two isolates separately.

CONCLUSIONS: ERIC-PCR technique was used to genetically classify A. baumannii isolates as one of the most common microorganisms in nosocomial infections.

RevDate: 2021-06-09

Huang Q, Zhang Z, Liu Q, et al (2021)

SpoVG is an important regulator of sporulation and affects biofilm formation by regulating Spo0A transcription in Bacillus cereus 0-9.

BMC microbiology, 21(1):172.

BACKGROUND: Bacillus cereus 0-9, a Gram-positive, endospore-forming bacterium isolated from healthy wheat roots in our previous research, is considered to be an effective biocontrol strain against several soil-borne plant diseases. SpoVG, a regulator that is broadly conserved among many Gram-positive bacteria, may help this organism coordinate environmental growth and virulence to survive. This study aimed to explore the multiple functions of SpoVG in B. cereus 0-9.

METHODS: The gene knockout strains were constructed by homologous recombination, and the sporulation process of B. cereus 0-9 and its mutants were observed by fluorescence staining method. We further determined the spore yields and biofilm formation abilities of test strains. Transcriptional fusion strains were constructed by overlapping PCR technique, and the promoter activity of the target gene was detected by measuring its fluorescence intensity. The biofilm production and colonial morphology of B. cereus 0-9 and its mutants were determined to study the functions of the target genes, and the transcription level of the target gene was determined by qRT-PCR.

RESULTS: According to observation of the sporulation process of B. cereus 0-9 in germination medium, SpoVG is crucial for regulating sporulation stage V of B. cereus 0-9, which is identical to that of Bacillus subtilis but differs from that of Bacillus anthracis. In addition, SpoVG could influence biofilm formation of B. cereus 0-9. The transcription levels of two genes closely related to biofilm-formation, sipW and calY, were downregulated in a ΔspoVG mutant. The role of SpoVG in regulating biofilm formation was further explored by deleting the genes abrB and sinR in the ΔspoVG mutant, respectively, generating the double mutant strains ΔspoVGΔabrB and ΔspoVGΔsinR. The phenotypes of these double mutants were congruent with those of the single abrB and sinR deletion strains, respectively, which showed increased biofilm formation. This indicated that spoVG was located upstream of abrB and sinR in the regulatory pathway of B. cereus biofilm formation. Further, the results of qRT-PCR and the luminescence intensity of transcriptional fusion strains indicated that spoVG gene deletion could inhibit the transcription of Spo0A.

CONCLUSIONS: SpoVG, an important regulator in the sporulation of B. cereus, is located upstream of Spo0A and participates in regulation of biofilm formation of B. cereus 0-9 through regulating the transcription level of spo0A. Sporulation and biofilm formation are crucial mechanisms by which bacteria respond to adverse conditions. SpoVG is therefore an important regulator of Spo0A and is crucial for both sporulation and biofilm formation of B. cereus 0-9. This study provides a new insight into the regulatory mechanism of environmental adaptation in bacteria and a foundation for future studies on biofilm formation of B. cereus.

RevDate: 2021-06-08

Paosen S, Lethongkam S, Wunnoo S, et al (2021)

Prevention of nosocomial transmission and biofilm formation on novel biocompatible antimicrobial gloves impregnated with biosynthesized silver nanoparticles synthesized using Eucalyptus citriodora leaf extract.

Biotechnology journal [Epub ahead of print].

BACKGROUND: Failure in the prevention of cross-transmission from contaminated gloves has been recognized as an important factor that contributes to the spread of several healthcare-associated infections.

METHODS AND RESULTS: Ex situ coating process with silver nanoparticles (AgNPs) using Eucalyptus citriodora ethanolic leaf extract as reducing and capping agents to coat glove surfaces has been developed to prevent this mode of transmission. Elemental analysis of coated gloves showed 24.8 Wt% silver densely adhere on the surface. The coated gloves fully eradicated important hospital-acquired pathogens including Gram-positive bacteria, Gram-negative bacteria, and yeasts within 1 h. The coated gloves showed significant reduction, an average of 5 logs when tested against all standard strains and most clinical isolates (p < 0.01). Following prolonged exposure, the coating significantly reduced the numbers of most adhered pathogenic species, compared with uncoated gloves (p < 0.0001). AgNPs-coated gloves reduced microbial adhesion of mixed-species biofilms. A series of contamination and transmission assays demonstrated no transmission of viable organisms. Biocompatibility analysis confirmed high viability of HaCaT and L929 cells at all concentrations of AgNPs tested. The coated gloves were non-toxic with direct contact with L929 cells.

CONCLUSION: The highly efficacious AgNPs-coated gloves potentially provide additional protection against transmission of healthcare-associated infections. This article is protected by copyright. All rights reserved.

RevDate: 2021-06-08

Wang X, Wang Y, Ling N, et al (2021)

Roles of tolC on tolerance to bile salts and biofilm formation in Cronobacter malonaticus.

Journal of dairy science pii:S0022-0302(21)00647-0 [Epub ahead of print].

Bile salts is one of essential components of bile secreted into the intestine to confer antibacterial protection. Cronobacter species are associated with necrotizing enterocolitis in newborns and show a strong tolerance to bile salts. However, little attempt has been made to focus on the molecular basis of the tolerance to bile salts. In this study, we investigated the roles of tolC on growth, cell morphology, motility, and biofilm formation ability in Cronobacter malonaticus under bile salt stress. The results indicated that the absence of tolC significantly affected the colony morphology and outer membrane structure in a normal situation, compared with those of the wild type strain. The deletion of tolC caused the decline in resistance to bile salt stress, inhibition of growth, and observable reduction in relative growth rate and motility. Moreover, the bacterial stress response promoted the biofilm formation ability of the mutant strain. The expression of the AcrAB-TolC system (acrA, acrB, and tolC) was effectively upregulated compared with the control sample when exposed to different bile salt concentrations. The findings provide valuable information for deeply understanding molecular mechanisms about the roles of tolC under bile salt stress and the prevention and control of C. malonaticus.

RevDate: 2021-06-07

Dzofou Ngoumelah D, Harnisch F, J Kretzschmar (2021)

Benefits of Age-Improved Resistance of Mature Electroactive Biofilm Anodes in Anaerobic Digestion.

Environmental science & technology [Epub ahead of print].

Anaerobic digestion (AD) and microbial electrochemical technologies (MET) can be combined in manifold ways. Recent studies show negative influences of AD effluents on the performance of pre-grown Geobacter spp.-dominated biofilm anodes. In this study, it was investigated how such biofilm anodes are affected by AD effluents. Therefore, experiments using AD effluents in different concentrations (0-100%) in combination with biofilms of different ages were performed. Furthermore, the activity of methanogens was inhibited and minimized by application of 2-bromoethanesulfonate (2-BES) and microfiltration, respectively. Biofilms pre-grown for 5 weeks show higher resistance against AD effluents compared to biofilms pre-grown for only 3 weeks. Nevertheless, adaptation of biofilms to AD effluents was not successful. Biofilm activity in terms of coulombic efficiency and maximum current density (jmax) dropped by factor 32.2 ± 3.2 and 38.9 ± 8.4, respectively. The application of 2-BES and microfiltration had positive effects on the biofilm activity. The results support the assumption that methanogens or further compounds not studied here, for example, protozoans, which may have been inhibited or removed by 2-BES application or microfiltration, have an immediate influence on the stability of Geobacter spp.-dominated biofilms and may limit their practical application in AD environments.

RevDate: 2021-06-07

Mahajan S, Sunsunwal S, Gautam V, et al (2021)

Biofilm inhibitory effect of alginate lyases on mucoid P. aeruginosa from a cystic fibrosis patient.

Biochemistry and biophysics reports, 26:101028 pii:S2405-5808(21)00122-9.

Chronic mucoid Pseudomonas aeruginosa infections are a major scourge in cystic fibrosis patients. Mucoid P. aeruginosa displays structured alginate-rich biofilms that are resistant to antibiotics. Here, we have assessed the efficacy of a panel of alginate lyases in combating mucoid P. aeruginosa biofilms in cystic fibrosis. Albeit we could not demonstrate alginate degradation by alginate lyases in sputum, we demonstrate that the endotypic alginate lyases, CaAly (from Cellulophaga algicola) and VspAlyVI (from Vibrio sp. QY101) and the exotypic alginate lyases, FspAlyFRB (from Falsirhodobacterium sp. alg1), and SA1-IV (from Sphingomonas sp. A1), indeed inhibit biofilm formation by a mucoid P. aeruginosa strain isolated from the sputum of a cystic fibrosis patient with comparative effect to that of the glycoside hydrolase PslG, a promising candidate for biofilm treatment. We believe that these enzymes should be explored for in vivo efficacy in future studies.

RevDate: 2021-06-07

Zahedani SS, Tahmasebi H, M Jahantigh (2021)

Coexistence of Virulence Factors and Efflux Pump Genes in Clinical Isolates of Pseudomonas aeruginosa: Analysis of Biofilm-Forming Strains from Iran.

International journal of microbiology, 2021:5557361.

Background: Biofilm formation and efflux pumps (EPs) correlation play a critical role in the pathogenicity and antibiotic resistance of Pseudomonas aeruginosa. In this study, biofilm formation and EP's collaborative role in clinical isolates of P. aeruginosa infection were investigated.

Methods: Eighty-six (86) P. aeruginosa isolates were collected from different clinical specimens and were confirmed using different biochemical tests. The formation of biofilm was investigated by using a crystal violet assay. Also, EP genes were identified by the PCR method.

Results: Based on the results, gentamicin-resistant (n = 50, 66.29%) and ciprofloxacin-resistant (n = 61, 69.66%) strains were the most frequent and colistin (n = 1, 1.12%) and ceftazidime (n = 12, 7.86%) resistant strains were the least prevalent. Furthermore, 22 isolates (31.42%) were MDR, and 11 isolates (12.35%) were XDR strains. Also, 19 isolates (22.47%) were classified as strong biofilm, 29 isolates (21.34%) as moderate biofilm, and 3 (11.23%) isolates as weak biofilm producers. The distribution of the EP genes was as follows: mexA (n = 44, 34.83%), mexB (n = 33, 32.58%), oprM (n = 59, 29.21%), oprD (n = 61, 30.33%), tetA (n = 22, 25.58%), tetR (n = 19, 22.09%), and emrE (n = 21, 24.41%). However, there was a strong significant association between biofilm formation and EPs in P. aeruginosa. Conclusions. In this study, we suggested that the presence of a multidrug resistance efflux pump, MexEF-OprN, significantly reduced P. aeruginosa pathogenicity. In contrast, the presence of the MexAB-OprM and MexCD-OprJ pumps did not affect virulence.

RevDate: 2021-06-07

Ohn HM, Mizuno T, SI Miyoshi (2021)

Inhibitory Effects of Escherichia coli on the Formation and Development of Staphylococcus epidermidis Biofilm.

Biocontrol science, 26(2):113-118.

In the present study, we examined whether a commensal gut bacterium Escherichia coli might prevent the formation and development of the biofilm of Staphylococcus epidermidis, a nosocomial extraintestinal pathogen but not a gut microorganism. When co-cultured with S. epidermidis, E. coli strain ATCC 35218, a non-pathogenic strain, was found to be dominant in the biofilm formed on the surface of wells of a microtiter plate. In addition, E. coli significantly incorporated and grew in a niche preoccupied by S. epidermidis biofilm. Two other E. coli strains (strain K-12 and B) also showed to interfere the biofilm formation by S. epidermidis. In contrast, S. epidermidis could not grow in a niche preoccupied by E. coli biofilm. These results suggest that, through inhibition of the formation and development of the biofilm, E. coli may eliminate S. epidermidis from the gastrointestinal tract.

RevDate: 2021-06-06

Zhang C, Li Q, Zhan L, et al (2021)

Responses of submerged macrophytes Vallisneria natans and epiphytic biofilm to floating plants Eichhornia crassipes in eutrophic water.

Water environment research : a research publication of the Water Environment Federation [Epub ahead of print].

The degeneration of submerged macrophytes and the invasion of Eichhornia crassipes (E. crassipes) destroyed the balance of aquatic ecosystems environments. In this study, responses of Vallisneria natans (V. natans) and the leaf-epiphytic biofilms to E. crassipes were analyzed to provide a technical scheme for V. natans restoration and E. crassipes control in eutrophic water. The results showed that a significant improvement of water quality achieved in 1100 ind·m-2 E. crassipes density group and TN removal rate reached 63.53%. The presence of E. crassipes changed the morphological characteristics of V. natans, which stimulated the adaptive mechanisms via promotion of shoot height and root length. Concentrations of the antioxidant enzymes, peroxidase, superoxide dismutase, and catalase in the V. natans leaves remained stable. But E. crassipes greatly increased the microbial diversity on V. natans leave biofilms. Furthermore, the greatest richness in bacterial community diversity was observed at 700, 1100 and 1200 ind·m-2 E. crassipes densities in heatmap, which was beneficial to the stability of the water ecological environment. These results showed that the combination of V. natans with E. crassipes of 1100 ind·m-2 providing more favorable conditions for the growth and restoration of submerged macrophytes and improve the water quality.

RevDate: 2021-06-06

Qiao Y, Feng L, Jia R, et al (2021)

Motility, biofilm formation and associated gene expression in Vibrio parahaemolyticus impaired by co-culture with live Ulva fasciata.

Journal of applied microbiology [Epub ahead of print].

AIMS: Vibrio (V.) parahaemolyticus is one of the most frequently occurred pathogens in mariculture. This study aimed to explore the mechanism of the impact of Ulva fasciata (U. fasciata) on the motility and biofilm formation of V. parahaemolyticus.

METHODS AND RESULTS: The inhibitory effect of U. fasciata on a V. parahaemolyticus, isolated from clam maricultural sediment, was examined by co-culture. The live U. fasciata significantly inhibited the swimming behaviour, twitching behaviour and biofilm formation of V. parahaemolyticus JF, with inhibition rates ranging from 2.48%-20.26%, 1.59-39.18%, and 28.3-94.7% under different nitrate and phosphate levels. The results of transcriptome sequencing showed that 210 significantly differentially expressed genes were found in strain JF between the presence and absence of U. fasciata, including 90 upregulated genes and 120 downregulated genes. According to GO (Gene Ontology) function enrichment and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis, the downregulated genes of JF were partially enriched in flagella assembly (fliC, fliK, fliG, fliN, fliH, fliI, fliJ, fliA), bacterial chemotaxis (mCP, cheB, cheW, cheY) and biofilm formation (fliA/σ28 , eps), which explained the suppressed motility and biofilm formation of V. parahaemolyticus JF under U. fasciata stress.

CONCLUSIONS: Live U. fasciata significantly impaired the motility and biofilm formation of V. parahaemolyticus, which could occur in niches with either sufficient or inadequate nutrient (nitrate and phosphate) concentrations. The differentially expressed genes of V. parahaemolyticus modulated by U. fasciata were enriched mainly in the flagellar assembly, bacterial chemotaxis and biofilm pathways.

New information on how V. parahaemolyticus respond to U. fasciata regarding motility and adhesion behaviours, and the mechanism of that was firstly explored in this study. The results suggested that the seaweed U. fasciata has promising prospects as an environmentally friendly preventive measure to treat vibriosis in mariculture.

RevDate: 2021-06-06

Liu J, Zhang D, Lian S, et al (2021)

Mechanism of nitrite transporter NirC in motility, biofilm formation, and adhesion of avian pathogenic Escherichia coli.

Archives of microbiology [Epub ahead of print].

The Escherichia coli (E. coli) nirC gene encodes a nitrite transporter, which involved in transporting toxic nitrite (NO2-) from the environment into the bacteria. Although the deletion of nirC gene could cause changes in motility, adhesion in the previous study, and the virulence involved in the specified mechanism for pathogenic E. coli remains to be known. In the present work, we aimed to evaluate the role of NirC in a serotype O2:K1:H7 avian pathogenic Escherichia coli (APEC) strain. For this purpose, we generated a NirC-deficient mutant of APEC XM strain and examined its biological characteristics. The nirC gene deletion mutant enhanced ability of motility, decreased in biofilm formation, and it markedly reduced ability to adhere mouse brain microvascular endothelial cell b.End3 cells. For understanding its mechanism, sequentially we detected and found the stress regulator rpoS and its downstream genes csrA were up-regulated in NirC-deficient mutant while diguanylate cyclase gene dgcT was down-regulated. By high-performance liquid chromatography (HPLC) experiment, we demonstrated the concentration of intracellular 3',5'-cyclic diguanosine monophosphate (c-di-GMP) significantly decrease in nirC gene deletion mutant. Taken data together, we may make a conclusion with a possible signal pathway clue, due to NirC mutation, environmental NO2- accumulation leads to nitrite stress and inactivates c-di-GMP synthesis by stimulating the stress regulator RpoS, resulting in changes of biological characteristics.

RevDate: 2021-06-05

Liu M, Zhu X, Zhang C, et al (2021)

LuxQ-LuxU-LuxO pathway regulates biofilm formation by Vibrio parahaemolyticus.

Microbiological research, 250:126791 pii:S0944-5013(21)00097-5 [Epub ahead of print].

Vibrio parahaemolyticus, a common foodborne pathogen, can form biofilms for survival in various environments and for bacterial transmission. Lux systems in Vibrio species are the typical two-component signal transduction systems, which have been demonstrated to contribute to various phenotypes; however, the functions of each homolog of the Lux system in V. parahaemolyticus in the regulation of biofilm formation remain largely unknown. In this study, we first showed that LuxQ, LuxU, and LuxO are essential for controlling biofilm formation by V. parahaemolyticus, through gene knockout studies. We also found that they acted in the same signaling pathway and their deletion mutants exhibited a similar level of biofilm formation. Furthermore, site-directed mutagenesis revealed that the conserved residues for phosphorylation in LuxQ (D784), LuxU (H56) and LuxO (D47) were critical for their regulatory functions on biofilm formation. Phos-tag™ sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed the phosphorylation of LuxU and LuxQ in vivo. Finally, qPCR analysis displayed that the three mutants had a significant decrease in the transcription level of cps loci and cpsQ compared with the wild type strain, which is consistent with the observed phenotype of biofilm formation. Therefore, we propose that LuxQ and its downstream factors LuxU and LuxO function in the same signaling cascade to control biofilm formation by regulating the expression of cpsQ and cps loci. The results of this study provide new data regarding the role of the LuxQ-LuxU-LuxO pathway in biofilm formation by V. parahaemolyticus and help further understand the complex regulatory functions of Lux pathways.

RevDate: 2021-06-05

Roy PK, Ha AJ, Mizan MFR, et al (2021)

Effects of environmental conditions (temperature, pH, and glucose) on biofilm formation of Salmonella enterica serotype Kentucky and virulence gene expression.

Poultry science, 100(7):101209 pii:S0032-5791(21)00243-1 [Epub ahead of print].

Salmonella is a foodborne pathogen and an emerging zoonotic bacterial threat in the food industry. The aim of this study was to evaluate the biofilm formation by a cocktail culture of 3 wild isolates of Salmonella enterica serotype Kentucky on plastic (PLA), silicon rubber (SR), and chicken skin surfaces under various temperatures (4, 10, 25, 37, and 42°C) and pH values (4.0, 5.0, 6.0, 7.0, and 8.0). Then, at the optimum temperature and pH, the effects of supplementation with glucose (0, 0.025, 0.05, and 0.4% w/v) on biofilm formation were assessed on each of the surfaces. The results indicated that higher temperatures (25 to 42°C) and pH values (7.0 and 8.0) led to more robust biofilm formation than lower temperatures (4 and 10°C) and lower pH levels (4.0 to 6.0). Moreover, biofilm formation was induced by 0.025% glucose during incubation at the optimum temperature (37°C) and pH (7.0) but inhibited by 0.4% glucose. Consistent with this finding, virulence related gene (rpoS, rpoH, hilA, and avrA) expression was increased at 0.025% glucose and significantly reduced at 0.4% glucose. This results also confirmed by field emission scanning electron microscope, confocal laser scanning microscopy, and autoinducer-2 determination. This study concluded that optimum environmental conditions (temperature 37°C, pH 7.0, and 0.25% glucose) exhibited strong biofilm formation on food and food contract surfaces as well as increased the virulence gene expression levels, indicating that these environmental conditions might be threating conditions for food safety.

RevDate: 2021-06-05

Farrokhi Y, Al-Shibli B, Falah-Joudah Al-Hameedawi D, et al (2021)

Escherichia coli enhances the virulence factors of Candida albicans, the cause of vulvovaginal candidiasis, in a dual bacterial/fungal biofilm.

Research in microbiology pii:S0923-2508(21)00063-2 [Epub ahead of print].

Co-infection with other microorganisms can promote the Candida albicans to be invasive. In this study, Escherichia coli and C. albicans were co-isolated from the women with candidiasis symptoms. The in vitro effects of E. coli on C. albicans hypha development, biofilm formation, antibiotic susceptibility, dispersion from the biofilm, expression of Als3, Hwp1, and Tup1 genes, and pathogenesis in Galleria mellonella were investigated. Electron microscopic images revealed that hypha induction was markedly increased in the bacteria-fungi co-culture. Biofilm formation was increased 2.2 fold in the presence of E. coli. The minimum inhibitory concentration of nystatin against Candida was increased from (μg mL-1) 25 to 50 in the dual biofilm. Candida dissemination was increased up to 2.7 fold from the mixed fungi/bacteria biofilm. The expression of ALS3 and HWP1 genes was increased (5.9 and 2.0 fold, respectively) while the TUP1 gene expression was decreased (0.4 fold) when C. albicans was incubated with E. coli. The simultaneous injection of C. albicans and E. coli to the insect larvae increased Galleria mortality up to 40%. This study demonstrated the effects of E. coli to promote fungi virulence factors, which suggest polymicrobial interaction should be considered during treatment of fungal infections.

RevDate: 2021-06-05

Ding L, Wang J, Cai S, et al (2021)

Pulmonary Biofilm-Based Chronic Infections and Inhaled Treatment Strategies.

International journal of pharmaceutics pii:S0378-5173(21)00573-1 [Epub ahead of print].

Certain pulmonary diseases, such as cystic fibrosis (CF), non-CF bronchiectasis, chronic obstructive pulmonary disease, and ventilator-associated pneumonia, are usually accompanied by respiratory tract infections due to the physiological alteration of the lung immunological defenses. Recurrent infections may lead to chronic infection through the formation of biofilms. Chronic biofilm-based infections are challenging to treat using antimicrobial agents. Therefore, effective ways to eradicate biofilms and thus relieve respiratory tract infection require the development of efficacious agents for biofilm destruction, the design of delivery carriers with biofilm-targeting and/or penetrating abilities for these agents, and the direct delivery of them into the lung. This review provides an in-depth description of biofilm-based infections caused by pulmonary diseases and focuses on current existing agents that are administered by inhalation into the lung to treat biofilm, which include i) inhalable antimicrobial agents and their combinations, ii) non-antimicrobial adjuvants such as matrix-targeting enzymes, mannitol, glutathione, cyclosporin A, and iii) liposomal formulations of anti-biofilm agents. Finally, novel agents that have shown promise against pulmonary biofilms as well as traditional and new devices for pulmonary delivery of anti-biofilm agents into the lung are also discussed.

RevDate: 2021-06-05

Niek WK, Teh CSJ, Idris N, et al (2021)

Investigation of biofilm formation in methicillin-resistant Staphylococcus aureus associated with bacteraemia in a tertiary hospital.

Folia microbiologica [Epub ahead of print].

Biofilm formation is an important physiological process in Staphylococcus aureus (S. aureus) that can cause infections in humans. In this study, the ability of 36 methicillin-resistant S. aureus (MRSA) clinical isolates to form biofilm was studied based on genotypic and phenotypic approaches. These isolates were genotyped based on the microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) and biofilm-associated genes (icaAD) via polymerase chain reactions. Phenotyping was performed based on the determination of the strength of biofilm formation of MRSA isolates in vitro. The most prevalent MSCRAMMs and biofilm-associated genes were clfA, eno, and icaD, followed by clfB. The fnbB (38.9%) and ebpS (11.1%) occurred less frequently among the MRSA isolates, while bbp and fnbA genes were absent from all isolates. The MRSA isolates were mostly moderate to strong biofilm formers, despite the heterogeneity of the MSCRAMM profiles. MRSA isolates from different infection sources (primary, catheter-related bloodstream, or secondary infections) were capable of forming strong biofilms. However, persistent bacteraemia was observed only in 19.4% of the MRSA-infected individuals. This study suggested that persistent MRSA bacteraemia in patients might not be associated with the biofilm-forming ability of the isolates.

RevDate: 2021-06-05

Hihara H, Tagaino R, Washio J, et al (2021)

Effectiveness and safety of a new dental plaque removal device utilizing micro mist spray for removing oral biofilm in vitro.

BMC oral health, 21(1):286.

BACKGROUND: Removal of oral biofilm from the oral mucosa is essential for preventing risk of respiratory and gastrointestinal infection in elderly people. Currently, no device is available which can remove oral biofilm from oral mucosa effectively and safely. Therefore, the effectiveness and safety of the Micro Scale Mist UNIT (MSM-UNIT), a newly developed dental plaque removal device utilizing high speed sprays of fine water droplets, were evaluated for biofilm removal, including the rate and surface roughness for simulated tooth surface and mucous membrane.

METHODS: Simulated tooth and oral mucosa coated with an artificial biofilm of Streptococcus mutans were used for evaluation of effectiveness, with uncoated substrates as the controls. The MSM-UNIT and a conventional air ablation device were operated under recommended instructions. The effectiveness was evaluated from the rate of removal of the biofilm, and the safety was evaluated from the damage observed by scanning electron microscope and surface roughness.

RESULTS: The biofilm removal rate of the MSM-UNIT was significantly higher than that of AIRFLOW. Little damage was observed in the area treated by the MSM-UNIT. The surface roughness of the MSM-UNIT treated area on simulated tooth surface and oral mucosa showed no significant difference to the control area. In contrast, cracks and powder were observed in the area treated by AIRFLOW. In particular, the surface roughness of the AIRFLOW treated area for Toughsilon was significantly larger than that of the control.

CONCLUSIONS: The MSM-UNIT could be used safely and effectively for removing biofilm not only on simulated tooth surfaces but also simulated mucous membrane. The MSM-UNIT has no harmful effect on teeth or oral mucosa, and may be used for comprehensive oral care for patients during nursing care and the perioperative period.

RevDate: 2021-06-05

Lu N, Li L, Wang C, et al (2021)

Simultaneous enhancement of power generation and chlorophenol degradation in nonmodified microbial fuel cells using an electroactive biofilm carbon felt anode.

The Science of the total environment, 783:147045.

Microbial fuel cells (MFCs) are an emerging technique presenting remarkable potential. In the current MFC, an electroactive biofilm anode was inoculated with activated sludge from a local municipal sewage treatment plant. The output voltage peaked at 0.60 V and 0.56 V in MFCs cultured with 2-chlorophenol (MFC-2-CP) and 2,4-dichlorophenol (MFC-2,4-DCP), respectively. The degradation and mineralization efficiency in MFC-2-CP were 100.0% and 82.0%, respectively. Based on the bacterial 16S rRNA gene sequence analysis, abundant Acinetobacter and Azospirillum existed during both the bioelectricity and biodegradation stages in MFC-2-CP, but different patterns were exhibited in MFC-2,4-DCP. The electrogenic bacteria relied on the electron transfer pathway of nicotinamide adenine dinucleotide dehydrogenase, succinate dehydrogenase and terminal oxidase, while the electrons were transferred to the extracellular electrode by cytochrome C, riboflavin, degradation products of CPs and flagella. 2-CP and 2,4-DCP were biodegraded into less toxic cyclohexanol via dichlorination, hydroxylation, and hydrogenation; hereafter, the ring was opened to generate long-chain hydrocarbons, and finally mineralized into CO2 and H2O. This work provided a new strategy for MFCs in power generation and contaminant treatment.

RevDate: 2021-06-05

Yang C, Liu T, Chen N, et al (2021)

Performance and mechanism of a novel woodchip embedded biofilm electrochemical reactor (WBER) for nitrate-contaminated wastewater treatment.

Chemosphere, 276:130250.

In this study, a woodchip biofilm electrode reactor (WBER) with woodchips embedded anode and cathode was developed, and its denitrification mechanism was analyzed by investigating the denitrification performance, organic matter change, redox environment and microbial community. The results show that the WBER with a carbon rod as anode (C-WBER) had a higher denitrification efficiency (2.58 mg NO- 3-N/(L·h)) and lower energy consumption (0.012 kWh/g NO- 3-N) at 350 mA/m2. By reducing the hydroxyl radical and dissolved oxygen concentrations, anode embedding technology effectively decreased the inhibition on microorganisms. Lignin decomposition, nitrification and aerobic denitrification were carried out in anode. Additionally, hydrogen autotrophic denitrification and heterotrophic denitrification were occurred in cathode. The WBER effectively removed nitrate and reduced the cost, providing a theoretical basis and direction for further develop BERs.

RevDate: 2021-06-04

Ozma MA, Khodadadi E, Rezaee MA, et al (2021)

Induction of proteome changes involved in biofilm formation of Enterococcus faecalis in response to gentamicin.

Microbial pathogenesis pii:S0882-4010(21)00275-8 [Epub ahead of print].

BACKGROUND: Enterococcus faecalis is a significant cause of nosocomial infections and other diseases, including endocarditis, bacteremia, and urinary tract infections. This microorganism forms biofilms to overcome difficult environmental conditions, such as lack of oxygen, lack of water, and the presence of antimicrobials. These biofilms make diseases difficult by changing their proteome contents, protecting the bacterium, and increasing their pathogenicity. This study aimed to evaluate gentamicin's effect on proteome changes and biofilm formation in E. faecalis.

METHOD: Twenty-five clinical isolates and one standard isolate were selected for the experiments. A label-free/gel-free proteomic and microtiter plate techniques were used to study proteome changes and biofilm formation, respectively.

RESULTS: Gentamicin significantly increased the biofilm formation in 62% of isolates and the rest of the isolates; no significant change was observed. The abundance of lactate utilization protein C, ribosomal RNA small subunit methyltransferase H, and protein translocase subunit SecA were increased. However, the abundances of proteins effective in cell division and metabolism, such as replication initiation protein and segregation and condensation protein A, were decreased.

CONCLUSION: The present study's findings exhibited that antibiotics might have adverse effects on treatment and increase microorganisms' pathogenicity. It was observed in gentamicin as induction of biofilm formation through different mechanisms, particularly changes in the expression of specific proteins in E. faecalis.

RevDate: 2021-06-04

Danforth DR, Melloni M, Tristano J, et al (2021)

Contribution of Adhesion Proteins to Aggregatibacter actinomycetemcomitans Biofilm Formation.

Molecular oral microbiology [Epub ahead of print].

Aggregatibacter actinomycetemcomitans is a Gram-negative bacterium associated with periodontal disease and multiple disseminated extra-oral infections. Colonization of these distinct physiological niches is contingent on the expression of specific surface proteins during the initiation of developing biofilms. In this investigation, we studied fimbriae and three well characterized non-fimbrial surface proteins (EmaA, Aae and ApiA/Omp100) for their contribution to biofilm formation. Mutations of these proteins in multiple strains covering four different serotypes demonstrated variance in biofilm development that was strain dependent but independent of serotype. In a fimbriated background, only inactivation of emaA impacted biofilm mass. In contrast, inactivation of emaA and/or aae affected biofilm formation in non-fimbriated A. actinomycetemcomitans strains, whereas inactivation of apiA/omp100 had little effect on biofilm formation. When these genes were expressed individually in Escherichia coli, all transformed strains demonstrated an increase in biofilm mass compared to the parent strain. The strain expressing emaA generated the greatest mass of biofilm, whereas the strains expressing either aae or apiA/omp100 were greatly reduced and similar in mass. These data suggest a redundancy in function of these non-fimbrial adhesins, which is dependent on the genetic background of the strain investigated. This article is protected by copyright. All rights reserved.

RevDate: 2021-06-04

Merkl P, Zhou S, Zaganiaris A, et al (2021)

Plasmonic Coupling in Silver Nanoparticle Aggregates and Their Polymer Composite Films for Near-Infrared Photothermal Biofilm Eradication.

ACS applied nano materials, 4(5):5330-5339.

Plasmonic nanoparticles with near-IR (NIR) light absorption are highly attractive in biomedicine for minimally invasive photothermal treatments. However, these optical properties are typically exhibited by plasmonic nanostructures with complex, nonspherical geometries that may prohibit their broad commercialization and further integration into photothermal devices. Herein, we present the single-step aerosol self-assembly of plasmonic nanoaggregates that consisted of spherical silver nanoparticles with tunable extinction from visible to NIR wavelengths. This tunable extinction was achieved by the addition of SiO2 during the flame synthesis of the nanoparticles, which acted as a dielectric spacer between the spherical silver nanoparticles and was also computationally validated by simulating the extinction spectra of similar silver nanoaggregates. These plasmonic nanoaggregates were easily deposited on silicone polymeric surfaces and further encased with a top polymer layer, forming plasmonic photothermal nanocomposite films. The photothermal properties of the NIR nanocomposite films were utilized to eradicate the established biofilms of clinically relevant Escherichia coli and Staphylococcus aureus, with a relationship observed between the final surface temperature and biofilm eradication.

RevDate: 2021-06-04

Brooks JR, Dusane DH, Moore K, et al (2021)

Pseudomonas aeruginosa biofilm killing beyond the spacer by antibiotic-loaded calcium sulfate beads: an in vitro study.

Journal of bone and joint infection, 6(5):119-129 pii:01021829.

Introduction: Bacterial biofilms are an important virulence factor in chronic periprosthetic joint infection (PJI) and other orthopedic infection since they are highly tolerant to antibiotics and host immunity. Antibiotics are mixed into carriers such as bone cement and calcium sulfate bone void fillers to achieve sustained high concentrations of antibiotics required to more effectively manage biofilm infections through local release. The effect of antibiotic diffusion from antibiotic-loaded calcium sulfate beads (ALCS-B) in combination with PMMA bone cement spacers on the spread and killing of Pseudomonas aeruginosa Xen41 (PA-Xen41) biofilm was investigated using a "large agar plate" model scaled for clinical relevance. Methods: Bioluminescent PA-Xen41 biofilms grown on discs of various orthopedic materials were placed within a large agar plate containing a PMMA full-size mock "spacer" unloaded or loaded with vancomycin and tobramycin, with or without ALCS-B. The amount of biofilm spread and log reduction on discs at varying distances from the spacer was assessed by bioluminescent imaging and viable cell counts. Results: For the unloaded spacer control, PA-Xen41 spread from the biofilm to cover the entire plate. The loaded spacer generated a 3 cm zone of inhibition and significantly reduced biofilm bacteria on the discs immediately adjacent to the spacer but low or zero reductions on those further away. The combination of ALCS-B and a loaded PMMA spacer greatly reduced bacterial spread and resulted in significantly greater biofilm reductions on discs at all distances from the spacer. Discussion: The addition of ALCS-B to an antibiotic-loaded spacer mimic increased the area of antibiotic coverage and efficacy against biofilm, suggesting that a combination of these depots may provide greater physical antibiotic coverage and more effective dead space management, particularly in zones where the spread of antibiotic is limited by diffusion (zones with little or no fluid motion).

RevDate: 2021-06-04

Edel M, Sturm G, Sturm-Richter K, et al (2021)

Extracellular riboflavin induces anaerobic biofilm formation in Shewanella oneidensis.

Biotechnology for biofuels, 14(1):130.

BACKGROUND: Some microorganisms can respire with extracellular electron acceptors using an extended electron transport chain to the cell surface. This process can be applied in bioelectrochemical systems in which the organisms produce an electrical current by respiring with an anode as electron acceptor. These organisms apply flavin molecules as cofactors to facilitate one-electron transfer catalyzed by the terminal reductases and in some cases as endogenous electron shuttles.

RESULTS: In the model organism Shewanella oneidensis, riboflavin production and excretion trigger a specific biofilm formation response that is initiated at a specific threshold concentration, similar to canonical quorum-sensing molecules. Riboflavin-mediated messaging is based on the overexpression of the gene encoding the putrescine decarboxylase speC which leads to posttranscriptional overproduction of proteins involved in biofilm formation. Using a model of growth-dependent riboflavin production under batch and biofilm growth conditions, the number of cells necessary to produce the threshold concentration per time was deduced. Furthermore, our results indicate that specific retention of riboflavin in the biofilm matrix leads to localized concentrations, which by far exceed the necessary threshold value.

CONCLUSION: This study describes a new quorum-sensing mechanism in S. oneidensis. Biofilm formation of S. oneidensis is induced by low concentrations of riboflavin resulting in an upregulation of the ornithine-decarboxylase speC. The results can be applied for the development of strains catalyzing increased current densities in bioelectrochemical systems.

RevDate: 2021-06-03

Mainetti T, Palmisano M, Rezzonico F, et al (2021)

Broad diversity of bacteria degrading 17ß-estradiol-3-sulfate isolated from river sediment and biofilm at a wastewater treatment plant discharge.

Archives of microbiology [Epub ahead of print].

Conjugated estrogens, such as 17β-estradiol-3-sulfate (E2-3S), can be released into aquatic environments through wastewater treatment plants (WWTP). There, they are microbiologically degraded into free estrogens, which can have harmful effects on aquatic wildlife. Here, the degradation of E2-3S in environmental samples taken upstream, downstream and at the effluent of a WWTP was assessed. Sediment and biofilm samples were enriched for E2-3S-degrading microorganisms, yielding a broad diversity of bacterial isolates, including known and novel degraders of estrogens. Since E2-3S-degrading bacteria were also isolated in the sample upstream of the WWTP, the WWTP does not influence the ability of the microbial community to degrade E2-3S.

RevDate: 2021-06-03

AlMojel N, AbdulAzees PA, Lamb EM, et al (2021)

Determining growth inhibition of Candida albicans biofilm on denture materials after application of an organoselenium-containing dental sealant.

The Journal of prosthetic dentistry pii:S0022-3913(21)00225-0 [Epub ahead of print].

STATEMENT OF PROBLEM: Denture stomatitis is a chronic inflammatory condition caused by the formation of Candida albicans biofilm on denture bases. It is associated with aggravating intraoral pain, itching, and burning sensations. It can also potentiate cardiovascular diseases and aspiration pneumonia. The problem has thus far eluded efficient, toxic-free, and cost-effective solutions.

PURPOSE: The purpose of this in vitro study was to investigate the effectiveness of organoselenium to inhibit the formation of C. albicans biofilm on the surface of acrylic resin denture base materials when it is either incorporated into the acrylic resin material or coated on the denture surface as a light-polymerized surface sealant.

MATERIAL AND METHODS: Sixty heat-polymerized polymethyl methacrylate disks were fabricated and assigned to 4 groups (n=15): disks coated with a light-polymerized organoselenium-containing enamel surface sealant (DenteShield), disks impregnated with 0.5% organoselenium (0.5% selenium), disks impregnated with 1% organoselenium (1% selenium), and disks without organoselenium (control). C. albicans biofilm was grown on each disk which had been placed in a well of the microtiter plate containing 1-mL brain heart infusion broth inoculated with C. albicans. The plates were incubated aerobically at 37 °C for 48 hours. A confocal laser scanning microscope was used to determine the biofilm thickness, biomass, and live/dead cell ratio. Biofilm morphology was examined with scanning electron microscopy, whereas microbial viability was quantified by the spread plate method. The data were analyzed by using ANOVA and Tukey-Kramer multiple comparisons (α=.05).

RESULTS: The microbial viability, biofilm thickness, biofilm biomass, and live/dead cell ratio were lower (P<.001) on disks in the test groups (DenteShield, 0.5% selenium, 1% selenium) when compared with the control group, with these variables being lowest in the 0.5% selenium and 1% selenium groups. The 0.5% selenium and 1% selenium groups did not differ significantly from each other in any of the variables (P>.05). Scanning electron microscope images showed inhibition of both biofilm growth and yeast to hyphae transition in the DenteShield, 0.5% selenium, and 1% selenium groups, with visible disruption of the biofilm morphology.

CONCLUSIONS: The present study demonstrated that organoselenium, whether incorporated into or coated on the surface of an acrylic resin denture base material, has the potential to inhibit Candida albicans biofilm growth on denture surfaces and as such can be clinically useful for the prevention of denture stomatitis.

RevDate: 2021-06-02

Lahiri D, Nag M, Dutta B, et al (2021)

Antibiofilm and Anti-Quorum sensing Activities of Eugenol and Linalool From Ocimum tenuiflorum against Pseudomonas aeruginosa Biofilm.

Journal of applied microbiology [Epub ahead of print].

AIMS: Determination of the ability of two bioactive compounds, namely Eugenol and Linalool, purified from leaves of Ocimum tenuiflorum for eradication of biofilm produced by Pseudomonas aeruginosa.

METHODS AND RESULTS: The phyto-extract of Ocimum tenuiflorum (KT), a common ethno-botanical plant of India, was purified through HPLC, and was analyzed using UV spectroscopy and GC-MS. Eugenol and Linalool were found to be the most active amongst all phytocompounds present in phytoextract and showed a significant reduction in the viability of sessile cells of Pseudomonas aeruginosa and the minimum revival after withdrawal of phyto-challenge. They could bring about notable reduction in the protein and carbohydrate content of exopolysaccharide of biofilm . Eugenol and linalool could affect the synthesis of QS proteins like lasA and lasB as well as virulence factors such as pyocyanin, and rhamnolipids, which seriously hamper the formation of biofilm. The biofilm framework was extremely affected by the phytocompounds through the reduction of protein and carbohydrate content of EPS. Another interesting find out was that they brought about maximum inhibition to the genomic DNA and RNA content. The studies were supported by in-silico interaction between eugenol and linalool with the QS proteins. The antibiofilm efficacies of eugenol, linalool and phytoextract (KT) were further confirmed by microscopic studies with scanning electron (SEM), Atomic Force (AFM) and Fluorescence confocal (FCM) microscopic studies.

CONCLUSIONS: The phytocompounds are proved to be more effective than conventional antibiotics in inhibiting the biofilm forming sessile cells and can be used as a replacement for antibiotic.

Pure eugenol extracted from common basil leaves can be used as a safe substitute for common antibiotic for treatment of chronic infections caused by Pseudomonas aeruginosa. It will be cost effective, devoid of notable side effects and will not generate antibiotic resistance in host body.

RevDate: 2021-06-02

He YZ, Xu Y, Sun J, et al (2021)

Novel Plasmid-Borne Fimbriae-Associated Gene Cluster Participates in Biofilm Formation in Escherichia coli.

Microbial drug resistance (Larchmont, N.Y.) [Epub ahead of print].

This study reported the involvement of a gene cluster from a conjugative plasmid in the biofilm formation of Escherichia coli. We used a novel EZ-Tn5 transposon technique to generate a transposon library and used arbitrarily primed PCR to detect the insertion sites in biofilm formation-deficient mutants. To validate the function of candidate biofilm formation genes, the genes were cloned into plasmid pBluescript II SK (+) and transformed into E. coil DH5α. Biofilm production from the transformants was then assessed by phenotypic biofilm formation using Crystal Violet staining and microscopy. A total of 3,000 transposon mutants of E. coli DH5α-p253 were screened, of which 28 were found to be deficient in biofilm formation. Further characterization revealed that 24/28 mutations were detected with their insertions in chromosome, while the remaining 4 mutations were evidenced that the functional genes for biofilm formation were harbored in the plasmid. Interestingly, the plasmid sequencing showed that these four transposon mutations were all inserted into a fimbriae-associated gene cluster (fim-cluster). This fim-cluster is a hybrid segment spanning a 7,949 bp sequence, with a terminal inverted repeat sequence and two coding regions. In summary, we performed a high-efficiency screening to a library constructed with the EZ-Tn5-based transposon approach and identified the gene clusters responsible for the biofilm production of E. coli, especially the genes harbored in the plasmid. Further studies are needed to understand the spread of this novel plasmid-mediated biofilm formation gene in clinical E. coli isolates and the clinical impacts.

RevDate: 2021-06-02

Noble K, Lu J, Guevara MA, et al (2021)

Group B Streptococcus cpsE Is Required for Serotype V Capsule Production and Aids in Biofilm Formation and Ascending Infection of the Reproductive Tract during Pregnancy.

ACS infectious diseases [Epub ahead of print].

Group B Streptococcus (GBS) is an encapsulated Gram-positive pathogen that causes ascending infections of the reproductive tract during pregnancy. The capsule of this organism is a critical virulence factor that has been implicated in a variety of cellular processes to promote pathogenesis. Primarily comprised of carbohydrates, the GBS capsule and its synthesis is driven by the capsule polysaccharide synthesis (cps) operon. The cpsE gene within this operon encodes a putative glycosyltransferase that is responsible for the transfer of a Glc-1-P from UDP-Glc to an undecaprenyl lipid molecule. We hypothesized that the cpsE gene product is important for GBS virulence and ascending infection during pregnancy. Our work demonstrates that a GBS cpsE mutant secretes fewer carbohydrates, has a reduced capsule, and forms less biofilm than the wild-type parental strain. We show that, compared to the parental strain, the ΔcpsE deletion mutant is more readily taken up by human placental macrophages and has a significantly attenuated ability to invade and proliferate in the mouse reproductive tract. Taken together, these results demonstrate that the cpsE gene product is an important virulence factor that aids in GBS colonization and invasion of the gravid reproductive tract.

RevDate: 2021-06-02

Singh R, Ren Z, Shi Y, et al (2021)

Affordable oral healthcare: Dental biofilm disruption using chloroplast made enzymes with chewing gum delivery.

Plant biotechnology journal [Epub ahead of print].

Current approaches for oral health care rely on procedures that are unaffordable to impoverished populations, whereas aerosolized droplets in the dental clinic and poor oral hygiene may contribute to spread of several infectious diseases including COVID-19 pandemic, requiring new solutions for dental biofilm/plaque treatment at home. Plant cells have been used to produce monoclonal antibodies or antimicrobial peptides for topical applications to decrease colonization of pathogenic microbes on dental surface. Therefore, we investigated an affordable method for dental biofilm disruption by expressing lipase, dextranase or mutanase in plant cells via the chloroplast genome. Antibiotic resistance gene used to engineer foreign genes into the chloroplast genome were subsequently removed using direct repeats flanking the aadA gene and enzymes were successfully expressed in marker free lettuce transplastomic lines. Equivalent enzyme units of plant-derived lipase performed better than purified commercial enzymes against biofilms, specifically targeting fungal hyphae formation. Combination of lipase with dextranase and mutanase suppressed biofilm development by degrading the biofilm matrix, with concomitant reduction of bacterial and fungal accumulation. In chewing gum tablets formulated with freeze dried plant cells, expressed protein was stable up to three years at ambient temperature and was efficiently released in a time dependent manner using a mechanical chewing simulator device. Development of edible plant cells expressing enzymes eliminates the need for purification and cold-chain transportation, providing a potential translatable therapeutic approach. Biofilm-disruption through plant enzymes and chewing gum-based delivery offers an effective and affordable dental biofilm control in patients at home, with minimal oral care access.

RevDate: 2021-06-02

Liu L, Huang L, Yu D, et al (2021)

FeS2 nanoparticles decorated carbonized Luffa cylindrica as biofilm substrates for fabricating high performance biosensors.

Talanta, 232:122416.

A high-performance microbial biosensor was fabricated with a reasonably designed biofilm substrate, where the aerogel of carbonized Luffa cylindrica (LC) was used as the scaffold for loading biofilm and FeS2 nanoparticles (FeS2NPs) were employed to modify this aerogel (FeS2NPs/GelLC). The fabricated FeS2NPs/GelLC exhibited a spring-like structure similar with that of the raw LC, which facilitated the linkage of the scaffold and promoted its mechanical strength, and further prolonged the service period of the as-prepared biosensor from few days to two months. Meanwhile, the introduced FeS2NPs improved the microbial electron transfer of the biofilm and causing an increase in the sensor's signals from 155.0 ± 2.6 to 352.0 ± 17.1 nA and a decrease in the detection limit from 0.95 to 0.38 mg O L-1 (S/N = 3) for the detection of glucose-glutamic acid (GGA). More important, the FeS2NPs had been demonstrated to have the capability for modulating a persistent shift of the microbial community with organic pollutant biodegradability. Compared with the GelLC, the FeS2NPs/GelLC exhibited a promising performance for measuring the synthetic sewage and real water samples in BOD assay and an increasing inhibition-ratio for detecting 3,5-dichlorophenol (DCP) in toxicity assay. Based on the vast resource and renewability of LC, this work pave a new avenue for developing high-performance microbial biosensors that are expected to be the engineering production.

RevDate: 2021-06-02

Spiess S, Kucera J, Seelajaroen H, et al (2021)

Impact of Carbon Felt Electrode Pretreatment on Anodic Biofilm Composition in Microbial Electrolysis Cells.

Biosensors, 11(6): pii:bios11060170.

Sustainable technologies for energy production and storage are currently in great demand. Bioelectrochemical systems (BESs) offer promising solutions for both. Several attempts have been made to improve carbon felt electrode characteristics with various pretreatments in order to enhance performance. This study was motivated by gaps in current knowledge of the impact of pretreatments on the enrichment and microbial composition of bioelectrochemical systems. Therefore, electrodes were treated with poly(neutral red), chitosan, or isopropanol in a first step and then fixed in microbial electrolysis cells (MECs). Four MECs consisting of organic substance-degrading bioanodes and methane-producing biocathodes were set up and operated in batch mode by controlling the bioanode at 400 mV vs. Ag/AgCl (3M NaCl). After 1 month of operation, Enterococcus species were dominant microorganisms attached to all bioanodes and independent of electrode pretreatment. However, electrode pretreatments led to a decrease in microbial diversity and the enrichment of specific electroactive genera, according to the type of modification used. The MEC containing isopropanol-treated electrodes achieved the highest performance due to presence of both Enterococcus and Geobacter. The obtained results might help to select suitable electrode pretreatments and support growth conditions for desired electroactive microorganisms, whereby performance of BESs and related applications, such as BES-based biosensors, could be enhanced.

RevDate: 2021-06-02

Pinel I, Biškauskaitė R, Pal'ová E, et al (2021)

Assessment of the Impact of Temperature on Biofilm Composition with a Laboratory Heat Exchanger Module.

Microorganisms, 9(6): pii:microorganisms9061185.

Temperature change over the length of heat exchangers might be an important factor affecting biofouling. This research aimed at assessing the impact of temperature on biofilm accumulation and composition with respect to bacterial community and extracellular polymeric substances. Two identical laboratory-scale plate heat exchanger modules were developed and tested. Tap water supplemented with nutrients was fed to the two modules to enhance biofilm formation. One "reference" module was kept at 20.0 ± 1.4 °C and one "heated" module was operated with a counter-flow hot water stream resulting in a bulk water gradient from 20 to 27 °C. Biofilms were grown during 40 days, sampled, and characterized using 16S rRNA gene amplicon sequencing, EPS extraction, FTIR, protein and polysaccharide quantifications. The experiments were performed in consecutive triplicate. Monitoring of heat transfer resistance in the heated module displayed a replicable biofilm growth profile. The module was shown suitable to study the impact of temperature on biofouling formation. Biofilm analyses revealed: (i) comparable amounts of biofilms and EPS yield in the reference and heated modules, (ii) a significantly different protein to polysaccharide ratio in the EPS of the reference (5.4 ± 1.0%) and heated modules (7.8 ± 2.1%), caused by a relatively lower extracellular sugar production at elevated temperatures, and (iii) a strong shift in bacterial community composition with increasing temperature. The outcomes of the study, therefore, suggest that heat induces a change in biofilm bacterial community members and EPS composition, which should be taken into consideration when investigating heat exchanger biofouling and cleaning strategies. Research potential and optimization of the heat exchanger modules are discussed.

RevDate: 2021-06-02

Gomes IB, Lemos M, Fernandes S, et al (2021)

The Effects of Chemical and Mechanical Stresses on Bacillus cereus and Pseudomonas fluorescens Single- and Dual-Species Biofilm Removal.

Microorganisms, 9(6): pii:microorganisms9061174.

Biofilm control is mainly based on chemical disinfection, without a clear understanding of the role of the biocides and process conditions on biofilm removal. This study aims to understand the effects of a biocide (benzyldimethyldodecyl ammonium chloride-BDMDAC) and mechanical treatment (an increase of shear stress -τw) on single- and dual-species biofilms formed by Bacillus cereus and Pseudomonas fluorescens on high-density polyethene (HDPE). BDMDAC effects were initially assessed on bacterial physicochemical properties and initial adhesion ability. Then, mature biofilms were formed on a rotating cylinder reactor (RCR) for 7 days to assess the effects of chemical and mechanical treatments, and the combination of both on biofilm removal. The results demonstrated that the initial adhesion does not predict the formation of mature biofilms. It was observed that the dual-species biofilms were the most susceptible to BDMDAC exposure. The exposure to increasing τw emphasised the mechanical stability of biofilms, as lower values of τw&nbsp;(1.66 Pa) caused high biofilm erosion and higher τw values (17.7 Pa) seem to compress the remaining biofilm. In general, the combination of BDMDAC and the mechanical treatment was synergic in increasing biofilm removal. However, these were insufficient to cause total biofilm removal (100%; an average standard deviation of 11% for the method accuracy should be considered) from HDPE.

RevDate: 2021-06-02

Czajkowska J, Junka A, Hoppe J, et al (2021)

The Co-Culture of Staphylococcal Biofilm and Fibroblast Cell Line: The Correlation of Biological Phenomena with Metabolic NMR1 Footprint.

International journal of molecular sciences, 22(11): pii:ijms22115826.

Staphylococcus aureus is one of the most prevalent pathogens associated with several types of biofilm-based infections, including infections of chronic wounds. Mature staphylococcal biofilm is extremely hard to eradicate from a wound and displays a high tendency to induce recurring infections. Therefore, in the present study, we aimed to investigate in vitro the interaction between S. aureus biofilm and fibroblast cells searching for metabolites that could be considered as potential biomarkers of critical colonization and infection. Utilizing advanced microscopy and microbiological methods to examine biofilm formation and the staphylococcal infection process, we were able to distinguish 4 phases of biofilm development. The analysis of staphylococcal biofilm influence on the viability of fibroblasts allowed us to pinpoint the moment of critical colonization-12 h post contamination. Based on the obtained model we performed a metabolomics analysis by 1H NMR spectroscopy to provide new insights into the pathophysiology of infection. We identified a set of metabolites related to the switch to anaerobic metabolism that was characteristic for staphylococcal biofilm co-cultured with fibroblast cells. The data presented in this study may be thus considered a noteworthy but preliminary step in the direction of developing a new, NMR-based tool for rapid diagnosing of infection in a chronic wound.

RevDate: 2021-06-02

Ridyard KE, J Overhage (2021)

The Potential of Human Peptide LL-37 as an Antimicrobial and Anti-Biofilm Agent.

Antibiotics (Basel, Switzerland), 10(6): pii:antibiotics10060650.

The rise in antimicrobial resistant bacteria threatens the current methods utilized to treat bacterial infections. The development of novel therapeutic agents is crucial in avoiding a post-antibiotic era and the associated deaths from antibiotic resistant pathogens. The human antimicrobial peptide LL-37 has been considered as a potential alternative to conventional antibiotics as it displays broad spectrum antibacterial and anti-biofilm activities as well as immunomodulatory functions. While LL-37 has shown promising results, it has yet to receive regulatory approval as a peptide antibiotic. Despite the strong antimicrobial properties, LL-37 has several limitations including high cost, lower activity in physiological environments, susceptibility to proteolytic degradation, and high toxicity to human cells. This review will discuss the challenges associated with making LL-37 into a viable antibiotic treatment option, with a focus on antimicrobial resistance and cross-resistance as well as adaptive responses to sub-inhibitory concentrations of the peptide. The possible methods to overcome these challenges, including immobilization techniques, LL-37 delivery systems, the development of LL-37 derivatives, and synergistic combinations will also be considered. Herein, we describe how combination therapy and structural modifications to the sequence, helicity, hydrophobicity, charge, and configuration of LL-37 could optimize the antimicrobial and anti-biofilm activities of LL-37 for future clinical use.

RevDate: 2021-06-02

Andrade NC, Laranjo M, Costa MM, et al (2021)

Virulence Factors in Staphylococcus Associated with Small Ruminant Mastitis: Biofilm Production and Antimicrobial Resistance Genes.

Antibiotics (Basel, Switzerland), 10(6): pii:antibiotics10060633.

Small ruminant mastitis is a serious problem, mainly caused by Staphylococcus spp. Different virulence factors affect mastitis pathogenesis. The aim of this study was to investigate virulence factors genes for biofilm production and antimicrobial resistance to β-lactams and tetracyclines in 137 staphylococcal isolates from goats (86) and sheep (51). The presence of coa, nuc, bap, icaA, icaD, blaZ, mecA, mecC, tetK, and tetM genes was investigated. The nuc gene was detected in all S. aureus isolates and in some coagulase-negative staphylococci (CNS). None of the S. aureus isolates carried the bap gene, while 8 out of 18 CNS harbored this gene. The icaA gene was detected in S. aureus and S. warneri, while icaD only in S. aureus. None of the isolates carrying the bap gene harbored the ica genes. None of the biofilm-associated genes were detected in 14 isolates (six S. aureus and eight CNS). An association was found between Staphylococcus species and resistance to some antibiotics and between antimicrobial resistance and animal species. Nine penicillin-susceptible isolates exhibited the blaZ gene, questioning the reliability of susceptibility testing. Most S. aureus isolates were susceptible to tetracycline, and no cefazolin or gentamycin resistance was detected. These should replace other currently used antimicrobials.

RevDate: 2021-06-02

Paulitsch-Fuchs AH, Wolrab L, Eck N, et al (2021)

TiAl6V4 Alloy Surface Modifications and Their Impact on Biofilm Development of S. aureus and S. epidermidis.

Journal of functional biomaterials, 12(2): pii:jfb12020036.

One of the most serious complications following joint replacement surgeries are periprosthetic infections (PIs) arising from the adhesion of bacteria to the artificial joint. Various types of titanium-aluminum-vanadium (TiAl6V4) alloy surface modifications (coatings with silver (Ag), titanium nitride (TiN), pure titanium (cpTi), combinations of cpTi and hydroxyapatite (HA), combinations of cpTi and tricalcium phosphate (TCP), and a rough-blasted surface of TiAl6V4) have been investigated to assess their effects on biofilm development. Biofilms were grown, collected, and analyzed after 48 h to measure their protein and glucose content and the cell viability. Biofilm-associated genes were also monitored after 48 h of development. There was a distinct difference in the development of staphylococcal biofilms on the surfaces of the different types of alloy. According to the findings of this study, the base alloy TiAl6V4 and the TiN-coated surface are the most promising materials for biofilm reduction. Rough surfaces are most favorable when it comes to bacterial infections because they allow an easy attachment of pathogenic organisms. Of all rough surfaces tested, rough-blasted TiAl6V4 was the most favorable as an implantation material; all the other rough surfaces showed more distinct signs of inducing the development of biofilms which displayed higher protein and polysaccharide contents. These results are supported by RT-qPCR measurements of biofilm associated genes for Staphylococcus aureus (icaA, icaC, fnbA, fnbB, clfB, atl) and Staphylococcus epidermidis (atle, aap).

RevDate: 2021-06-02

Jayathilaka EHTT, Rajapaksha DC, Nikapitiya C, et al (2021)

Antimicrobial and Anti-Biofilm Peptide Octominin for Controlling Multidrug-Resistant Acinetobacter baumannii.

International journal of molecular sciences, 22(10): pii:ijms22105353.

Acinetobacter baumannii is a serious nosocomial pathogen with multiple drug resistance (MDR), the control of which has become challenging due to the currently used antibiotics. Our main objective in this study is to determine the antibacterial and antibiofilm activities of the antimicrobial peptide, Octominin, against MDR A. baumannii and derive its possible modes of actions. Octominin showed significant bactericidal effects at a low minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of 5 and 10 µg/mL, respectively. Time-kill kinetic analysis and bacterial viability tests revealed that Octominin showed a concentration-dependent antibacterial activity. Field-emission scanning electron microscopy (FE-SEM) analysis revealed that Octominin treatment altered the morphology and membrane structure of A. baumannii. Propidium iodide (PI) and reactive oxygen species (ROS) generation assays showed that Octominin increased the membrane permeability and ROS generation in A. baumannii, thereby causing bacterial cell death. Further, a lipopolysaccharides (LPS) binding assay showed an Octominin concentration-dependent LPS neutralization ability. Biofilm formation inhibition and eradication assays further revealed that Octominin inhibited biofilm formation and showed a high biofilm eradication activity against A. baumannii. Furthermore, up to a concentration of 100 µg/mL, Octominin caused no hemolysis and cell viability changes in mammalian cells. An in vivo study in zebrafish showed that the Octominin-treated group had a significantly higher relative percentage survival (54.1%) than the untreated group (16.6%). Additionally, a reduced bacterial load and fewer alterations in histological analysis confirmed the successful control of A. baumannii by Octominin in vivo. Collectively, these data suggest that Octominin exhibits significant antibacterial and antibiofilm activities against the multidrug-resistant A. baumannii, and this AMP can be developed further as a potent AMP for the control of antibiotic resistance.

RevDate: 2021-06-02

Wu S, Liu Y, Lei L, et al (2021)

An Antisense yycF RNA Modulates Biofilm Organization of Methicillin-Resistant Staphylococcus aureus and Pathogenicity in a Rat Model of Osteomyelitis.

Antibiotics (Basel, Switzerland), 10(5): pii:antibiotics10050603.

Staphylococcus aureus (S. aureus) is one of most common opportunistic pathogens and is attributed to several human infections. The increasing incidence of methicillin-resistant S. aureus (MRSA) is a serious clinical threat for osteomyelitis crisis. The YycFG two-component system of S. aureus regulates genes associated with biofilm formation. To investigate the potential role of an antisense yycF RNA in the regulation of transcription levels of yycF and associated effects on biofilm formation and pathogenicity, antisense yycF (ASyycF) RNA was detected by RT-PCR and 5' RACE assays. ASyycF overexpression mutants were constructed, and the biofilm biomass was determined by crystal violet microtiter assay and scanning electron microscopy (SEM). Quantitative RT-PCR and Western blotting analyses were used to detect whether ASyycF overexpression inhibited the transcription and translation of biofilm-related genes. Then, a rat tibial infective model was used to evaluate the pathogenicity of ASyycF overexpression in vivo. ASyycF transcription led to reductions in YycF production and biofilm formation. Overexpression of ASyycF inhibited the transcription and translation of biofilm-related genes. The sensitivity to vancomycin was improved in ASyycF-overexpressing MRSA. Furthermore, ASyycF inhibited MRSA invasion in a rat tibial infection model. From this study, the expression of the YycF protein was found to be inversely correlated with different levels of ASyycF transcription. The biofilm biomass and pathogenicity decreased in the ASyycF-overexpressing mutant. Thus, the current evidence may support ASyycF as a supplementary strategy for managing S. aureus and MRSA infections.

RevDate: 2021-06-02

Konduri R, Saiabhilash CR, S Shivaji (2021)

Biofilm-Forming Potential of Ocular Fluid Staphylococcus aureus and Staphylococcus epidermidis on Ex Vivo Human Corneas from Attachment to Dispersal Phase.

Microorganisms, 9(6): pii:microorganisms9061124.

The biofilm-forming potential of Staphylococcus aureus and Staphylococcus epidermidis, isolated from patients with Endophthalmitis, was monitored using glass cover slips and cadaveric corneas as substrata. Both the ocular fluid isolates exhibited biofilm-forming potential by the Congo red agar, Crystal violet and 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-(phenylamino) carbonyl-2H-tetra-zolium hydroxide (XTT) methods. Confocal microscopy demonstrated that the thickness of the biofilm increased from 4-120 h of biofilm formation. Scanning electron microscopic studies indicated that the biofilms grown on cover slips and ex vivo corneas of both the isolates go through an adhesion phase at 4 h followed by multilayer clumping of cells with intercellular connections and copious amounts of extracellular polymeric substance. Clumps subsequently formed columns and eventually single cells were visible indicative of dispersal phase. Biofilm formation was more rapid when the cornea was used as a substratum. In the biofilms grown on corneas, clumping of cells, formation of 3D structures and final appearance of single cells indicative of dispersal phase occurred by 48 h compared to 96-120 h when biofilms were grown on cover slips. In the biofilm phase, both were several-fold more resistant to antibiotics compared to planktonic cells. This is the first study on biofilm forming potential of ocular fluid S. aureus and S. epidermidis on cadaveric cornea, from attachment to dispersal phase of biofilm formation.

RevDate: 2021-06-02

Carzaniga T, Falchi FA, Forti F, et al (2021)

Different csrA Expression Levels in C versus K-12 E. coli Strains Affect Biofilm Formation and Impact the Regulatory Mechanism Presided by the CsrB and CsrC Small RNAs.

Microorganisms, 9(5): pii:microorganisms9051010.

Escherichia coli C is a strong biofilm producer in comparison to E. coli K-12 laboratory strains due to higher expression of the pgaABCD operon encoding the enzymes for the biosynthesis of the extracellular polysaccharide poly-β-1,6-N-acetylglucosamine (PNAG). The pgaABCD operon is negatively regulated at the post-transcriptional level by two factors, namely CsrA, a conserved RNA-binding protein controlling multiple pathways, and the RNA exonuclease polynucleotide phosphorylase (PNPase). In this work, we investigated the molecular bases of different PNAG production in C-1a and MG1655 strains taken as representative of E. coli C and K-12 strains, respectively. We found that pgaABCD operon expression is significantly lower in MG1655 than in C-1a; consistently, CsrA protein levels were much higher in MG1655. In contrast, we show that the negative effect exerted by PNPase on pgaABCD expression is much stronger in C-1a than in MG1655. The amount of CsrA and of the small RNAs CsrB, CsrC, and McaS sRNAs regulating CsrA activity is dramatically different in the two strains, whereas PNPase level is similar. Finally, the compensatory regulation acting between CsrB and CsrC in MG1655 does not occur in E. coli C. Our results suggest that PNPase preserves CsrA-dependent regulation by indirectly modulating csrA expression.

RevDate: 2021-06-02

Grande R, S Carradori (2021)

Novel Biologically Active Molecules, Biomaterials, and Nanoparticles for Microbial Biofilm Control in Human Medicine.

Molecules (Basel, Switzerland), 26(9): pii:molecules26092749.

The aim of the present special issue, proposed by two Co-Guest Editors with expertise in Clinical Microbiology and Medicinal Chemistry, is to collect and disseminate some of the most significant and innovative contributions focused on biofilm removal strategies, based on the use of natural or synthetic compounds/molecules/peptides or nanoparticles as well as biofilm formation inhibition aimed at both the control and monitoring of biofilm infections in medicine, food, industry, and natural environments [...].

RevDate: 2021-06-02

Hao S, Yang D, Zhao L, et al (2021)

EGCG-Mediated Potential Inhibition of Biofilm Development and Quorum Sensing in Pseudomonas aeruginosa.

International journal of molecular sciences, 22(9): pii:ijms22094946.

Pseudomonas aeruginosa (P. aeruginosa), one of the dangerous multidrug resistance pathogens, orchestrates virulence factors production through quorum sensing (QS). Since the exploration of QS inhibitors, targeting virulence to circumvent bacterial pathogenesis without causing significant growth inhibition is a promising approach to treat P. aeruginosa infections. The present study has evaluated the anti-QS and anti-infective activity of epigallocatechin-3-gallate (EGCG), a bioactive ingredient of the traditional green tea, against P. aeruginosa. EGCG showed significant inhibitory effects on the development of biofilm, protease, elastase activity, swimming, and swarming motility, which was positively related to the production of C4-AHL. The expression of QS-related and QS-regulated virulence factors genes was also evaluated. Quantitative PCR analysis showed that EGCG significantly reduced the expression of las, rhl, and PQS genes and was highly correlated with the alterations of C4-AHL production. In-vivo experiments demonstrated that EGCG treatment reduced P. aeruginosa pathogenicity in Caenorhabditis elegans (C. elegans). EGCG increased the survival of C. elegans by 23.25%, 30.04%, and 36.35% in a dose-dependent manner. The findings of this study strongly suggest that EGCG could be a potential candidate for QS inhibition as an anti-virulence compound against bacterial infection.

RevDate: 2021-06-02

Walczak M, Michalska-Sionkowska M, Olkiewicz D, et al (2021)

Potential of Carvacrol and Thymol in Reducing Biofilm Formation on Technical Surfaces.

Molecules (Basel, Switzerland), 26(9): pii:molecules26092723.

Polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), and stainless steel (SS) are commonly used in medicine and food production technologies. During contact with microorganisms on the surface of these materials, a microbial biofilm is formed. The biofilm structure is difficult to remove and promotes the development of pathogenic bacteria. For this reason, the inhibition of biofilm formation in medical and food production environments is very important. For this purpose, five naturally occurring compounds were used for antimicrobial screening tests. The two with the best antimicrobial properties were chosen to inhibit the biofilm formation of Staphylococcus aureus and Pseudomonas aeruginosa. After 3 days of exposure, thymol reduced the amount of biofilm of Pseudomonas aeruginosa within the range of 70-77% and 52-75% for Staphylococcus aureus. Carvacrol inhibited the formation of biofilms by up to 74-88% for Pseudomonas aeruginosa and up to 86-100% for Staphylococcus aureus. Those phenols decreased the enzyme activity of the biofilm by up to 40-100%. After 10 days of exposure to thymol, biofilm formation was reduced by 80-100% for Pseudomonas aeruginosa and by about 79-100% for Staphylococcus aureus. Carvacrol reduced the amount of biofilm by up to 91-100% for Pseudomonas aeruginosa and up to 95-100% for Staphylococcus aureus.

RevDate: 2021-06-02

Swolana D, Kępa M, Kabała-Dzik A, et al (2021)

Sensitivity of Staphylococcal Biofilm to Selected Compounds of Plant Origin.

Antibiotics (Basel, Switzerland), 10(5): pii:antibiotics10050607.

Staphylococcus epidermidis is a bacterium that belongs to the human microbiota. It is most plentiful on the skin, in the respiratory system, and in the human digestive tract. Moreover, it is the most frequently isolated microorganism belonging to the group of Coagulase Negative Staphylococci (CoNS). In recent years, it has been recognized as an important etiological factor of mainly nosocomial infections and infections related to the cardiovascular system. On the other hand, Staphylococcus aureus, responsible for in-hospital and out-of-hospital infections, is posing an increasing problem for clinicians due to its growing resistance to antibiotics. Biofilm produced by both of these staphylococcal species in the course of infection significantly impedes therapy. The ability to produce biofilm hinders the activity of chemotherapeutic agents-the only currently available antimicrobial therapy. This also causes the observed significant increase in bacterial resistance. For this reason, we are constantly looking for new substances that can neutralize microbial cells. In the present review, 58 substances of plant origin with antimicrobial activity against staphylococcal biofilm were replaced. Variable antimicrobial efficacy of the substances was demonstrated, depending on the age of the biofilm. An increase in the activity of the compounds occurred in proportion to increasing their concentration. Appropriate use of the potential of plant-derived compounds as an alternative to antibiotics may represent an important direction of change in the support of antimicrobial therapy.

RevDate: 2021-06-02

Fasciana T, Ciammaruconi A, Gentile B, et al (2021)

Draft Genome Sequence and Biofilm Production of a Carbapenemase-Producing Klebsiella pneumoniae (KpR405) Sequence Type 405 Strain Isolated in Italy.

Antibiotics (Basel, Switzerland), 10(5): pii:antibiotics10050560.

Rapid identification and characterization of multidrug-resistant Klebsiella pneumoniae strains is essential to diagnose severe infections in patients. In clinical routine practice, K. pneumoniae is frequently identified and characterized for outbreak investigation. Pulsed-field gel electrophoresis or multilocus sequence typing could be used, but, unfortunately, these methods are time-consuming, laborious, expensive, and do not provide any information about the presence of resistance and virulence genes. In recent years, the decreasing cost of next-generation sequencing and its easy use have led to it being considered a useful method, not only for outbreak surveillance but also for rapid identification and evaluation, in a single step, of virulence factors and resistance genes. Carbapenem-resistant strains of K. pneumoniae have become endemic in Italy, and in these strains the ability to form biofilms, communities of bacteria fixed in an extracellular matrix, can defend the pathogen from the host immune response as well as from antibiotics, improving its persistence in epithelial tissues and on medical device surfaces.

RevDate: 2021-06-02

Asghari E, Kiel A, Kaltschmidt BP, et al (2021)

Identification of Microorganisms from Several Surfaces by MALDI-TOF MS: P. aeruginosa Is Leading in Biofilm Formation.

Microorganisms, 9(5): pii:microorganisms9050992.

New ecological trends and changes in consumer behavior are known to favor biofilm formation in household appliances, increasing the need for new antimicrobial materials and surfaces. Their development requires laboratory-cultivated biofilms, or biofilm model systems (BMS), which allow for accelerated growth and offer better understanding of the underlying formation mechanisms. Here, we identified bacterial strains in wildtype biofilms from a variety of materials from domestic appliances using matrix-assisted laser desorption/ionization-time of flight mass spectroscopy (MALDI-TOF-MS). Staphylococci and pseudomonads were identified by MALDI-TOF-MS as the main genera in the habitats and were analyzed for biofilm formation using various in vitro methods. Standard quantitative biofilm assays were combined with scanning electron microscopy (SEM) to characterize biofilm formation. While Pseudomonas putida, a published lead germ, was not identified in any of the collected samples, Pseudomonas aeruginosa was found to be the most dominant biofilm producer. Water-born Pseudomonads were dominantly found in compartments with water contact only, such as in detergent compartment and detergent enemata. Furthermore, materials in contact with the washing load are predominantly colonized with bacteria from the human.

RevDate: 2021-06-02

Renard A, Diene SM, Courtier-Martinez L, et al (2021)

12/111phiA Prophage Domestication Is Associated with Autoaggregation and Increased Ability to Produce Biofilm in Streptococcus agalactiae.

Microorganisms, 9(6): pii:microorganisms9061112.

CC17 Streptococcus agalactiae carrying group-A prophages is increasingly responsible for neonatal infections. To investigate the impact of the genetic features of a group-A prophage, we first conducted an in silico analysis of the genome of 12/111phiA, a group-A prophage carried by a strain responsible for a bloodstream infection in a parturient. This revealed a Restriction Modification system, suggesting a prophage maintenance strategy and five ORFs of interest for the host and encoding a type II toxin antitoxin system RelB/YafQ, an endonuclease, an S-adenosylmethionine synthetase MetK, and an StrP-like adhesin. Using the WT strain cured from 12/111phiA and constructing deleted mutants for the ORFs of interest, and their complemented mutants, we demonstrated an impact of prophage features on growth characteristics, cell morphology and biofilm formation. Our findings argue in favor of 12/111phiA domestication by the host and a role of prophage features in cell autoaggregation, glycocalyx and biofilm formation. We suggest that lysogeny may promote GBS adaptation to the acid environment of the vagina, consequently colonizing and infecting neonates.

RevDate: 2021-06-02

Jabłońska-Wawrzycka A, Rogala P, Czerwonka G, et al (2021)

Tuning Anti-Biofilm Activity of Manganese(II) Complexes: Linking Biological Effectiveness of Heteroaromatic Complexes of Alcohol, Aldehyde, Ketone, and Carboxylic Acid with Structural Effects and Redox Activity.

International journal of molecular sciences, 22(9): pii:ijms22094847.

The constantly growing resistance of bacteria to antibiotics and other antibacterial substances has led us to an era in which alternative antimicrobial therapies are urgently required. One promising approach is to target bacterial pathogens using metal complexes. Therefore, we investigated the possibility of utilizing series of manganese(II) complexes with heteroaromatic ligands: Alcohol, aldehyde, ketone, and carboxylic acid as inhibitors for biofilm formation of Pseudomonas aeruginosa. To complete the series mentioned above, Mn-dipyCO-NO3 with dipyridin-2-ylmethanone (dipyCO) was isolated, and then structurally (single-crystal X-ray analysis) and physicochemically characterized (FT-IR, TG, CV, magnetic susceptibility). The antibacterial activity of the compounds against representative Gram-negative and Gram-positive bacteria was also evaluated. It is worth highlighting that the results of the cytotoxicity assays performed (MTT, DHI HoloMonitorM4) indicate high cell viability of the human fibroblast (VH10) in the presence of the Mn(II) complexes. Additionally, the inhibition effect of catalase activity by the complexes was studied. This paper focused on such aspects as studying different types of intermolecular interactions in the crystals of the Mn(II) complexes as well as their possible effect on anti-biofilm activity, the structure-activity relationship of the Mn(II) complexes, and regularity between the electrochemical properties of the Mn(II) complexes and anti-biofilm activity.

RevDate: 2021-06-02

Samuggam S, Chinni SV, Mutusamy P, et al (2021)

Green Synthesis and Characterization of Silver Nanoparticles Using Spondias mombin Extract and Their Antimicrobial Activity against Biofilm-Producing Bacteria.

Molecules (Basel, Switzerland), 26(9): pii:molecules26092681.

Multidrug resistant bacteria create a challenging situation for society to treat infections. Multidrug resistance (MDR) is the reason for biofilm bacteria to cause chronic infection. Plant-based nanoparticles could be an alternative solution as potential drug candidates against these MDR bacteria, as many plants are well known for their antimicrobial activity against pathogenic microorganisms. Spondias mombin is a traditional plant which has already been used for medicinal purposes as every part of this plant has been proven to have its own medicinal values. In this research, the S. mombin extract was used to synthesise AgNPs. The synthesized AgNPs were characterized and further tested for their antibacterial, reactive oxygen species and cytotoxicity properties. The characterization results showed the synthesized AgNPs to be between 8 to 50 nm with -11.52 of zeta potential value. The existence of the silver element in the AgNPs was confirmed with the peaks obtained in the EDX spectrometry. Significant antibacterial activity was observed against selected biofilm-forming pathogenic bacteria. The cytotoxicity study with A. salina revealed the LC50 of synthesized AgNPs was at 0.81 mg/mL. Based on the ROS quantification, it was suggested that the ROS production, due to the interaction of AgNP with different bacterial cells, causes structural changes of the cell. This proves that the synthesized AgNPs could be an effective drug against multidrug resistant bacteria.

RevDate: 2021-06-02

Woźniak A, Kruszewska B, Pierański MK, et al (2021)

Antimicrobial Photodynamic Inactivation Affects the Antibiotic Susceptibility of Enterococcus spp. Clinical Isolates in Biofilm and Planktonic Cultures.

Biomolecules, 11(5): pii:biom11050693.

Enterococcus faecium and Enterococcus faecalis are opportunistic pathogens that can cause a vast variety of nosocomial infections. Moreover, E. faecium belongs to the group of ESKAPE microbes, which are the main cause of hospital-acquired infections and are especially difficult to treat because of their resistance to many antibiotics. Antimicrobial photodynamic inactivation (aPDI) represents an alternative to overcome multidrug resistance problems. This process requires the simultaneous presence of oxygen, visible light, and photosensitizing compounds. In this work, aPDI was used to resensitize Enterococcus spp. isolates to antibiotics. Antibiotic susceptibility testing according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommendations was combined with synergy testing methods recommended by the American Society for Microbiology. Two clinical isolates, E. faecalis and E. faecium, were treated with a combination of aPDI utilizing rose bengal (RB) or fullerene (FL) derivative as photosensitizers, antimicrobial blue light (aBL), and 10 recommended antibiotics. aPDI appeared to significantly impact the survival rate of both isolates, while aBL had no significant effect. The synergy testing results differed between strains and utilized methods. Synergy was observed for RB aPDI in combination with gentamycin, ciprofloxacin and daptomycin against E. faecalis. For E. faecium, synergy was observed between RB aPDI and gentamycin or ciprofloxacin, while for RB aPDI with vancomycin or daptomycin, antagonism was observed. A combination of FL aPDI gives a synergistic effect against E. faecalis only with imipenem. Postantibiotic effect tests for E. faecium demonstrated that this isolate exposed to aPDI in combination with gentamycin, streptomycin, tigecycline, doxycycline, or daptomycin exhibits delayed growth in comparison to untreated bacteria. The results of synergy testing confirmed the effectiveness of aPDI in resensitization of the bacteria to antibiotics, which presents great potential in the treatment of infections caused by multidrug-resistant strains.

RevDate: 2021-06-01

Frazão Câmara JV, Araujo TT, Mendez DAC, et al (2021)

Effect of a sugarcane cystatin on the profile and viability of microcosm biofilm and on dentin demineralization.

Archives of microbiology [Epub ahead of print].

To analyze the effect of a sugarcane cystatin (CaneCPI-5) on the microbial profile and viability, as well as on the prevention of dentin demineralization using a microcosm biofilm model. Ninety bovine dentine specimens were divided into five experimental groups according with the solution they were treated for 60 s: (1) PBS (negative control), (2) 0.12% chlorhexidine (positive control), (3) Fluoride (500 ppm F, as NaF), (4) 0.025 mg/ml CaneCPI-5, and (5) 0.05 mg/ml CaneCPI-5. Specimens were incubated with inoculum (McBain's saliva plus human saliva) in the first 8 h, and from then on, they were exposed to McBain saliva containing sucrose and daily treated (60 s) with the solutions for 5 days. Resazurin and colony-forming unit counting assays were performed. Dentin demineralization was measured by transverse micro-radiography (TMR). 0.12% chlorhexidine significantly reduced the metabolic activity of the microcosm biofilm in relation to the negative control and treated groups (p < 0.01). CHX and F significantly reduced the counts of total microorganisms, mutans group streptococci, and lactobacilli when compared with the negative control. None of the treatments was able to significantly reduce dentin demineralization in comparison with the negative control. In the model evaluated, CaneCPI-5 neither altered the microcosm biofilm profile and viability nor protected dentin against demineralization.

RevDate: 2021-06-01

Sapireddy V, Katuri KP, Muhammad A, et al (2021)

Competition of two highly specialized and efficient acetoclastic electroactive bacteria for acetate in biofilm anode of microbial electrolysis cell.

NPJ biofilms and microbiomes, 7(1):47.

Maintaining functional stability of microbial electrolysis cell (MEC) treating wastewater depends on maintaining functional redundancy of efficient electroactive bacteria (EAB) on the anode biofilm. Therefore, investigating whether efficient EAB competing for the same resources (electron donor and acceptor) co-exist at the anode biofilm is key for the successful application of MEC for wastewater treatment. Here, we compare the electrochemical and kinetic properties of two efficient acetoclastic EAB, Geobacter sulfurreducens (GS) and Desulfuromonas acetexigens (DA), grown as monoculture in MECs fed with acetate. Additionally, we monitor the evolution of DA and GS in co-culture MECs fed with acetate or domestic wastewater using fluorescent in situ hybridization. The apparent Monod kinetic parameters reveal that DA possesses higher jmax (10.7 ± 0.4 A/m2) and lower KS, app (2 ± 0.15 mM) compared to GS biofilms (jmax: 9.6 ± 0.2 A/m2 and KS, app: 2.9 ± 0.2 mM). Further, more donor electrons are diverted to the anode for respiration in DA compared to GS. In acetate-fed co-culture MECs, DA (98% abundance) outcompete GS for anode-dependent growth. In contrast, both EAB co-exist (DA: 55 ± 2%; GS: 24 ± 1.1%) in wastewater-fed co-culture MECs despite the advantage of DA over GS based on kinetic parameters alone. The co-existence of efficient acetoclastic EAB with high current density in MECs fed with wastewater is significant in the context of functional redundancy to maintain stable performance. Our findings also provide insight to future studies on bioaugmentation of wastewater-fed MECs with efficient EAB to enhance performance.

RevDate: 2021-06-01

Manandhar S, Singh A, Varma A, et al (2021)

Phenotypic and genotypic characterization of biofilm producing clinical coagulase negative staphylococci from Nepal and their antibiotic susceptibility pattern.

Annals of clinical microbiology and antimicrobials, 20(1):41.

BACKGROUND: Coagulase-negative staphylococci (CNS) survive as commensals of skin, anterior nares and external canals of human and were regarded as non-infectious pathogens. However, they are emerging as a major cause of nosocomial infectious due to their ability to form biofilms and high resistance to several classes of antibiotics. This study examines the biofilm forming abilities of 214 clinical CNS isolates using phenotypic and genotypic methods, and determines their antibiotic susceptibility patterns.

METHODS: A total of 214 clinical isolates collected from different clinical samples were identified as CNS and their antibiotic susceptibility determined by CLSI guidelines. The biofilm forming ability of all isolates was determined by three phenotypic methods; Congo red agar (CRA) method, tube adherence method (TM) and tissue culture plate (TCP) method and by genotypic method for the detection of icaAD genes.

RESULTS: Among all the isolates, S. epidermidis (57.5%) was found the most frequently, followed by S. saprophyticus (18.7%), S. haemolyticus (11.2%), S. hominis (7%), and S. capitis (5.6%). Antibiotic susceptibility pattern demonstrated 91.6% isolates were resistant to penicillin and 66.8% to cefoxitin while 91.1% isolates were susceptible to chloramphenicol. Constitutive and inducible clindamycin resistant phenotype as measured by D-test was seen among 28% and 14.5% of isolates respectively. Tissue culture plate method detected biofilm production in 42.1% isolate followed by 31.8% through tube method while 20.1% isolates were found to produce slime in Congo red agar method. The genotypic assay revealed presence of icaA and icaD genes in 19.2% isolates.

CONCLUSION: The study shows a high prevalence of biofilm formation and inducible clindamycin resistance in CNS isolates, indicating the importance of in-vitro biofilm production test and D-test in routine laboratory diagnostics. Implementation of efficient diagnostic techniques for detection of biofilm production in clinical samples can help manage staphylococcal infections and minimize risks of treatment failures in hospitals.

RevDate: 2021-05-31

Zhou Y, Li R, Guo B, et al (2021)

Cometabolism accelerated simultaneous ammoxidation and organics mineralization in an oxygen-based membrane biofilm reactor treating greywater under low dissolved oxygen conditions.

The Science of the total environment, 789:147898 pii:S0048-9697(21)02969-7 [Epub ahead of print].

Carbon/nitrogen ratio is an important parameter during the biological wastewater treatment. Our study emphasizes revealing the mechanisms of chemical oxygen demand/total nitrogen (COD/TN) ratio dependent improved greywater (GW) treatment in an oxygen based membrane biofilm reactor (O2-MBfR). Results showed that reducing COD/TN ratio from 40 to 20 g COD/g N by supplementing NH4Cl to GW improved the relative abundance of genera related to LAS-biodegradation (from 8.39% to 35.7%), nitrification (from 0.20% to 0.62%) and denitrification (from 3.01% to 7.59%). Reducing COD/TN ratio also led to an increase in the ammonia monooxygenase (AMO) activity (from 7.56 to 10.2 mg N/g VSS-h), as well as improved ammoxidation and linear alkylbenzene sulfonate (LAS) mineralization although the dissolved oxygen (DO) concentration and pH decreased. Much higher NH4+ - N at lower COD/TN ratio (10 units) led to lower DO (0.13 ± 0.01 mg/L) and pH (6.72 ± 0.02), but the continuously increased AMO activity (up to 12.9 mg N/g VSS-h) enabled the cometabolism of ammoxidation and LAS mineralization, leading to the efficient removal of organics and nitrogen under the low DO condition.

RevDate: 2021-05-31

Ghergab A, Mohanan N, Saliga G, et al (2021)

The effect of polyhydroxyalkanoates in Pseudomonas chlororaphis PA23 biofilm formation, stress endurance, and interaction with the protozoan predator Acanthamoeba castellanii.

Canadian journal of microbiology [Epub ahead of print].

Pseudomonas chlororaphis PA23 is a biocontrol agent capable of protecting canola against the fungal pathogen Sclerotinia sclerotiorum. In addition to producing antifungal compounds, this bacterium synthesizes and accumulates polyhydroxyalkanoate (PHA) polymers as carbon and energy storage compounds. Because the role of PHA in PA23 physiology is currently unknown, we investigated the impact of this polymer on stress resistance, adherence to surfaces, and interaction with the protozoan predator Acanthamoeba castellanii. Three PHA biosynthesis mutants were created, PA23phaC1, PA23phaC1ZC2, and PA23phaC1ZC2D, which accumulated reduced PHA. Our phenotypic assays revealed that PA23phaC1ZC2D produced less phenazine (PHZ) compared with the wild type (WT) and the phaC1 and phaC1ZC2 mutants. All three mutants exhibited enhanced sensitivity to UV irradiation, starvation, heat stress, cold stress, and hydrogen peroxide. Moreover, motility, exopolysaccharide production, biofilm formation, and root attachment were increased in strains with reduced PHA levels. Interaction studies with the amoeba A. castellanii revealed that the WT and the phaC1 and phaC1ZC2 mutants were consumed less than the phaC1ZC2D mutant, likely due to decreased PHZ production by the latter. Collectively these findings indicate that PHA accumulation enhances PA23 resistance to a number of stresses in vitro, which could improve the environmental fitness of this bacterium in hostile environments.

RevDate: 2021-05-31

Carvalho TS, Muçolli D, Eick S, et al (2021)

Salivary Pellicle Modification with Grape-seed Extract: In Vitro Study on the Effect on Bacterial Adhesion and Biofilm Formation.

Oral health & preventive dentistry, 19(1):301-309.

PURPOSE: Grape-seed extract (GSE) contains polyphenols that readily adhere to proteins and modify the acquired enamel pellicle (AEP). The first step in biofilm formation is bacterial adhesion to the AEP-covered enamel. The aim of this in vitro study was to test whether AEP modification with GSE, fluoride (F-), or their combination (GSE+F-) modulates bacterial adhesion, biofilm metabolism and composition, or cariogenic demineralisation of the enamel.

MATERIALS AND METHODS: The study comprised 3 parts: 1) single-strain Streptococcus gordonii species, 2) a five-species biofilm model, or 3) biofilm (re-)formation using the five-species biofilm model after removal of initial biofilm with toothbrushing. Human whole-mouth stimulated saliva was used to form an AEP on human enamel specimens. The AEP was incubated in water (control), or modified with GSE, F-, or GSE+F-. Bacterial adhesion, biofilm diversity, metabolic activity, biofilm mass, and cariogenic demineralisation (surface hardness) of enamel were assessed after incubation in bacterial broths after 4 h or 22 h. Differences between groups were analysed with one-way ANOVA and post-hoc Bonferroni tests.

RESULTS: GSE and GSE+F- statistically significantly decreased single-strain S. gordonii adhesion, but had no relevant influence when the five-species biofilm model was used. In the biofilm (re-)formation model, GSE reduced bacterial adhesion compared to GSE+F-, while F- caused less cariogenic demineralisation than was found in the control group.

CONCLUSION: AEP modified with GSE retards S. gordonii adhesion, but it does not influence the formation, metabolism and composition of a cariogenic multi-species biofilm.

RevDate: 2021-05-31

Kearns KL, Boyd JD, ME Grady (2020)

Biofilm rupture by laser-induced stress waves increases with loading amplitude, independent of location.

ACS applied bio materials, 3(3):1426-1433.

Integral to the production of safe and biocompatible medical devices is to determine the interfacial properties that affect or control strong biofilm adhesion. The laser spallation technique has recently emerged as an advantageous method to quantify biofilm adhesion across candidate biomedical surfaces. However, there is a possibility that membrane tension is a factor that contributes to the stress required to separate biofilm and substrate. In that case, the stress amplitude, controlled by laser fluence, that initiates biofilm rupture would vary systematically with location on the biofilm. Film rupture, also known as spallation, occurs when film material is ejected during stress wave loading. In order to determine effects of membrane tension on the laser spallation process, we present a protocol that measures spall size with increasing laser fluence (variable fluence) and with respect to distance from the biofilm centroid (iso-fluence). Streptococcus mutans biofilms on titanium substrates serve as our model system. A total of 185 biofilm loading locations are analyzed in this study. We demonstrate that biofilm spall size increases monotonically with laser fluence and apply our procedure to failure of non-biological films. In iso-fluence experiments, no correlation is found between biofilm spall size and loading location, thus providing evidence that membrane tension does not play a dominant role in biofilm adhesion measurements. We recommend our procedure as a straightforward method to determine membrane effects in the measurement of adhesion of biological films on substrate surfaces via the laser spallation technique.

RevDate: 2021-05-31

Gayani B, Dilhari A, Kottegoda N, et al (2021)

Reduced Crystalline Biofilm Formation on Superhydrophobic Silicone Urinary Catheter Materials.

ACS omega, 6(17):11488-11496.

Crystalline biofilm formation in indwelling urinary catheters is a serious health problem as it creates a barrier for antibacterial coatings. This emphasizes the failure of antibacterial coatings that do not have a mechanism to reduce crystal deposition on catheter surfaces. In this study, trifluoropropyl spray-coated polydimethylsiloxane (TFP-PDMS) has been employed as an antibiofilm forming surface without any antibacterial agent. Here, TFP was coated on half-cured PDMS using the spray coating technique to obtain a durable superhydrophobic coating for a minimum five cycles of different sterilization methods. The crystalline biofilm-forming ability of Proteus mirabilis in artificial urine, under static and flow conditions, was assessed on a TFP-PDMS surface. In comparison to the commercially available silver-coated latex and silicone catheter surfaces, TFP-PDMS displayed reduced bacterial attachment over 14 days. Moreover, the elemental analysis determined by atomic absorption spectroscopy and energy-dispersive X-ray analysis revealed that the enhanced antibiofilm forming ability of TFP-PDMS was due to the self-cleaning activity of the surface. We believe that this modified surface will significantly reduce biofilm formation in indwelling urinary catheters and further warrant future clinical studies.

RevDate: 2021-05-31

Srinivasan R, Santhakumari S, Poonguzhali P, et al (2021)

Bacterial Biofilm Inhibition: A Focused Review on Recent Therapeutic Strategies for Combating the Biofilm Mediated Infections.

Frontiers in microbiology, 12:676458.

Biofilm formation is a major concern in various sectors and cause severe problems to public health, medicine, and industry. Bacterial biofilm formation is a major persistent threat, as it increases morbidity and mortality, thereby imposing heavy economic pressure on the healthcare sector. Bacterial biofilms also strengthen biofouling, affecting shipping functions, and the offshore industries in their natural environment. Besides, they accomplish harsh roles in the corrosion of pipelines in industries. At biofilm state, bacterial pathogens are significantly resistant to external attack like antibiotics, chemicals, disinfectants, etc. Within a cell, they are insensitive to drugs and host immune responses. The development of intact biofilms is very critical for the spreading and persistence of bacterial infections in the host. Further, bacteria form biofilms on every probable substratum, and their infections have been found in plants, livestock, and humans. The advent of novel strategies for treating and preventing biofilm formation has gained a great deal of attention. To prevent the development of resistant mutants, a feasible technique that may target adhesive properties without affecting the bacterial vitality is needed. This stimulated research is a rapidly growing field for applicable control measures to prevent biofilm formation. Therefore, this review discusses the current understanding of antibiotic resistance mechanisms in bacterial biofilm and intensely emphasized the novel therapeutic strategies for combating biofilm mediated infections. The forthcoming experimental studies will focus on these recent therapeutic strategies that may lead to the development of effective biofilm inhibitors than conventional treatments.

RevDate: 2021-05-31

Stuermer EK, Plattfaut I, Dietrich M, et al (2021)

In vitro Activity of Antimicrobial Wound Dressings on P. aeruginosa Wound Biofilm.

Frontiers in microbiology, 12:664030.

The treatment of acute and chronic infected wounds with residing biofilm still poses a major challenge in medical care. Interactions of antimicrobial dressings with bacterial load, biofilm matrix and the overall protein-rich wound microenvironment remain insufficiently studied. This analysis aimed to extend the investigation on the efficacy of a variety of antimicrobial dressings using an in vitro biofilm model (lhBIOM) mimicking the specific biofilm-environment in human wounds. Four wound dressings containing polyhexanide (PHMB), octendine di-hydrochloride (OCT), cadexomer-iodine (C-IOD) or ionic silver (AG) were compared regarding their antimicrobial efficacy. Quantitative analysis was performed using a quantitative suspension method, separately assessing remaining microbial counts within the solid biofilm as well as the dressing eluate (representing the absorbed wound exudate). Dressing performance was tested against P. aeruginosa biofilms over the course of 6 days. Scanning electron microscopy (SEM) was used to obtain qualitative visualization on changes in biofilm structure. C-IOD demonstrated superior bacterial reduction. In comparison it was the only dressing achieving a significant reduction of more than 7 log10 steps within 3 days. Neither the OCT- nor the AG-containing dressing exerted a distinct and sustained antimicrobial effect. PHMB achieved a non-significant microbicidal effect (1.71 ± 0.31 log10 steps) at day 1. Over the remaining course (6 days) it demonstrated a significant microbistatic effect compared to OCT, AG and the control. Quantitative results in the dressing eluate correlate with those of the solid biofilm model. Overall, AG- and OCT-containing dressings did not achieve the expected anti-biofilm efficacy, while C-IOD performed best. Chemical interaction with the biofilms extrapolymeric substance (EPS), visualized in the SEM, and dressing configuration (agent concentration and release pattern) are suspected to be responsible. The unexpected low and diverse results of the tested antimicrobial dressings indicate a necessity to rethink non-debridement anti-biofilm therapy. Focussing on the combination of biofilm-disruptive (for EPS structure) and antimicrobial (for residing microorganisms) features, as with C-IOD, using dehydration and iodine, appears reasonably complementary and an optimal solution, as suggested by the here presented in vitro data.

RevDate: 2021-05-30

Cheng Z, Jiang X, Cui Z, et al (2021)

The characteristic of electrode of degradation of bio-electrochemical system based on in-situ ultrasonic monitoring: Biofilm and ion precipitation.

The Science of the total environment, 789:147987 pii:S0048-9697(21)03058-8 [Epub ahead of print].

Electrode interface behavior is a decisive factor affecting the performance of bio-electrochemical systems, and traditional monitoring methods cannot provide real-time feedback. Therefore, in situ ultrasonic monitoring was performed to continuously monitor the formation process of electroactive biofilm and salt precipitation on the cathode surface. The results showed that biofilm was attached to the cathode surface first. Then, Ca2+ and Mg2+ precipitation gradually invaded the biofilm and accumulated between the cathode and the biofilm. The electrochemical performance of the biofilm adhesion and initial ion invasion process was improved. However, the electrochemical performance of the precipitation layer was decreased, while the operation time increases. In this paper, based on the air cathode scaling analyzing a new method for monitoring the electrode interface of bio-electrochemical system was provided, and the performance was recovered by using reverse electric field.

RevDate: 2021-05-29

He Y, Abdi M, Trindade GF, et al (2021)

Exploiting Generative Design for 3D Printing of Bacterial Biofilm Resistant Composite Devices.

Advanced science (Weinheim, Baden-Wurttemberg, Germany) [Epub ahead of print].

As the understanding of disease grows, so does the opportunity for personalization of therapies targeted to the needs of the individual. To bring about a step change in the personalization of medical devices it is shown that multi-material inkjet-based 3D printing can meet this demand by combining functional materials, voxelated manufacturing, and algorithmic design. In this paper composite structures designed with both controlled deformation and reduced biofilm formation are manufactured using two formulations that are deposited selectively and separately. The bacterial biofilm coverage of the resulting composites is reduced by up to 75% compared to commonly used silicone rubbers, without the need for incorporating bioactives. Meanwhile, the composites can be tuned to meet user defined mechanical performance with ±10% deviation. Device manufacture is coupled to finite element modelling and a genetic algorithm that takes the user-specified mechanical deformation and computes the distribution of materials needed to meet this under given load constraints through a generative design process. Manufactured products are assessed against the mechanical and bacterial cell-instructive specifications and illustrate how multifunctional personalization can be achieved using generative design driven multi-material inkjet based 3D printing.

RevDate: 2021-05-29

Choudhary D, CJ Cassaro (2021)

Digging deeper in the biofilm.

Nature reviews. Microbiology [Epub ahead of print].

RevDate: 2021-05-28

Usmani Y, Ahmed A, Faizi S, et al (2021)

Antimicrobial and biofilm inhibiting potential of an amide derivative [N-(2', 4'-dinitrophenyl)-3β-hydroxyurs-12-en-28-carbonamide] of ursolic acid by modulating membrane potential and quorum sensing against colistin resistant Acinetobacter baumannii.

Microbial pathogenesis pii:S0882-4010(21)00269-2 [Epub ahead of print].

Acinetobacter baumannii is Gram-negative, an opportunistic pathogen responsible for life-threatening ventilator-associated pneumonia. World Health Organization (WHO) enlisted it as a priority pathogen for which therapeutic options need speculations. Biofilm further benefits this pathogen and aids 100-1000 folds more resistant against antimicrobials and the host immune system. In this study, ursolic acid (1) and its amide derivatives (2-4) explored for their antimicrobial and antibiofilm potential against colistin-resistant A. baumannii (CRAB) reference and clinical strains. Viability, crystal violet, microscopic, and gene expression assays further detailed the active compounds' antimicrobial and biofilm inhibition potential. Compound 4 [N-(2',4'-dinitrophenyl)-3β-hydroxyurs-12-en-28-carbonamide)], a synthetic amide derivate of ursolic acid significantly inhibits bacterial growth with MIC in the range of 78-156 μg/mL against CRAB isolates. This compound failed to completely kill the CRAB isolates even at 500 μg/mL concentration, suggesting the compound's anti-virulence and bacteriostatic nature. Short and prolonged exposure of 4 inhibited or delayed the bacterial growth at sub MIC, MIC, and 2× MIC, as evident in time-kill and post-antibacterial assay. It significantly inhibited and eradicated >70% of biofilm formation at MIC and sub MIC levels compared to colistin required in high concentrations. Microscopic analysis showed disintegrated biofilm after treatment with the 4 further strengthened its antibiofilm potential. Atomic force microscopy (AFM) hinted the membrane disrupting effect of 4 at MIC's. Further it was confirmed by DiBAC4 using fluorescence-activating cells sorting (FACS), suggesting a depolarized membrane at MIC. Gene expression analysis also supported our data as it showed reduced expression of biofilm-forming (bap) and quorum sensing (abaR) genes after treatment with sub MIC of 4. The results suggest that 4 significantly inhibit bacterial growth and biofilm mode of colistin-resistant A. baumannii. Thus, further studies are required to decipher the complete mechanism of action to develop 4 as a new pharmacophore against A. baumannii.

RevDate: 2021-05-28

Diepoltová A, Konečná K, Janďourek O, et al (2021)

Study of the impact of cultivation conditions and peg surface modification on the in vitro biofilm formation of Staphylococcus aureus and Staphylococcus epidermidis in a system analogous to the Calgary biofilm device.

Journal of medical microbiology, 70(5):.

Introduction.Staphylococcus aureus (SA) and Staphylococcus epidermidis (SE) are the most common pathogens from the genus Staphylococcus causing biofilm-associated infections. Generally, biofilm-associated infections represent a clinical challenge. Bacteria in biofilms are difficult to eradicate due to their resistance and serve as a reservoir for recurring persistent infections.Gap Statement. A variety of protocols for in vitro drug activity testing against staphylococcal biofilms have been introduced. However, there are often fundamental differences. All these differences in methodical approaches can then be reflected in the form of discrepancies between results.Aim. In this study, we aimed to develop optimal conditions for staphylococcal biofilm formation on pegs. The impact of peg surface modification was also studied.Methodology. The impact of tryptic soy broth alone or supplemented with foetal bovine serum (FBS) or human plasma (HP), together with the impact of the inoculum density of bacterial suspensions and the shaking versus the static mode of cultivation, on total biofilm biomass production in SA and SE reference strains was studied. The surface of pegs was modified with FBS, HP, or poly-l-lysine (PLL). The impact on total biofilm biomass was evaluated using the crystal violet staining method and statistical data analysis.Results. Tryptic soy broth supplemented with HP together with the shaking mode led to crucial potentiation of biofilm formation on pegs in SA strains. The SE strain did not produce biofilm biomass under the same conditions on pegs. Preconditioning of peg surfaces with FBS and HP led to a statistically significant increase in biofilm biomass formation in the SE strain.Conclusion. Optimal cultivation conditions for robust staphylococcal biofilm formation in vitro might differ among different bacterial strains and methodical approaches. The shaking mode and supplementation of cultivation medium with HP was beneficial for biofilm formation on pegs for SA (ATCC 29213) and methicillin-resistant SA (ATCC 43300). Peg conditioning with HP and PLL had no impact on biofilm formation in either of these strains. Peg coating with FBS showed an adverse effect on the biofilm formation of these strains. By contrast, there was a statistically significant increase in biofilm biomass production on pegs coated with FBS and HP for SE (ATCC 35983).

RevDate: 2021-05-28

He C, Sampers I, Van de Walle D, et al (2021)

Encapsulation of Lactobacillus in Low-Methoxyl Pectin-Based Microcapsules Stimulates Biofilm Formation: Enhanced Resistances to Heat Shock and Simulated Gastrointestinal Digestion.

Journal of agricultural and food chemistry [Epub ahead of print].

Encapsulation is a common approach to improve the bacterial survival of probiotics. In this study, two new low-methoxyl pectins (CMP-6 and CMP-8) were used as coating materials to produce microcapsules (MCs) for the encapsulation of Lactobacillus acidophilus LMG9433T, Lactobacillus casei LMG6904T, and Lactobacillus rhamnosus LMG25859. A fermentation test showed that encapsulation did not influence the fermentation ability of lactobacilli. The biofilm formation of encapsulated lactobacilli was stimulated when an in situ cultivation was conducted on MCs, which was verified by cryo-SEM observation. The resultant biofilm-forming MCs (BMCs) contained high-density bacterial cells (∼1010 CFU/mL). Compared to planktonic lactobacilli, pectin-based MCs showed significant protection for encapsulated lactobacilli from heat shock and simulated gastric digestion. Especially, benefiting from the biofilm formation, BMCs provided higher protection with enhanced resistance to heat shock, freeze-drying, and gastrointestinal digestion than MCs. Our result highlighted the superior bacterial resistances of biofilm-forming probiotics encapsulated in pectinate microcapsules.

RevDate: 2021-05-28

Ma J, Cheng X, Xu Z, et al (2021)

Structural mechanism for modulation of functional amyloid and biofilm formation by Staphylococcal Bap protein switch.

The EMBO journal [Epub ahead of print].

The Staphylococcal Bap proteins sense environmental signals (such as pH, [Ca2+ ]) to build amyloid scaffold biofilm matrices via unknown mechanisms. We here report the crystal structure of the aggregation-prone region of Staphylococcus aureus Bap which adopts a dumbbell-shaped fold. The middle module (MM) connecting the N-terminal and C-terminal lobes consists of a tandem of novel double-Ca2+ -binding motifs involved in cooperative interaction networks, which undergoes Ca2+ -dependent order-disorder conformational switches. The N-terminal lobe is sufficient to mediate amyloid aggregation through liquid-liquid phase separation and maturation, and subsequent biofilm formation under acidic conditions. Such processes are promoted by disordered MM at low [Ca2+ ] but inhibited by ordered MM stabilized by Ca2+ binding, with inhibition efficiency depending on structural integrity of the interaction networks. These studies illustrate a novel protein switch in pathogenic bacteria and provide insights into the mechanistic understanding of Bap proteins in modulation of functional amyloid and biofilm formation, which could be implemented in the anti-biofilm drug design.

RevDate: 2021-05-28

Weig AW, Barlock SL, O'Connor PM, et al (2021)

A scaffold hopping strategy to generate new aryl-2-amino pyrimidine MRSA biofilm inhibitors.

RSC medicinal chemistry, 12(2):293-296 pii:d0md00238k.

Infections that stem from bacterial biofilms are difficult to eradicate. Within a biofilm state, bacteria are upwards of 1000-fold more resistant to conventional antibiotics, necessitating the development of alternative approaches to treat biofilm-based infections. One such approach is the development of small molecule adjuvants that can inhibit/disrupt bacterial biofilms. When such molecules are paired with conventional antibiotics, these dual treatments present a combination approach to eradicate biofilm-based infections. Previously, we have demonstrated that small molecules containing either a 2-amino pyrimidine (2-AP) or a 2-aminoimidazole (2-AI) heterocycle are potent anti-biofilm agents. Herein, we now report a scaffold hopping strategy to generate new aryl 2-AP analogs that inhibit biofilm formation by methicillin-resistant Staphylococcus aureus (MRSA). These molecules also suppress colistin resistance in colistin resistant Klebsiella pneumoniae, lowering the minimum inhibitory concentration (MIC) by 32-fold.

RevDate: 2021-05-28

Fuchs A, Tripet BP, Ammons MCB, et al (2016)

Optimization of Metabolite Extraction Protocols for the Identification and Profiling of Small Molecule Metabolites from Planktonic and Biofilm Pseudomonas aeruginosa Cultures.

Current Metabolomics, 4(2):141-147.

Background: Metabolomics aims to characterize the metabolic phenotype and metabolic pathways utilized by microorganisms or other cellular systems. A crucial component to metabolomics research as it applies to microbial metabolism is the development of robust and reproducible methods for extraction of intracellular metabolites. The goal is to extract all metabolites in a non-biased and consistent manner; however, most methods used thus far are targeted to specific metabolite classes and use harsh conditions that may contribute to metabolite degradation. Metabolite extraction methodologies need to be optimized for each microorganism of interest due to different cellular characteristics contributing to lysis resistance.

Methods: Three cell pellet wash solutions were compared for the potential to influence intracellular metabolite leakage of P. aeruginosa. We also compared four different extraction methods using (i) methanol:chloroform (2:1); (ii) 50% methanol; (iii) 100% methanol; or (iv) 100% water to extract intracellular metabolites from P. aeruginosa planktonic and biofilm cultures.

Results: Intracellular metabolite extraction efficiency was found to be dependent on the extraction method and varies between microbial modes of growth. Methods using the 60% methanol wash produced the greatest amount of intracellular material leakage. Quantification of intracellular metabolites via 1H NMR showed that extraction protocols using 100% water or 50% methanol achieved the greatest extraction efficiencies, while addition of sonication to facilitate cell lysis to the 50% methanol extraction method resulted in at least a two-fold increase in signal intensities for approximately half of the metabolites identified. Phosphate buffered saline (PBS) was determined to be the most appropriate wash solution, yielding little intracellular metabolite leakage from cells.

Conclusion: We determined that washing in 1X PBS and extracting intracellular metabolites with 50% methanol is the most appropriate metabolite extraction protocol because (a) leakage is minimal; (b) a broad range of metabolites present at sufficiently high concentrations is detectable by NMR; and (c) this method proved suitable for metabolite extraction of both planktonic and biofilm P. aeruginosa cultures.

RevDate: 2021-05-28

Awadh AA, Kelly AF, Forster-Wilkins G, et al (2021)

Visualisation and biovolume quantification in the characterisation of biofilm formation in Mycoplasma fermentans.

Scientific reports, 11(1):11259.

The ability of mycoplasmas to persist on surfaces has been widely acknowledged, despite their fastidious nature. However, the organism's capability to form a recognisable biofilm structure has been identified more recently. In the current study Mycoplasma fermentans was found to adhere to the glass surface forming highly differentiated biofilm structures. The volumes of biofilm microcolonies were quantified and observed to be greater at late growth stage than those at early growth stage. The channel diameters within biofilms were measured with Scanning Electron Microscopy images and found to be consistent with the size observed in Confocal Laser Scanning Microscope images. The combination of imaging methods with 3D visualisation provides key findings that aid understanding of the mycoplasma biofilm formation and true biofilm architecture. The observations reported here provide better understanding of the persistence of these minimalist pathogens in nature and clinical settings.

RevDate: 2021-05-27

Victoria VM, Rocío C, Silvina E, et al (2021)

Biofilm formation by LEE-negative Shiga Toxin-Producing Escherichia coli strains.

Microbial pathogenesis pii:S0882-4010(21)00278-3 [Epub ahead of print].

Shiga toxin-producing Escherichia coli (STEC) include several serotypes isolated from cases of hemorrhagic colitis and hemolytic uremic syndrome. Although O157:H7 is the most predominant STEC serotype, more than 100 non-O157 serogroups cause diseases in humans. Some STEC carry a Locus of Enterocyte Effacement (LEE-positive); however, STEC that do not carry LEE (LEE-negative) have also been associated with illness, mainly those harbouring the Locus of Adhesion and Autoaggregation (LAA). LAA carry some genes such as hes, iha, tpsA, and agn43, related with pathogenicity. One of them is the ability to form biofilms on different environments, which can contaminate food and generate infections while protecting themselves against adverse conditions. Considering that LAA could be responsible for some adherence mechanisms, the aims of this study were to compare different serogroup of LEE-negative STEC strains in their ability to form biofilms and to evaluate the participation of some genes encoding in LAA. A total of 348 LEE-negative STEC was analyzed. The presence of hes, iha, tpsA and agn43 were determined by monoplex PCR. From them, 48 STEC strains belonging to serogroups O113, O130, O171, O174 and, O178 were assayed for their ability to form biofilm. The most prevalent genes detected were agn43 (72.1%) and tpsA (69.5%). The iha and hes genes were present in 63.7% and 54% of the strains, respectively. Although all STEC strains were able to form biofilm, it was found a high variability between them. The relation between the biofilm formation and the presence of each gene was not statistically significant, suggesting that biofilm formation is independent of the presence of those genes. Highlighting that there is no treatment for HUS, it is once again notable that prevention measures and control strategies to prevent biofilm formation are important factors in reducing STEC transmission.


ESP Quick Facts

ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

ESP Support

In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

ESP Rationale

Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

ESP Goal

In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

ESP Usage

Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

ESP Content

When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

ESP Help

Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

ESP Plans

With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.


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This is a must read book for anyone with an interest in invasion biology. The full title of the book lays out the author's premise — The New Wild: Why Invasive Species Will Be Nature's Salvation. Not only is species movement not bad for ecosystems, it is the way that ecosystems respond to perturbation — it is the way ecosystems heal. Even if you are one of those who is absolutely convinced that invasive species are actually "a blight, pollution, an epidemic, or a cancer on nature", you should read this book to clarify your own thinking. True scientific understanding never comes from just interacting with those with whom you already agree. R. Robbins

Electronic Scholarly Publishing
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Papers in Classical Genetics

The ESP began as an effort to share a handful of key papers from the early days of classical genetics. Now the collection has grown to include hundreds of papers, in full-text format.

Digital Books

Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).


ESP now offers a much improved and expanded collection of timelines, designed to give the user choice over subject matter and dates.


Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )