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Bibliography on: Biofilm

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ESP: PubMed Auto Bibliography 09 Apr 2020 at 01:34 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 pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2020-04-08

Karbysheva S, Di Luca M, Butini ME, et al (2020)

Comparison of sonication with chemical biofilm dislodgement methods using chelating and reducing agents: Implications for the microbiological diagnosis of implant associated infection.

PloS one, 15(4):e0231389 pii:PONE-D-19-27719.

The diagnosis of implant-associated infections is hampered due to microbial adherence and biofilm formation on the implant surface. Sonication of explanted devices was shown to improve the microbiological diagnosis by physical removal of biofilms. Recently, chemical agents have been investigated for biofilm dislodgement such as the chelating agent ethylenediaminetetraacetic acid (EDTA) and the reducing agent dithiothreitol (DTT). We compared the activity of chemical methods for biofilm dislodgement to sonication in an established in vitro model of artificial biofilm. Biofilm-producing laboratory strains of Staphylococcus epidermidis (ATCC 35984), S. aureus (ATCC 43300), E. coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 53278) were used. After 3 days of biofilm formation, porous glass beads were exposed to control (0.9% NaCl), sonication or chemical agents. Quantitative and qualitative biofilm analyses were performed by colony counting, isothermal microcalorimetry and scanning electron microscopy. Recovered colony counts after treatment with EDTA and DTT were similar to those after exposure to 0.9% NaCl for biofilms of S. epidermidis (6.3 and 6.1 vs. 6.0 log10 CFU/mL, S. aureus (6.4 and 6.3 vs. 6.3 log10 CFU/mL), E. coli (5.2 and 5.1 vs. 5.1 log10 CFU/mL and P. aeruginosa (5.1 and 5.2 vs. 5.0 log10 CFU/mL, respectively). In contrast, with sonication higher CFU counts were detected with all tested microorganisms (7.5, 7.3, 6.2 and 6.5 log10 CFU/mL, respectively) (p <0.05). Concordant results were observed with isothermal microcalorimetry and scanning electron microscopy. In conclusion, sonication is superior to both tested chemical methods (EDTA and DTT) for dislodgement of S. epidermidis, S. aureus, E. coli and P. aeruginosa biofilms. Future studies may evaluate potential additive effect of chemical dislodgement to sonication.

RevDate: 2020-04-08

McGivney E, Cederholm L, Barth A, et al (2020)

Rapid Physicochemical Changes in Microplastic Induced by Biofilm Formation.

Frontiers in bioengineering and biotechnology, 8:205.

Risk assessment of microplastic (MP) pollution requires understanding biodegradation processes and related changes in polymer properties. In the environment, there are two-way interactions between the MP properties and biofilm communities: (i) microorganisms may prefer some surfaces, and (ii) MP surface properties change during the colonization and weathering. In a 2-week experiment, we studied these interactions using three model plastic beads (polyethylene [PE], polypropylene [PP], and polystyrene [PS]) exposed to ambient bacterioplankton assemblage from the Baltic Sea; the control beads were exposed to bacteria-free water. For each polymer, the physicochemical properties (compression, crystallinity, surface chemistry, hydrophobicity, and surface topography) were compared before and after exposure under controlled laboratory conditions. Furthermore, we characterized the bacterial communities on the MP surfaces using 16S rRNA gene sequencing and correlated community diversity to the physicochemical properties of the MP. Significant changes in PE crystallinity, PP stiffness, and PS maximum compression were observed as a result of exposure to bacteria. Moreover, there were significant correlations between bacterial diversity and some physicochemical characteristics (crystallinity, stiffness, and surface roughness). These changes coincided with variation in the relative abundance of unique OTUs, mostly related to the PE samples having significantly higher contribution of Sphingobium, Novosphingobium, and uncultured Planctomycetaceae compared to the other test materials, whereas PP and PS samples had significantly higher abundance of Sphingobacteriales and Alphaproteobacteria, indicating possible involvement of these taxa in the initial biodegradation steps. Our findings demonstrate measurable signs of MP weathering under short-term exposure to environmentally relevant microbial communities at conditions resembling those in the water column. A systematic approach for the characterization of the biodegrading capacity in different systems will improve the risk assessment of plastic litter in aquatic environments.

RevDate: 2020-04-08

Shafeeq S, Wang X, Lünsdorf H, et al (2020)

Draft Genome Sequence of the Urinary Catheter Isolate Enterobacter ludwigii CEB04 with High Biofilm Forming Capacity.

Microorganisms, 8(4): pii:microorganisms8040522.

:Enterobacter ludwigii is a fermentative Gram-negative environmental species and accidental human pathogen that belongs to the Enterobacter cloacae complex with the general characteristics of the genus Enterobacter. The clinical isolate E. ludwigii CEB04 was derived from a urinary tract catheter of an individual not suffering from catheter-associated urinary tract infection. The draft genome sequence of the high biofilm forming E. ludwigii CEB04 was determined by PacBio sequencing. The chromosome of E. ludwigii CEB04 is comprised of one contig of 4,892,375 bps containing 4596 predicted protein-coding genes and 120 noncoding RNAs. E. ludwigii CEB04 harbors several antimicrobial resistance markers and has an extended cyclic-di-GMP signaling network compared to Escherichia coli K-12.

RevDate: 2020-04-08

Jouneghani RS, Castro AHF, Panda SK, et al (2020)

Antimicrobial Activity of Selected Banana Cultivars Against Important Human Pathogens, Including Candida Biofilm.

Foods (Basel, Switzerland), 9(4): pii:foods9040435.

Ten banana (Musa spp.) cultivars were studied for their antimicrobial properties. Three plant parts (corm, pseudostem and leaves) were collected separately and extracted with different solvents, viz., hexane, acetone, ethanol and water. The 50% inhibitory concentration (IC50) was evaluated using a broth microdilution assay. Eight human bacterial and one fungal pathogen were tested. Acetone and ethanol extract(s) often exhibited significant antimicrobial activity, while hexane extracts were less active. Aqueous extracts often showed microbial growth, possibly by endophytes. Leaf extracts were most active, followed by pseudostem, and corm was least active. All the tested banana cultivars were found to contain antimicrobials, as demonstrated by inhibition of selected human pathogens. However, cultivars such as Dole, Saba, Fougamou, Namwah Khom, Pelipita and Mbwazirume showed a broad-spectrum activity, inhibiting all tested pathogens. Other cultivars such as Petit Naine and Kluai Tiparot showed a narrow-spectrum activity, including antibiofilm activity against Candida albicans. Our results support the use of different parts of banana plants in traditional human medicine for infections, including diarrhea and dysentery, and some sexually transmitted diseases, as well as for packaging spoilable materials like food.

RevDate: 2020-04-08

Chen L, Tang ZY, Cui SY, et al (2020)

Biofilm Production Ability, Virulence and Antimicrobial Resistance Genes in Staphylococcus aureus from Various Veterinary Hospitals.

Pathogens (Basel, Switzerland), 9(4): pii:pathogens9040264.

:Staphylococcus aureus (S. aureus) is one of the most clinically important zoonotic pathogens, but an understanding of the prevalence, biofilm formulation ability, virulence, and antimicrobial resistance genes of S. aureus from veterinary hospitals is lacking. By characterizing S. aureus in different origins of veterinary hospitals in Guangzhou, China, in 2019, we identified with the presence of S. aureus in pets (17.1%), veterinarians (31.7%), airborne dust (19.1%), environmental surfaces (4.3%), and medical device surfaces (10.8%). Multilocus sequence typing (MLST) and Staphylococcus protein A (spa) typing analyses demonstrated methicillin-sensitive S. aureus (MSSA) ST398-t571, MSSA ST188-t189, and methicillin-resistant S. aureus (MRSA) ST59-t437 were the most prevalent lineage. S. aureus with similar pulsed-field gel electrophoresis (PFGE) types distributed widely in different kinds of samples. The crystal violet straining assays revealed 100% (3/3) of MRSA ST59 and 81.8% (9/11) of MSSA ST188 showed strong biofilm formulation ability, whereas other STs (ST1, ST5, ST7, ST15, ST88, ST398, ST3154 and ST5353) showed weak biofilm production ability. Polymerase chain reaction (PCR) confirmed the most prevalent leucocidin, staphylococcal enterotoxins, ica operon, and adhesion genes were lukD-lukE (49.0%), sec-sel (15.7%), icaA-icaB-icaC-icaR (100.0%), and fnbB-cidA-fib-ebps-eno (100.0%), respectively. Our study showed that the isolates with strong biofilm production ability had a higher prevalence in clfA, clfB, fnbA and sdrC genes compared to the isolates with weak biofilm production ability. Furthermore, 2 ST1-MRSA isolates with tst gene and 1 ST88-MSSA isolate with lukS/F-PV gene were detected. In conclusion, the clonal dissemination of S. aureus of different origins in veterinary hospitals may have occurred; the biofilm production capacity of S. aureus is strongly correlated with ST types; some adhesion genes such as clfA, clfB, fnbA,andsdrC may pose an influence on biofilm production ability and the emergence of lukS/F-PV and tst genes in S. aureus from veterinary hospitals should raise our vigilance.

RevDate: 2020-04-08

Karkowska-Kuleta J, Surowiec M, Gogol M, et al (2020)

Peptidylarginine Deiminase of Porphyromonas gingivalis Modulates the Interactions between Candida albicans Biofilm and Human Plasminogen and High-Molecular-Mass Kininogen.

International journal of molecular sciences, 21(7): pii:ijms21072495.

Microorganisms that create mixed-species biofilms in the human oral cavity include, among others, the opportunistic fungus Candida albicans and the key bacterial pathogen in periodontitis, Porphyromonas gingivalis. Both species use arsenals of virulence factors to invade the host organism and evade its immune system including peptidylarginine deiminase that citrullinates microbial and host proteins, altering their function. We assessed the effects of this modification on the interactions between the C. albicans cell surface and human plasminogen and kininogen, key components of plasma proteolytic cascades related to the maintenance of hemostasis and innate immunity. Mass spectrometry was used to identify protein citrullination, and microplate tests to quantify the binding of modified plasminogen and kininogen to C. albicans cells. Competitive radioreceptor assays tested the affinity of citrullinated kinins to their specific cellular receptors. The citrullination of surface-exposed fungal proteins reduced the level of unmodified plasminogen binding but did not affect unmodified kininogen binding. However, the modification of human proteins did not disrupt their adsorption to the unmodified fungal cells. In contrast, the citrullination of kinins exerted a significant impact on their interactions with cellular receptors reducing their affinity and thus affecting the role of kinin peptides in the development of inflammation.

RevDate: 2020-04-08

Ramos LS, Mello TP, Branquinha MH, et al (2020)

Biofilm Formed by Candida haemulonii Species Complex: Structural Analysis and Extracellular Matrix Composition.

Journal of fungi (Basel, Switzerland), 6(2): pii:jof6020046.

Candida haemulonii species complex (C. haemulonii, C. duobushaemulonii, and C. haemulonii var. vulnera) has emerged as opportunistic, multidrug-resistant yeasts able to cause fungemia. Previously, we showed that C. haemulonii complex formed biofilm on polystyrene. Biofilm is a well-known virulence attribute of Candida spp. directly associated with drug resistance. In the present study, the architecture and the main extracellular matrix (ECM) components forming the biofilm over polystyrene were investigated in clinical isolates of the C. haemulonii complex. We also evaluated the ability of these fungi to form biofilm on catheters used in medical arena. The results revealed that all fungi formed biofilms on polystyrene after 48 h at 37 °C. Microscopic analyses demonstrated a dense network of yeasts forming the biofilm structure, with water channels and ECM. Regarding ECM, proteins and carbohydrates were the main components, followed by nucleic acids and sterols. Mature biofilms were also detected on late bladder (siliconized latex), nasoenteric (polyurethane), and nasogastric (polyvinyl chloride) catheters, with the biomasses being significantly greater than on polystyrene. Collectively, our results demonstrated the ability of the C. haemulonii species complex to form biofilm on different types of inert surfaces, which is an incontestable virulence attribute associated with devices-related candidemia in hospitalized individuals.

RevDate: 2020-04-07

Li X, Wu B, Chen H, et al (2018)

Recent developments in smart antibacterial surfaces to inhibit biofilm formation and bacterial infections.

Journal of materials chemistry. B, 6(26):4274-4292.

Since their development over 70 years, antibiotics are still the most effective strategy to treat bacterial biofilms and infections. However, the overuse of antibiotics in human healthcare and industrial applications has resulted in the development of serious antibiotic-resistant bacteria. Therefore, alternative ways to prevent bacteria attachment and biofilm formation are urgently needed. Recently, mediated biofilm formation processes and smart antibacterial surfaces have emerged as promising strategies to prevent and treat bacterial infections. This review discusses the recent progress in biofilm interference and smart antibacterial surfaces. Smart antibacterial and anti-biofilm surfaces should be responsive to the bacterial infection environment, switchable between various antibacterial functions and have a special bio-inspired structure and function. The major topics discussed are: (i) smart anti-biofilm surfaces via the prevention of biofilm formation or promoting mature biofilm dissolution, (ii) smart materials for reversible killing and/or release of bacteria, (iii) smart surfaces responsive to bacterial infection microenvironments or external stimuli and (iv) bio-inspired surfaces with antifouling and bactericidal properties.

RevDate: 2020-04-07

Zhou Z, Hu F, Hu S, et al (2018)

pH-Activated nanoparticles with targeting for the treatment of oral plaque biofilm.

Journal of materials chemistry. B, 6(4):586-592.

Oral plaque biofilms are highly resilient microbial assemblies that are challenging to eradicate. Herein, we describe the synthesis and study of pH-positive, doxycycline (DOX)-loaded nanocarriers to combat pathogenic biofilms. The mixed shell-core nanoparticles consisted of quaternary ammonium chitosan (TMC) as a positively charged section, which targeted nanoparticles to negatively charged biofilm surfaces. In addition liposomes were used as a DOX loading tool to eradicate the multidrug-resistant biofilm. In a drug release test, DOX release was pH-dependent with t1/2 = 0.75 h and 2.3 h for release at pH 4.5 and 6.8, respectively. Furthermore, TMC-Lip-DOX NPs could adhere to the biofilm and efficiently remove the biofilm from the hydroxyapatite (HA) surface. Furthermore, TMC-Lip-DOX NPs had biocomaptible properties and were non-toxic to MC3T3-E1 cells. This constitutes a highly effective pathway to control oral plaque biofilms and has a good potential use for dental biofilm therapies.

RevDate: 2020-04-07

Bing W, Sun H, Wang F, et al (2018)

Hydrogen-producing hyperthermophilic bacteria synthesized size-controllable fine gold nanoparticles with excellence for eradicating biofilm and antibacterial applications.

Journal of materials chemistry. B, 6(28):4602-4609.

Herein, we employed the hydrogen-producing hyperthermophilic bacterial strain Caldicellulosiruptor changbaiensis for preparing uniform and size-tunable gold nanoparticles (AuNPs). Compared with the commonly used chemically synthesized nanoparticles, the biological synthesis of nanoparticles appears to be a suitable process since it has a low manufacturing cost of scalability, good biocompatibility, and better nanoparticles stabilization. The produced AuNPs possessed a unique property, whereby the smallest AuNPs exhibited the highest peroxidase activity over a broad pH range, even at neutral pH, which was quite different from the commonly chemical-synthesized ones. Also, when the size of AuNPs increased, the peroxidase activity of B-AuNPs at neutral pH decreased. Owing to the excellent antibacterial capability of ROS, the AuNPs exhibited striking antibacterial properties against both Gram-positive and Gram-negative bacteria, and moreover, the AuNPs showed excellent ability to disperse bacterial biofilms both in vitro and in vivo. Our studies indicate that living bacterial cells, as a biosynthesizer, can synthesize size-controllable AuNPs with improved bioactivity. This work may promote the design and synthesis of other types of metal nanoparticles with defined properties for future applications.

RevDate: 2020-04-07

Wen J, Yeh CK, Y Sun (2018)

Salivary polypeptide/hyaluronic acid multilayer coatings act as "fungal repellents" and prevent biofilm formation on biomaterials.

Journal of materials chemistry. B, 6(10):1452-1457.

Candida-associated denture stomatitis (CADS) is a common, recurring clinical complication in denture wearers that can lead to serious oral and systemic health problems. Current management strategies are not satisfactory due to their short-acting and ineffective therapeutic effects. Here, we describe a new fungal biofilm controlling strategy using the polyelectrolyte layer-by-layer (LBL) self-assembly technology on denture materials. Conventional poly(methyl methacrylate) (PMMA) denture material discs were functionalized with negatively charged poly(methacrylic acid) (PMAA) via plasma-initiated surface grafting, followed by repetitive alternating coating with the salivary antimicrobial polypeptide histatin 5 (H-5; cationic polymer) and hyaluronic acid (HA; anionic polymer). On the other hand, the H-5/HA LBL coatings (i.e., the outermost layer was H-5) inhibited fungal attachment/adhesion, significantly reduced fungal biofilm formation, and showed synergistic effects with the antifungal drug miconazole. LBL surface hydrophilicity was not the key mechanism in controlling Candida biofilm formation. The current approach demonstrates the utility of a new design principle for fabricating anticandidal denture materials, as well as potentially other related medical devices, for controlling fungal biofilm formation and combating insidious infections.

RevDate: 2020-04-07

Liu G, Zhang Y, Liu X, et al (2020)

360-Degrees Distribution of Biofilm Quantity and Community in an Operational Unchlorinated Drinking Water Distribution Pipe.

Environmental science & technology [Epub ahead of print].

In the present study, triplicate rings of 360-degrees pipe surface of an operational drinking water distribution pipe were swabbed. Each ring was equally divided into 16 parts for swabbing. The collected swabs were grouped into 3 sections and compared with the biofilm samples sampled by sonication of specimens from the same pipe. The results showed that biofilm is unevenly distributed over the 16 parts and the 3 sections of the pipe surface. Both the active biomass and the number of observed OTUs increased as the measurements proceeded from the top to the bottom of the pipe. The bacterial community was dominated in all sections by Proteobacteria. At the genus level, Nitrospira spp., Terrimonas spp. and Hyphomicrobium spp. were dominant in all sections. Gaiella spp. and Vicinamibacter spp. dominated in S-I, Blastopirellula spp. and Pirellula spp. dominated in S-II, while Holophaga spp. and Phaeodactylibacter spp. dominated in S-III. When swabbing and pipe specimen sonication were compared, the results showed that the sampling strategy significantly influences the obtained biofilm bacterial community. A consistent multi-sectional swabbing strategy is proposed for future biofilm sampling; it involves collecting swabs from all sections and comparing the swabs from the same position/section across locations.

RevDate: 2020-04-07

Contreras-Guerrero P, Ortiz-Magdaleno M, Urcuyo-Alvarado MS, et al (2020)

Effect of dental restorative materials surface roughness on the in vitro biofilm formation of Streptococcus mutans biofilm.

American journal of dentistry, 33(2):59-63.

PURPOSE: To evaluate Streptococcus mutans biofilm formation over different restorative dental materials.

METHODS: Using a bioreactor over 72 hours, four commercially available ceramics were evaluated: IPS E-max Press, IPS E-max CAD, Lava Ultimate CAD-CAM, Vita Enamic and two resin composites (SR Nexco Paste and Brilliant NG). The results were evaluated using atomic force microscopy and confocal microscopy, the biofilm was stained and the arbitrary fluorescence units (AFU) quantified.

RESULTS: The results showed that IPS E-max CAD had the lowest roughness values (4.29±1.79 nm), while the highest values were observed for Vita Enamic discs ((77.13±17.35 nm). Analysis of S. mutans biofilm formation by AFU revealed lower values for IPS E-max CAD (6.77±1.67 nm); the highest values were found for Lava Ultimate (79.99±22.23 nm). Regarding the composite groups, SR Nexco Paste showed roughness values of 15.07±2.77 nm and lower arbitrary fluorescence units of 30.92±12.01 nm than Brilliant NT. There was a correlation between the surface roughness of ceramics and composite with S. mutans biofilm formation.

CLINICAL SIGNIFICANCE: The adhesion of oral bacteria to restorative dental materials plays a key role in the success of dental treatment; the surface roughness influences the S. mutans biofilm formation.

RevDate: 2020-04-07

Ishizawa M, Tomiyama K, Hasegawa H, et al (2020)

Comprehensive analysis of bacterial flora of a biofilm model in initial caries-inducing environment.

American journal of dentistry, 33(2):55-58.

PURPOSE: To analyze changes in pH and bacterial flora with duration of culture and timing of sugar supply using a polymicrobial biofilm model.

METHODS: The biofilm was prepared using the method of Exterkate et al. Stimulated saliva from an adult was collected on a glass slide and added to unbuffered McBain medium containing 0.2% sucrose and cultivated under anaerobic conditions for 10 hours. Cultivation continued anaerobically in saliva-free medium refreshed twice daily, with or without sucrose, in five groups: in the Control and Groups A and C, with 0.2% sucrose for 96, 192 and 288 hours, respectively; in Groups B and E, with 0.2% sucrose for 96 hours then, respectively, without for 96 and 192 hours; in Group D, with 0.2% sucrose for 96 hours, without for 96 hours, then with for 96 hours. The pH of all spent medium was measured. Total bacteria counts were determined by Q-PCR. The bacterial composition was determined by next-generation sequencing of 16S rDNA.

RESULTS: The pH of spent medium depended on the presence or absence of sucrose. Total bacteria counts were higher in A, C and D than the other groups, and markedly lower in Group E. Principal components analysis and cluster analysis showed wider variation of bacterial flora of the biofilm in Groups B, D and E than other groups.

CLINICAL SIGNIFICANCE: Inspection of bacterial flora of a biofilm model of the initial caries-inducing environment may lead to the development of materials and procedures for the prevention of dental caries.

RevDate: 2020-04-07

Li W, Xue M, Yu L, et al (2020)

QseBC is involved in the biofilm formation and antibiotic resistance in Escherichia coli isolated from bovine mastitis.

PeerJ, 8:e8833 pii:8833.

Background: Mastitis is one of the most common infectious diseases in dairy cattle and causes significant financial losses in the dairy industry worldwide. Antibiotic therapy has been used as the most effective strategy for clinical mastitis treatment. However, due to the extensive use of antibacterial agents, antimicrobial resistance (AMR) is considered to be one of the reasons for low cure rates in bovine mastitis. In addition, biofilms could protect bacteria by restricting antibiotic access and shielding the bacterial pathogen from mammary gland immune defences. The functional mechanisms of quorum sensing E. coli regulators B an d C (QseBC) have been well studied in E. coli model strains; however, whether QseBC regulates antibiotic susceptibility and biofilm formation in clinical E. coli strain has not been reported.

Methods: In this study, we performed construction of the qseBC gene mutant, complementation of the qseBC mutant, antimicrobial susceptibility testing, antibacterial activity assays, biofilm formation assays, real-time reverse transcription PCR (RT-PCR) experiments and electrophoretic mobility shift assays (EMSAs) to investigate the role of qseBC in regulating biofilm formation and antibiotic susceptibility in the clinical E. coli strain ECDCM2.

Results: We reported that inactivation of QseBC led to a decrease in biofilm formation capacity and an increase in antibiotic susceptibility of an E. coli strain isolated from a dairy cow that suffered from mastitis. In addition, this study indicated that QseBC increased biofilm formation by upregulating the transcription of the biofilm-associated genes bcsA, csgA, fliC, motA, wcaF and fimA and decreased antibiotic susceptibility by upregulating the transcription of the efflux-pump-associated genes marA, acrA, acrB, acrD, emrD and mdtH. We also performed EMSA assays, and the results showed that QseB can directly bind to the marA promoter.

Conclusions: The QseBC two-component system affects antibiotic sensitivity by regulating the transcription of efflux-pump-associated genes. Further, biofilm-formation-associated genes were also regulated by QseBC TCS in E. coli ECDCM2. Hence, this study might provide new clues to the prevention and treatment of infections caused by the clinical E. coli strains.

RevDate: 2020-04-07

Khoury ZH, Vila T, Puthran TR, et al (2020)

The Role of Candida albicans Secreted Polysaccharides in Augmenting Streptococcus mutans Adherence and Mixed Biofilm Formation: In vitro and in vivo Studies.

Frontiers in microbiology, 11:307.

The oral cavity is a complex environment harboring diverse microbial species that often co-exist within biofilms formed on oral surfaces. Within a biofilm, inter-species interactions can be synergistic in that the presence of one organism generates a niche for another enhancing colonization. Among these species are the opportunistic fungal pathogen Candida albicans and the bacterial species Streptococcus mutans, the etiologic agents of oral candidiasis and dental caries, respectively. Recent studies have reported enhanced prevalence of C. albicans in children with caries indicating potential clinical implications for this fungal-bacterial interaction. In this study, we aimed to specifically elucidate the role of C. albicans-derived polysaccharide biofilm matrix components in augmenting S. mutans colonization and mixed biofilm formation. Comparative evaluations of single and mixed species biofilms demonstrated significantly enhanced S. mutans retention in mixed biofilms with C. albicans. Further, S. mutans single species biofilms were enhanced upon exogenous supplementation with purified matrix material derived from C. albicans biofilms. Similarly, growth in C. albicans cell-free spent biofilm culture media enhanced S. mutans single species biofilm formation, however, the observed increase in S. mutans biofilms was significantly affected upon enzymatic digestion of polysaccharides in spent media, identifying C. albicans secreted polysaccharides as a key factor in mediating mixed biofilm formation. The enhanced S. mutans biofilms mediated by the various C. albicans effectors was also demonstrated using confocal laser scanning microscopy. Importantly, a clinically relevant mouse model of oral co-infection was adapted to demonstrate the C. albicans-mediated enhanced S. mutans colonization in a host. Analyses of harvested tissue and scanning electron microscopy demonstrated significantly higher S. mutans retention on teeth and tongues of co-infected mice compared to mice infected only with S. mutans. Collectively, the findings from this study strongly indicate that the secretion of polysacharides from C. albicans in the oral environment may impact the development of S. mutans biofilms, ultimately increasing dental caries and, therefore, Candida oral colonization should be considered as a factor in evaluating the risk of caries.

RevDate: 2020-04-07

Abdulhaq N, Nawaz Z, Zahoor MA, et al (2020)

Association of biofilm formation with multi drug resistance in clinical isolates of Pseudomonas aeruginosa.

EXCLI journal, 19:201-208 pii:Doc201.

Pseudomonas aeruginosa is considered as foremost cause of hospital acquired infections due to its innate and plasmid mediated resistance to multiple antibiotics making it a multi drug resistant (MDR) pathogen. Biofilm formation is a pathogenic mechanism harbored by this pathogen which further elevates its resistance to antibiotics and host defense system. The aim of the present study was to evaluate the biofilm forming potential and distribution of pslA gene in multi drug resistant Pseudomonas aeruginosa isolates obtained from different clinical samples. A total of 200 different clinical samples were collected after obtaining written consent from the patients. The samples were subjected to isolation and identification of P. aeruginosa by standard microbiological procedures. Confirmation of isolates was done by polymerase chain reaction targeting oprL gene. Kirby Bauer method was performed for detection of MDR isolates. Congo red agar (CRA) test and Microtiter plate assay (MPA) for observing the biofilm forming ability and amplification of pslA gene was also performed on MDR isolates. The results showed that from 200 samples 52 (26 %) were P. aeruginosa and among them 20 (38.46 %) were MDR isolates. The CRA showed 23 (44.23 %) while MPA detected 49 (94.23 %) isolates as biofilm producers while all the MDR isolates showed biofilm formation by MPA method. The pslA gene was detected in all biofilm forming isolates while 90 % in MDR P. aeruginosa. It was concluded that biofilm forming P. aeruginosa are more resistant to tested antibiotics and biofilm formation is strongly associated with presence of pslA gene.

RevDate: 2020-04-07

Al-Shabib NA, Husain FM, Rehman MT, et al (2020)

Food color 'Azorubine' interferes with quorum sensing regulated functions and obliterates biofilm formed by food associated bacteria: An in vitro and in silico approach.

Saudi journal of biological sciences, 27(4):1080-1090.

Quorum sensing (QS) plays a crucial role in different stages of biofilm development, virulence production, and subsequently to the growth of bacteria in food environments. Biofilm mediated spoilage of food is one of the ongoing challenge faced by the food industry worldwide as it incurs substantial economic losses and leads to various health issues. In the present investigation, we studied the interference of quorum sensing, its regulated virulence functions, and biofilm in food-associated bacteria by colorant azorubine. In vitro bioassays demonstrated significant inhibition of QS and its coordinated virulence functions in Chromobacterium violaceum 12472 (violacein) and Pseudomonas aeruginosa PAO1 (elastase, protease, pyocyanin, and alginate). Further, the decrease in the production EPS (49-63%) and swarming motility (61-83%) of the pathogens was also recorded at sub-MICs. Azorubine demonstrated broad-spectrum biofilm inhibitory potency (50-65%) against Chromobacterium violaceum, Pseudomonas aeruginosa, E. coli O157:H7, Serratia marcescens, and Listeria monocytogenes. ROS generation due to the interaction between bacteria and azorubine could be responsible for the biofilm inhibitory action of the food colorant. Findings of the in vitro studies were well supported by molecular docking and simulation analysis of azorubine and QS virulence proteins. Azorubine showed strong binding to PqsA as compared to other virulent proteins (LasR, Vfr, and QscR). Thus, it is concluded that azorubine is a promising candidate to ensure food safety by curbing the menace of bacterial QS and biofilm-based spoilage of food and reduce economic losses.

RevDate: 2020-04-07

Arias SL, Devorkin J, Civantos A, et al (2020)

E. coli adhesion and biofilm formation on polydimethylsiloxane are independent of substrate stiffness.

Langmuir : the ACS journal of surfaces and colloids [Epub ahead of print].

Bacterial adhesion and biofilm formation on the surface of biomedical devices is a detrimental process that compromises patient safety and material functionality. Several physicochemical factors are involved in biofilm growth, including the surface properties. Among those, material stiffness has recently been suggested to influence microbial adhesion and biofilm growth in a variety of polymers and hydrogels. However, no clear consensus exists about the role of material stiffness on biofilm initiation and whether very compliant substrates are deleterious to bacterial cell adhesion. Here, by systematically tuning substrate topography and stiffness while keeping the surface free energy of polydimethylsiloxane substrates constant, we show that topographical patterns at the micron and submicron scale impart unique properties to the surface that are independent of the material stiffness. The current work provides a better understanding of the role of material stiffness on bacterial physiology and may constitute a cost-effective and simple strategy to reduce bacterial attachment and biofilm growth even in very compliant and hydrophobic polymers.

RevDate: 2020-04-07

Flannery A, Le Berre M, Pier GB, et al (2020)

Glycomics Microarrays Reveal Differential In Situ Presentation of the Biofilm Polysaccharide Poly-N-acetylglucosamine on Acinetobacter baumannii and Staphylococcus aureus Cell Surfaces.

International journal of molecular sciences, 21(7): pii:ijms21072465.

The biofilm component poly-N-acetylglucosamine (PNAG) is an important virulence determinant in medical-device-related infections caused by ESKAPE group pathogens including Gram-positive Staphylococcus aureus and Gram-negative Acinetobacter baumannii. PNAG presentation on bacterial cell surfaces and its accessibility for host interactions are not fully understood. We employed a lectin microarray to examine PNAG surface presentation and interactions on methicillin-sensitive (MSSA) and methicillin-resistant S. aureus (MRSA) and a clinical A. baumannii isolate. Purified PNAG bound to wheatgerm agglutinin (WGA) and succinylated WGA (sWGA) lectins only. PNAG was the main accessible surface component on MSSA but was relatively inaccessible on the A. baumannii surface, where it modulated the presentation of other surface molecules. Carbohydrate microarrays demonstrated similar specificities of S. aureus and A. baumannii for their most intensely binding carbohydrates, including 3' and 6'sialyllactose, but differences in moderately binding ligands, including blood groups A and B. An N-acetylglucosamine-binding lectin function which binds to PNAG identified on the A. baumannii cell surface may contribute to biofilm structure and PNAG surface presentation on A. baumannii. Overall, these data indicated differences in PNAG presentation and accessibility for interactions on Gram-positive and Gram-negative cell surfaces which may play an important role in biofilm-mediated pathogenesis.

RevDate: 2020-04-07

Bissong MEA, CN Ateba (2020)

Genotypic and Phenotypic Evaluation of Biofilm Production and Antimicrobial Resistance in Staphylococcus aureus Isolated from Milk, North West Province, South Africa.

Antibiotics (Basel, Switzerland), 9(4): pii:antibiotics9040156.

Background: Biofilm formation in S. aureus may reduce the rate of penetration of antibiotics, thereby complicating treatment of infections caused by these bacteria. The aim of this study was to correlate biofilm-forming potentials, antimicrobial resistance, and genes in S. aureus isolates. Methods: A total of 64 milk samples were analysed, and 77 S. aureus were isolated. Results: Seventy (90.9%) isolates were biofilm producers. The ica biofilm-forming genes were detected among 75.3% of the isolates, with icaA being the most prevalent (49, 63.6%). The icaB gene was significantly (P = 0.027) higher in isolates with strong biofilm formation potentials. High resistance (60%-90%) of the isolates was observed against ceftriaxone, vancomycin, and penicillin, and 25 (32.5%) of S. aureus showed multidrug resistance (MDR) to at least three antibiotics. Five resistance genes, namely blaZ (29, 37.7%), vanC (29, 37.7%), tetK (24, 31.2%), tetL (21, 27.3%), and msrA/B (16, 20.8%) were detected. Most MDR phenotypes possessed at least one resistance gene alongside the biofilm genes. However, no distinct pattern was identified among the resistance and biofilm phenotypes. Conclusions: The high frequency of potentially pathogenic MDR S. aureus in milk samples intended for human consumption, demonstrates the public health relevance of this pathogen in the region.

RevDate: 2020-04-06

Feng X, Wu Q, Che L, et al (2020)

Analyzing the inhibitory effect of metabolic uncoupler on bacterial initial attachment and biofilm development and the underlying mechanism.

Environmental research, 185:109390 pii:S0013-9351(20)30283-8 [Epub ahead of print].

Metabolic uncouplers inhibit biofilm and biofouling formation in membrane bioreactor (MBR) systems, which have been considered as a potential biofouling control alternative. To better understand the inhibitory mechanism of uncoupler on biofouling, this study investigated the impact of the uncoupler 3, 3', 4', 5-tetrachlorosalicylanilide (TCS) on biofilm formation of B. subtilis in different development stages. Significant reductions in both the initial bacterial attachment stage and the subsequent biofilm development stage were caused by TCS at 100 μg/L. The motility of B. subtilis in semisolid medium was inhibited by TCS, which explicitly explained the reduction in initial bacterial attachment. Meanwhile, a reduction of extracellular polymeric substance (EPS) secretion owing to TCS suggested why biofilm development was suppressed. In addition, the fluorescent materials in tight-bound EPS (TB-EPS) and loose-bound EPS (LB-EPS) of Bacillus subtilis cultured in different TCS concentrations were distinguished and quantified by three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC). The results of this study suggested that the biofilm inhibitory mechanism of the uncoupler was both a inhibition in bacterial motor ability and a reduction in EPS secretion.

RevDate: 2020-04-06

Wang J, Li G, Yin H, et al (2020)

Bacterial response mechanism during biofilm growth on different metal material substrates: EPS characteristics, oxidative stress and molecular regulatory network analysis.

Environmental research, 185:109451 pii:S0013-9351(20)30344-3 [Epub ahead of print].

Overwhelming growth of bacterial biofilms on different metal-based pipeline materials are intractable and pose a serious threat to public health when tap water flows though these pipelines. Indeed, the underlying mechanism of biofilm growth on the surface of different pipeline materials deserves detailed exploration to provide subsequent implementation strategies for biofilm control. Thus, in this study, how bacteria response to their encounters was explored, when they inhabit different metal-based pipeline substrates. Results revealed that bacteria proliferated when they grew on stainless steel (SS) and titanium sheet (Ti), quickly developing into bacterial biofilms. In contrast, the abundance of bacteria on copper (Cu) and nickel foam (Ni) substates decreased sharply by 4-5 logs within 24 h. The morphological shrinkage and shortening of bacterial cells, as well as a sudden 64-fold increase of carbohydrate content in extracellular polymeric substances (EPS), were observed on Cu substrate. Furthermore, generation of reactive oxygen species and fluctuation of enzymatic activity demonstrated the destruction of redox equilibrium in bacteria. Bacteria cultured on Cu substrate showed the strongest response, followed by Ni, SS and Ti. The oxidative stress increased quickly during the growth of bacterial biofilm, and almost all tested metal transporter-related genes were upregulated by 2-11 folds on Cu, which were higher than on other substrates (1-2 folds for SS and Ti, 2-9 folds for Ni). Finally, these behaviors were compared under the biofilm regulatory molecular network. This work may facilitate better understanding different response mechanisms during bacterial biofilm colonization on metal-based pipelines and provide implications for subsequent biofilm control.

RevDate: 2020-04-06

Lee JH, Kim YG, Khadke SK, et al (2020)

Correction to Inhibition of Biofilm Formation by Candida albicans and Polymicrobial Microorganisms by Nepodin via Hyphal-Growth Suppression.

RevDate: 2020-04-06

Tsuchiya Y, Nakagawa T, R Takahashi (2020)

Quantification and Phylogenetic Analysis of Ammonia Oxidizers on Biofilm Carriers in a Full-Scale Wastewater Treatment Plant.

Microbes and environments, 35(2):.

Biofilm carriers have been used to remove ammonia in several wastewater treatment plants (WWTPs) in Japan. However, the abundance and species of ammonia oxidizers in the biofilms formed on the surface of carriers in full-scale operational WWTP tanks remain unclear. In the present study, we conducted quantitative PCR and PCR cloning of the amoA genes of ammonia-oxidizing bacteria and archaea (AOB and AOA) and a complete ammonia oxidizer (comammox) in the biofilm formed on the carriers in a full-scale WWTP. The quantification of amoA genes showed that the abundance of AOB and comammox was markedly greater in the biofilm than in the activated sludge suspended in a tank solution of the WWTP, while AOA was not detected in the biofilm or the activated sludge. A phylogenetic analysis of amoA genes revealed that as-yet-uncultivated comammox Nitrospira and uncultured AOB Nitrosomonas were predominant in the biofilm. The present results suggest that the biofilm formed on the surface of carriers enable comammox Nitrospira and AOB Nitrosomonas to co-exist and remain in the full-scale WWTP tank surveyed in this study.

RevDate: 2020-04-06

Kishii K, Hamada M, Aoki K, et al (2020)

Differences in biofilm formation and transcription of biofilm-associated genes among Acinetobacter baumannii clinical strains belonging to the international clone II lineage.

Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy pii:S1341-321X(20)30067-2 [Epub ahead of print].

Acinetobacter baumannii isolates belonging to international clonal lineage (IC) II are often multidrug-resistant and are the predominant cause of nosocomial outbreaks. While many studies have investigated the genetic and functional basis of antimicrobial resistance of these strains, few have examined specific virulence characteristics such as biofilm formation or overall pathogenic potential. Here, we analyzed biofilm formation and the associated mechanisms in A. baumannii clinical isolates from Japan belonging to the IC II lineage. Draft whole-genome sequence data for each of the isolates was analyzed to detect biofilm-associated genes, including csu (pili) and bfmS/R (two-component regulatory system), and transcription of these genes was evaluated using reverse transcription quantitative PCR. Biofilm formation was measured by crystal violet staining assay. csu operon genes showed some variation in prevalence among the isolates, with an overall prevalence of 73.7% (14/19). The biofilms formed by csu operon-positive isolates were significantly more mature than those of csu operon-negative isolates, supporting the importance of the csu operon in biofilm formation by A. baumannii. However, there was substantial variation among the csu operon-positive isolates, indicating the influence of other factors in biofilm formation. Furthermore, transcriptional levels of csu operon genes were highly divergent, with comprehensive analysis indicating that regulatory factors other than bfmS/R were involved. Our findings are a first step towards understanding the mechanisms of biofilm formation by A. baumannii IC II strains.

RevDate: 2020-04-05

Duc HM, Son HM, Ngan PH, et al (2020)

Isolation and application of bacteriophages alone or in combination with nisin against planktonic and biofilm cells of Staphylococcus aureus.

Applied microbiology and biotechnology pii:10.1007/s00253-020-10581-4 [Epub ahead of print].

Staphylococcus aureus is a notorious foodborne pathogen since it has ability to produce variety of toxins including heat-stable enterotoxin, form biofilm, and acquire resistance to antibiotics. Biocontrol of foodborne pathogens by lytic bacteriophages garners increasing interest from both researchers and food industry. In the present study, 29 phages against S. aureus were successfully isolated from chicken, pork, and fish. Characterization of the isolates revealed that phage SA46-CTH2 belonging to Podoviridae family had a number of features suitable for food industry applications such as wide host range, short latent period, large burst size, high stress tolerance, and a genome free of virulence genes. Furthermore, phage SA46-CTH2 alone or in combination with nisin exhibited great efficacy in reducing planktonic and biofilm cells of S. aureus at various conditions tested. The combination of phage SA46-CTH2 and nisin was also found to be able to inhibit the regrowth of S. aureus at both 37 and 24 °C.Key points • A total of 29 S. aureus phages were successfully isolated from fish, pork, and chicken products. • Phage SA46-CTH2 was characterized by host range, morphology, and genome sequencing. • SA46-CTH2 significantly reduced both planktonic and biofilm cells of S. aureus. • Combination of SA46-CTH2 and nisin inhibited the regrowth of S. aureus.

RevDate: 2020-04-05

Shu Q, Wei T, Lu H, et al (2020)

Mannosylerythritol lipids: dual inhibitory modes against Staphylococcus aureus through membrane-mediated apoptosis and biofilm disruption.

Applied microbiology and biotechnology pii:10.1007/s00253-020-10561-8 [Epub ahead of print].

Mannosylerythritol lipids (MELs) are novel biosurfactants performing excellent physical-chemical properties as well as bioactivities. This study is aimed to explore the antibacterial and antibiofilm activity of mannosylerythritol lipids against foodborne gram-positive Staphylococcus aureus. The results of growth curve and survival rate revealed the significant inhibitory effect of MELs against S. aureus. The visualized pictures by scanning electron microscope and transmission electron microscope exposed apparent morphological and ultrastructure changes of MEL-treated cells. Furthermore, flow cytometry confirmed that MELs have promoted cell apoptosis and damaged the cell membrane. Notably, MEL-A also exhibited outstanding antibiofilm activity against S. aureus biofilm on different material surfaces including polystyrene, glass, and stainless steel, verified by confocal laser scanning microscope. These findings suggest that the antimicrobial activity of MELs is related to inhibit planktonic cells and biofilm of S. aureus, indicating that it has potential to be an alternative to antibacterial agents and preservatives applied into food processing.Key Points • MELs have strong antibacterial activity against Staphylococcus aureus.• MELs mainly damage the cell membrane of Staphylococcus aureus.• Mannosylerythritol lipids inhibit the bacterial adhesion to remove biofilm.

RevDate: 2020-04-04

Narayanan VS, Muddaiah S, Shashidara R, et al (2020)

Variable antifungal activity of curcumin against planktonic and biofilm phase of different candida species.

Indian journal of dental research : official publication of Indian Society for Dental Research, 31(1):145-148.

Objective: To evaluate the in vitro antifungal activity of curcumin against 2 strains of Candida albicans (ATCC 90028 and a clinical isolate - JY strain) and 1 isolate each of 3 nonalbicans - Candida species [Candida parapsilosis (ATCC 22019), C. glabrata (ATCC 90030), and C. dublieniensis (MYA 646)].

Materials and Methods: Planktonic MIC of the 4 Candida species was determined using micro broth dilution assay according to CLSI M27-A3 criteria. The biofilm development and sensitivity assay were performed with the 2 C. albicans strains.

Results: Curcumin at high concentrations (0.1-2 mg/mL) was effective in inhibiting planktonic organisms of all the 5 tested Candida strains. The planktonic phase and the biofilm phase of C. albicans ATCC 90028 exhibited similar MIC values for curcumin (0.5 mg/mL). Both curcumin and fluconazole were ineffective against the mature biofilms of JY strain.

Conclusion: Our results reported here for the first time, in particular for the biofilm state of C. albicans, imply that curcumin a natural product could be used as a therapeutic alternative to conventional antifungals although further investigations are required to evaluate its potential.

RevDate: 2020-04-04

Romero F, Acuña V, S Sabater (2020)

Multiple stressors determine community structure and estimated function of river biofilm bacteria.

Applied and environmental microbiology pii:AEM.00291-20 [Epub ahead of print].

Freshwater ecosystems are exposed to multiple stressors, but their individual and combined effects remain largely unexplored. Here, we investigated the response of stream biofilm bacterial communities to warming, hydrological stress and pesticide exposure. We used 24 artificial streams onto which epilithic (growing on coarse sediments) and epipsammic (growing on fine sediments) stream biofilms were maintained. Bacterial community composition and estimated function of biofilms exposed during 30 days to individual and combined stressors were assessed using 16S rRNA gene metabarcoding. Among the individual effects by stressors, hydrological stress (i.e. a simulated low-flow situation) was the most relevant, as it significantly altered 57% of the most abundant bacterial taxa (n = 28), followed by warming (21%) and pesticide exposure (11%). Regarding the combined effects, 16% of all stressor combinations resulted in significant interactions on bacterial community composition and estimated function. Antagonistic responses prevailed (57-89% of all significant interactions), followed by synergisms (11-43%), on specific bacterial taxa, indicating that multiple-stressor scenarios could lead to unexpected shifts in the community composition and associated functions of riverine bacterial communities.Importance paragraph Freshwater ecosystems such as rivers are of crucial importance for human well-being. However, human activities result in many stressors (e.g. toxic chemicals, increased water temperatures, and hydrological alterations) co-occurring in rivers and streams worldwide. Among the many organisms inhabiting rivers and streams, bacteria are ecologically crucial; they are placed at the base of virtually all food webs and they recycle the organic matter needed for bigger organisms. Most of these bacteria are in close contact with river substratum, where they form the biofilms. There is an urgent need to evaluate the effects of these stressors on river biofilms, so we can anticipate future environmental problems. In this study, we experimentally exposed river biofilms to a pesticide mixture, an increase in water temperature and a simulated low-flow condition, in order to evaluate the individual and joint effects of these stressors on the bacterial community composition and estimated function.

RevDate: 2020-04-03

Wen HQ, Ren HY, Xie GJ, et al (2020)

Synthesized effects of proteomic and extracellular polymeric substance (EPS) revealing the enhanced hydrogen production by formed biofilm of photo-fermentative bacteria.

Environment international, 139:105683 pii:S0160-4120(20)30273-7 [Epub ahead of print].

Photo-fermentative hydrogen production, the new energy production alternative, was greatly enhanced by formed biofilm. To understand the mechanism of enhancement, the intracellular proteome and extracellular polymeric substance (EPS)i during biofilm formation were investigated in this work. Experimental results indicated that a possible and effective altered system could transfer light to hydrogen. Proteins were significantly regulated, for example those related with nitrogenase, flagellin, EPS transportation and DNA duplication were up-regulated while those concerned photosystem were down-regulated. It revealed these changes of proteins contributed to positive activity of key enzymes, improved communication system and increased total light utilization efficiency thus leading to enhanced capacity of hydrogen production. Besides above metabolic changes inside the cells, EPS secreted by the bacteria played an important role in hydrogen production and its yield decided the release of hydrogen. When EPS descended to a lower concentration during biofilm formation, it meant carbon source for EPS synthesis was reduced, and more energy and reducing power could be transferred into hydrogen energy. More importantly, this work found that composition and structure of EPS were efficiently influenced by the formation of biofilm, such as benzene and O-H structure, secondary protein structure and the kinds of protein, which were important to stable biofilm and efficient hydrogen production. Therefore, final hydrogen yield was improved by altered protein and EPS resulted from biofilm formation. This study demonstrated that formation of biofilm is an efficient, ecological and attracting way to the future bio-hydrogen production.

RevDate: 2020-04-03

Ho DK, Murgia X, De Rossi C, et al (2020)

Squalenyl Hydrogen Sulfate Nanoparticles for Simultaneous Delivery of Tobramycin and Alkylquinolone Quorum Sensing Inhibitor to Eradicate P. aeruginosa Biofilm Infections.

Angewandte Chemie (International ed. in English) [Epub ahead of print].

Elimination of pulmonary Pseudomonas aeruginosa (PA) infections is challenging to accomplish with antibiotic therapies, mainly due to formidable resistance mechanisms. Quorum sensing inhibitors (QSIs) interfering with biofilm formation can thus complement antibiotics. For simultaneous and improved delivery of both actives to the infection sites, self-assembling nanoparticles of a newly synthesized Squalenyl Hydrogen Sulfate (called SqNPs) were prepared. These nanocarriers allowed for remarkably high loading capacities of both hydrophilic antibiotic Tobramycin (Tob) and novel lipophilic QSI at 30% and ~10%, respectively. The obtained drug-loaded SqNPs showed improved biofilm penetration and enhanced efficacy in relevant biological barriers (mucin/human tracheal mucus, biofilm), leading to complete eradication of PA biofilms at ~16-fold lower Tob concentration than Tob alone. This study offers a viable therapy optimization and invigorates the research and development of QSIs for clinical use.

RevDate: 2020-04-03

Alejandra GK, Ivonne CO, Sarahí LC, et al (2020)

Bovine lactoferrin can decrease the in vitro biofilm production or shown synergy with antibiotics against Listeria and Escherichia coli isolates.

BACKGROUND: Bovine lactoferrin (bLf) has been reported as antimicrobial, antiviral, immunomodulatory and anticancer protein. Escherichia coli and Listeria spp. are food-borne bacteria that can produce illness in human being and mammals, the emergent antimicrobial drug resistance has been reported in these pathogens.

OBJECTIVE: The aim for this study was to evaluate the bLf effect on in vitro biofilm production and the synergic effect of antibiotics on E. coli and Listeria isolates.

METHODS: E. coli and Listeria specimens were isolated from bovine carcasses and slaughterhouses surfaces, respectively. Biofilm formation was analyzed with or without bLf, incubated for 48 h and spectrophotometry, cell viability was analyzed by colony-forming unit (CFU) and the synergistic effect of bLf with ampicillin, oxytetracycline, and streptomycin was evaluated through the fractional concentration index (FCI).

RESULTS: Our results show that a low bLf concentration (0.8 μM) can diminish the in vitro biofilm production in Listeria isolates; also improves the in vitro oxytetracycline and streptomycin activity against E. coli, and ampicillin activity against Listeria isolates.

CONCLUSION: bLf can affect the biofilm production in Listeria isolates from slaughterhouses surfaces and shown synergic effect with ampicillin. Also has a synergic effect with oxytetracycline and streptomycin against E. coli isolates from bovine carcasses.

RevDate: 2020-04-03

Robino L, P Scavone (2020)

Nanotechnology in biofilm prevention.

RevDate: 2020-04-03

Angiolella L, Rojas F, Mussin J, et al (2020)

Biofilm formation, adherence, and hydrophobicity of M. sympodialis, M. globosa, and M. slooffiae from clinical isolates and normal skinVirulence factors of M. sympodialis, M. globosa and M. slooffiae.

Medical mycology pii:5815444 [Epub ahead of print].

The genus Malassezia comprises a heterogeneous group of species that cause similar pathologies. Malassezia yeasts were considered as the most abundant skin eukaryotes of the total skin mycobiome. The ability of this fungus to colonize or infect is determined by complex interactions between the fungal cell and its virulence factors. This study aims to evaluate in vitro the hydrophobicity levels, the adherence capacity on a polystyrene surface and the ability to form biofilm of 19 isolates, including M. sympodialis, M. globosa, and M. slooffiae, from healthy subjects and from dermatological disorders. Cellular surface hydrophobicity levels were determined by two-phase system. The biofilm formation was determined by tetrazolium salt (XTT) reduction assay and by Scanning Electron Microscopy (SEM). Strain dependence was observed in all virulence factors studied. All isolates of M. sympodialis, M. globosa, and M. slooffiae demonstrated their ability to form biofilm at variable capacities. SEM observations confirmed a variable extracellular matrix after 48 hours of biofilm formation. All isolates of M. globosa were highly adherent and/or hydrophobic as well as biofilm producers. In contrast, M. slooffiae was the least biofilm producer. No significant differences between virulence factors were demonstrated for M. sympodialis, either as clinical isolate or as inhabitant of human microbiota. Results of this work together with the previous M. furfur research confirm that the most frequently Malassezia species isolated from normal subject's skin and patients with dermatosis, form biofilm with different capacities. The study of these virulence factors is important to highlight differences between Malassezia species and to determine their involvement in pathological processes.

RevDate: 2020-04-03

Zhang L, Li Z, Z Chen (2020)

Live cell fluorescent stain of bacterial curli and biofilm through supramolecular recognition between bromophenol blue and CsgA.

Chemical communications (Cambridge, England) [Epub ahead of print].

Identification of curli-specific dyes for biofilm communities of microorganisms is an important task. We describe here a curli fluorescent light-up probe called bromophenol blue, which binds to curli via recognizing CsgA. This platform may provide a new perspective for the research on biofilm, amyloid disease and living materials.

RevDate: 2020-04-03

Starr CG, Ghimire J, Guha S, et al (2020)

Synthetic molecular evolution of host cell-compatible, antimicrobial peptides effective against drug-resistant, biofilm-forming bacteria.

Proceedings of the National Academy of Sciences of the United States of America pii:1918427117 [Epub ahead of print].

Novel classes of antibiotics and new strategies to prevent and treat infections are urgently needed because the rapid rise in drug-resistant bacterial infections in recent decades has been accompanied by a parallel decline in development of new antibiotics. Membrane permeabilizing antimicrobial peptides (AMPs) have long been considered a potentially promising, novel class of antibiotic, especially for wound protection and treatment to prevent the development of serious infections. Yet, despite thousands of known examples, AMPs have only infrequently proceeded as far as clinical trials, especially the chemically simple, linear examples. In part, this is due to impediments that often limit their applications in vivo. These can include low solubility, residual toxicity, susceptibility to proteolysis, and loss of activity due to host cell, tissue, and protein binding. Here we show how synthetic molecular evolution can be used to evolve potentially advantageous antimicrobial peptides that lack these impediments from parent peptides that have at least some of them. As an example of how the antibiotic discovery pipeline can be populated with more promising candidates, we evolved and optimized one family of linear AMPs into a new generation with high solubility, low cytotoxicity, potent broad-spectrum sterilizing activity against a panel of gram-positive and gram-negative ESKAPE pathogens, and antibiofilm activity against gram-positive and gram-negative biofilms. The evolved peptides have these activities in vitro even in the presence of concentrated host cells and also in vivo in the complex, cell- and protein-rich environment of a purulent animal wound model infected with drug-resistant bacteria.

RevDate: 2020-04-02

Ayoub HM, Gregory RL, Tang Q, et al (2020)

Comparison of human and bovine enamel in a microbial caries model at different biofilm maturations.

Journal of dentistry pii:S0300-5712(20)30067-1 [Epub ahead of print].

OBJECTIVES: To compare human versus bovine enamel when used in microbial caries models; and to evaluate the use of nylon mesh to support biofilm growth over enamel.

METHODS: Twenty-four sub-subgroups were included (time factor: 4, 8, and 12 days; substrate factor: human/bovine; mesh factor: yes/no; treatment factor: 18.4 mM NaF (350 ppm F), de-ionized water [DIW]; n = 9/sub-subgroup). Microcosm biofilm from human saliva (IRB approval #1,406,440,799) was grown on enamel specimens for 24-h (Brain Heart Infusion media; 0.2 % sucrose), using active attachment model. Then, pH-cycling took place. At the end of each pH-cycling period, enamel specimens were analyzed: surface microhardness (VHNchange); transverse microradiography (integrated mineral loss [ΔZ], lesion depth [L]). Biofilm was analyzed: lactic acid production (LDH activity); exopolysaccharide (EPS) amount; and viability (12-day sub-groups). Data were analyzed using ANOVA at a 5 % level of significance.

RESULTS: The three-way interaction between pH-cycling duration, substrate type, and treatment type was significant for (VHNchange [p < 0.0005], ΔZ [p = 0.0027], and L [p < 0.0001]). VHNchange exhibited increased lesion severity as pH-cycling time increases, in both treatments. VHNchange data indicated a treatment effect in all timepoints. ΔZ and L exhibited higher values with more mature biofilms. ANOVA analyses for LDH and EPS indicated a significance between variables (LDH p = 0.0100; EPS p < 0.0001). Mesh-covered specimens resulted in lower LDH and EPS values in all maturations. ANOVA analyses of viability (12 days) between variables was significant.

CONCLUSION: within the study's limitations, human or bovine enamel can be used in microbial in vitro caries models to study biofilm's maturation and anticaries agents.

CLINICAL SIGNIFICANCE: This study demonstrated how a known cariostatic effect of a fluoride concentration in toothpastes can be modulated by the maturation stage of oral biofilm. This can represent hard to reach areas in the oral cavity (e.g. in orthodontic patients or patients with intermaxillary fixation following oral and maxillofacial surgeries).

RevDate: 2020-04-02

Ageorges V, Monteiro R, Leroy S, et al (2020)

Molecular Determinants of Surface Colonisation in Diarrhoeagenic Escherichia coli (DEC): from Bacterial Adhesion to Biofilm Formation.

FEMS microbiology reviews pii:5815079 [Epub ahead of print].

Escherichia coli is primarily known as a commensal colonising the gastrointestinal tract of infants very early in life but some strains being responsible for diarrhoea, which can be especially severe in young children. Intestinal pathogenic E. coli include six pathotypes of diarrhoeagenic E. coli (DEC), namely the (i) enterotoxigenic E. coli, (ii) enteroaggregative E. coli, (iii) enteropathogenic E. coli, (iv) enterohemorragic E. coli, (v) enteroinvasive E. coli, and (vi) diffusely-adherent E. coli. Prior to human infection, DEC can be found in natural environments, animal reservoirs, food processing environments and contaminated food matrices. From an ecophysiological point of view, DEC thus deal with very different biotopes and biocoenoses all along the food chain. In this context, this review focuses on the wide range of surface molecular determinants acting as surface colonisation factors (SCFs) in DEC. In the first instance, SCFs can be broadly discriminated into (i) extracellular polysaccharides, (ii) extracellular DNA, and (iii) surface proteins. Surface proteins constitute the most diverse group of SCFs broadly discriminated into (i) monomeric SCFs, such as autotransporter (AT) adhesins, inverted ATs, heat-resistant agglutinins or some moonlighting proteins, (ii) oligomeric SCFs, namely the trimeric ATs, and (iii) supramolecular SCFs, including flagella and numerous pili, e.g. the injectisome, type 4 pili, curli chaperone-usher pili or conjugative pili. This review also details the gene regulatory network of these numerous SCFs at the various stages as it occurs from pre-transcriptional to post-translocational levels, which remains to be fully elucidated in many cases.

RevDate: 2020-04-02

Macedo VC, Pereira PC, Queiroz JRC, et al (2020)

Effect of Air-Particle-Abrasion Protocols on Surface Roughness and Early Biofilm Formation of Zirconia.

Oral health & preventive dentistry, 18(2):153-159.

PURPOSE: The air-particle-abrasion on zirconia in the gingival area of connectors and pontics in fixed partial dentures appears to increase fracture resistance. This study evaluated 'in situ' biofilm formation on the zirconia surface after different air-particle-abrasion protocols.

MATERIALS AND METHODS: Ninety sintered blocks (5 × 5 × 2 mm) of yttrium partially stabilised zirconia (Y-TZP) were obtained and randomised among nine groups according to the factors 'type of particle' (Alumina 50 and 110 µm; Cojet and Rocatec) and 'pressure' (2.5 and 3.5 bar) used for sandblasting for 10 s. The surface roughness (Ra/Rz) was measured before and after sandblasting. For the in-situ analyses, custom-made removable intraoral devices n = 10 with one sample of each group attached to the buccal area were used by volunteers for 8 h at night. The specimens were analysed under confocal microscopy to quantify both biovolume and thickness of the initial biofilm formed. One-way analysis of variance (ANOVA) and Dunnett's tests were performed (5%).

RESULTS: The roughness values ranged from 0.05 to 0.39 µm for Ra and from 0.35 to 2.11 µm for Rz, p = 0.00. Mean biofilm thickness ranged from 0.06 and 0.54 µm (p = 0.005), while the biovolume values were between 0.02 and 0.61 µm3/µm2 (p = 0.002). Values statistically significant for biofilm thickness and biovolume were found in groups sandblasted with Rocatec using 3.5 bar.

CONCLUSION: In order to increase the fracture resistance of zirconia fixed partial dentures (FPDs), the air particle abrasion of zirconia with SiO2 (110 μm/3.5 bar), in the gingival area of connectors and pontics, should be avoided.

RevDate: 2020-04-02

Galdiero E, de Alteriis E, De Natale A, et al (2020)

Eradication of Candida albicans persister cell biofilm by the membranotropic peptide gH625.

Scientific reports, 10(1):5780 pii:10.1038/s41598-020-62746-w.

Biofilm formation poses an important clinical trouble due to resistance to antimicrobial agents; therefore, there is an urgent demand for new antibiofilm strategies that focus on the use of alternative compounds also in combination with conventional drugs. Drug-tolerant persisters are present in Candida albicans biofilms and are detected following treatment with high doses of amphotericin B. In this study, persisters were found in biofilms treated with amphotericin B of two clinical isolate strains, and were capable to form a new biofilm in situ. We investigated the possibility of eradicating persister-derived biofilms from these two Candida albicans strains, using the peptide gH625 analogue (gH625-M). Confocal microscopy studies allowed us to characterize the persister-derived biofilm and understand the mechanism of interaction of gH625-M with the biofilm. These findings confirm that persisters may be responsible for Candida biofilm survival, and prove that gH625-M was very effective in eradicating persister-derived biofilms both alone and in combination with conventional antifungals, mainly strengthening the antibiofilm activity of fluconazole and 5-flucytosine. Our strategy advances our insights into the development of effective antibiofilm therapeutic approaches.

RevDate: 2020-04-02

Gierl L, Stoy K, Faíña A, et al (2020)

An open-source robotic platform that enables automated monitoring of replicate biofilm cultivations using optical coherence tomography.

NPJ biofilms and microbiomes, 6(1):18 pii:10.1038/s41522-020-0129-y.

The paper introduces a fully automated cultivation and monitoring tool to study biofilm development in replicate experiments operated in parallel. To gain a fundamental understanding of the relation between cultivation conditions and biofilm characteristics (e.g., structural, mechanical) a monitoring setup allowing for the standardization of methods is required. Optical coherence tomography (OCT) is an imaging modality ideal for biofilms since it allows for the monitoring of structure in real time. By integrating an OCT device into the open-source robotic platform EvoBot, a fully automated monitoring platform for investigating biofilm development in several flow cells at once was realized. Different positioning scenarios were tested and revealed that the positioning accuracy is within the optical resolution of the OCT. On that account, a reliable and accurate monitoring of biofilm development by means of OCT has become possible. With this robotic platform, reproducible biofilm experiments including a statistical analysis are achievable with only a small investment of operator time. Furthermore, a number of structural parameters calculated within this study confirmed the necessity to perform replicate biofilm cultivations.

RevDate: 2020-04-02

Ionescu AC, Hahnel S, König A, et al (2020)

Resin composite blocks for dental CAD/CAM applications reduce biofilm formation in vitro.

Dental materials : official publication of the Academy of Dental Materials pii:S0109-5641(20)30071-3 [Epub ahead of print].

OBJECTIVES: Modern dentistry is increasingly focusing on digital procedures, including CAD/CAM technologies. New materials have to resist in a demanding environment that includes secondary caries occurrence. The current study hypothesized that the microbiological behavior of different RBCs for CAD/CAM applications is better than that of their counterparts for direct restorations due to differences in the surface characteristics.

METHODS: Both direct and CAD/CAM RBCs were tested. Specimens were obtained from each group, polished, cleaned, stored in artificial saliva (1w), then sterilized under UV (24h). Specimens' surface was assessed using profilometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction; resin/filler content was assessed using thermogravimetry. After pre-incubation with sterile human saliva (24h), the microbiological behavior of the materials was assessed using four models: Streptococcus mutans adherence (2h), S. mutans biofilm formation in an orbital shaking bioreactor (24h), S. mutans biofilm formation in a continuous-flow bioreactor simulating shear forces (24h), and mixed-plaque formation in the bioreactor (24h). The viable biomass adhering to the specimens' surfaces was measured using a tetrazolium dye-based test. Statistical analysis included verification of normality of distribution and homoscedasticity, then Oneway ANOVA and Tukey's test (α=5%).

RESULTS: When using the bioreactor setup, CAD/CAM RBCs generally yielded lower S. mutans and mixed-plaque biofilm formation compared to direct RBCs. This difference was not evidenced in the first two microbiological models. Differences in manufacturing and curing processes rather than in materials' surface roughness and composition could explain these results.

SIGNIFICANCE: CAD/CAM RBCs are promising materials from a microbiological point of view, featuring reduced biofilm formation on their surfaces when shear conditions similar to in vivo ones are present.

RevDate: 2020-04-02

Vieira TI, Alexandria AK, Menezes JCV, et al (2020)

Characterization and effect of nanocomplexed fluoride solutions on the inhibition of enamel demineralization created by a multispecies cariogenic biofilm model.

Clinical oral investigations pii:10.1007/s00784-020-03261-0 [Epub ahead of print].

OBJECTIVES: The aim of this study was to assess the in vitro caries preventive effect of nanocomplexed solutions of hydroxypropyl-β-cyclodextrin and γ-cyclodextrin associated with titanium tetrafluoride (TiF4) after different complexation times (12 or 72 h).

MATERIALS AND METHODS: Enamel blocks were randomly distributed in 9 groups (n = 11): negative control, hydroxypropyl-β-cyclodextrin, γ-cyclodextrin, TiF4, hydroxypropyl-β-cyclodextrin:TiF4 12 h, hydroxypropyl-β-cyclodextrin:TiF4 72 h, γ-cyclodextrin:TiF4 12 h, γ-cyclodextrin:TiF4 72 h, and NaF (positive control). The solutions were applied for 1 min and the blocks were exposed to a biofilm model. Nanocompounds were characterized by differential scanning calorimetry and X-ray powder diffraction. The percentage of surface microhardness loss (%SML), mineral density changes (ΔZ), lesion depth, surface morphology (scanning electron microscopy-SEM), and chemical characterization (energy-dispersive spectroscopy-EDS) were assessed.

RESULTS: No oxidation was observed, and the formation of the nanocomplexes was evidenced by changes in the melting point compared to pure cyclodextrins and the loss of crystallinity of the materials. Hydroxypropyl-β-cyclodextrin:TiF4 72 h resulted in lower %SML than negative control, hydroxypropyl-β-cyclodextrin, γ-cyclodextrin, and TiF4 (p < 0.05). NaF differed from all groups (p < 0.05), except for hydroxypropyl-β-cyclodextrin:TiF4 72 h (p = 0.83). ΔZ of hydroxypropyl-β-cyclodextrin:TiF4 72 h was higher than negative control, hydroxypropyl-β-cyclodextrin, γ-cyclodextrin, γ-cyclodextrin:TiF4 1 2 h, γ-cyclodextrin:TiF4 72 h, and NaF (p < 0.05) and similar to TiF4 and hydroxypropyl-β-cyclodextrin:TiF4 12 h (p > 0.05). SEM/EDS detected Ti in the blocks subjected to TiF4-products.

CONCLUSION: The hydroxypropyl-β-cyclodextrin:TiF4 72 h solution showed caries preventive effect on the surface and subsurface of the enamel.

CLINICAL RELEVANCE: A hydroxypropyl-β-cyclodextrin nanosystem, in association with TiF4 after 72 h of complexation, may be a promising agent for the prevention of enamel demineralization.

RevDate: 2020-04-02

Kim T, Kim MA, Hwang YC, et al (2020)

Effect of a calcium hydroxide-based intracanal medicament containing N-2-methyl pyrrolidone as a vehicle against Enterococcus faecalis biofilm.

Journal of applied oral science : revista FOB, 28:e20190516 pii:S1678-77572020000100429.

INTRODUCTION: This study investigated the effect of a calcium hydroxide (CH) paste (CleaniCal®) containing N-2-methyl pyrrolidone (NMP) as a vehicle on Enterococcus faecalis (E. faecalis) biofilms compared with other products containing saline (Calasept Plus™) or propylene glycol (PG) (Calcipex II®).

METHODOLOGY: Standardized bovine root canal specimens were used. The antibacterial effects were measured by colony-forming unit counting. The thickness of bacterial microcolonies and exopolysaccharides was assessed using confocal laser scanning microscopy. Morphological features of the biofilms were observed using field-emission scanning electron microscopy (FE-SEM). Bovine tooth blocks covered with nail polish were immersed into the vehicles and dispelling was observed. The data were analyzed using one-way analysis of variance and Tukey tests (p<0.05).

RESULTS: CleaniCal® showed the highest antibacterial activity, followed by Calcipex II® (p<0.05). Moreover, NMP showed a higher antibacterial effect compared with PG (p<0.05). The thickness of bacteria and EPS in the CleaniCal® group was significantly lower than that of other materials tested (p<0.05). FE-SEM images showed the specimens treated with Calasept Plus™ were covered with biofilms, whereas the specimens treated with other medicaments were not. Notably, the specimen treated with CleaniCal® was cleaner than the one treated with Calcipex II®. Furthermore, the nail polish on the bovine tooth block immersed in NMP was completely dispelled.

CONCLUSIONS: CleaniCal® performed better than Calasept Plus™ and Calcipex II® in the removal efficacy of E. faecalis biofilms. The results suggest the effect might be due to the potent dissolving effect of NMP on organic substances.

RevDate: 2020-04-02

Ayoub HM, Gregory RL, Tang Q, et al (2020)

Influence of salivary conditioning and sucrose concentration on biofilm-mediated enamel demineralization.

Journal of applied oral science : revista FOB, 28:e20190501 pii:S1678-77572020000100428.

INTRODUCTION: The acquired pellicle formation is the first step in dental biofilm formation. It distinguishes dental biofilms from other biofilm types.

OBJECTIVE: To explore the influence of salivary pellicle formation before biofilm formation on enamel demineralization.

METHODOLOGY: Saliva collection was approved by Indiana University IRB. Three donors provided wax-stimulated saliva as the microcosm bacterial inoculum source. Acquired pellicle was formed on bovine enamel samples. Two groups (0.5% and 1% sucrose-supplemented growth media) with three subgroups (surface conditioning using filtered/pasteurized saliva; filtered saliva; and deionized water (DIW)) were included (n=9/subgroup). Biofilm was then allowed to grow for 48 h using Brain Heart Infusion media supplemented with 5 g/l yeast extract, 1 mM CaCl2.2H2O, 5% vitamin K and hemin (v/v), and sucrose. Enamel samples were analyzed for Vickers surface microhardness change (VHNchange), and transverse microradiography measuring lesion depth (L) and mineral loss (∆Z). Data were analyzed using two-way ANOVA.

RESULTS: The two-way interaction of sucrose concentration × surface conditioning was not significant for VHNchange (p=0.872), ∆Z (p=0.662) or L (p=0.436). Surface conditioning affected VHNchange (p=0.0079), while sucrose concentration impacted ∆Z (p<0.0001) and L (p<0.0001). Surface conditioning with filtered/pasteurized saliva resulted in the lowest VHNchange values for both sucrose concentrations. The differences between filtered/pasteurized subgroups and the two other surface conditionings were significant (filtered saliva p=0.006; DIW p=0.0075). Growing the biofilm in 1% sucrose resulted in lesions with higher ∆Z and L values when compared with 0.5% sucrose. The differences in ∆Z and L between sucrose concentration subgroups was significant, regardless of surface conditioning (both p<0.0001).

CONCLUSION: Within the study limitations, surface conditioning using human saliva does not influence biofilm-mediated enamel caries lesion formation as measured by transverse microradiography, while differences were observed using surface microhardness, indicating a complex interaction between pellicle proteins and biofilm-mediated demineralization of the enamel surface.

RevDate: 2020-04-02

Bundalovic-Torma C, Whitfield GB, Marmont LS, et al (2020)

A systematic pipeline for classifying bacterial operons reveals the evolutionary landscape of biofilm machineries.

PLoS computational biology, 16(4):e1007721 pii:PCOMPBIOL-D-19-01601.

In bacteria functionally related genes comprising metabolic pathways and protein complexes are frequently encoded in operons and are widely conserved across phylogenetically diverse species. The evolution of these operon-encoded processes is affected by diverse mechanisms such as gene duplication, loss, rearrangement, and horizontal transfer. These mechanisms can result in functional diversification, increasing the potential evolution of novel biological pathways, and enabling pre-existing pathways to adapt to the requirements of particular environments. Despite the fundamental importance that these mechanisms play in bacterial environmental adaptation, a systematic approach for studying the evolution of operon organization is lacking. Herein, we present a novel method to study the evolution of operons based on phylogenetic clustering of operon-encoded protein families and genomic-proximity network visualizations of operon architectures. We applied this approach to study the evolution of the synthase dependent exopolysaccharide (EPS) biosynthetic systems: cellulose, acetylated cellulose, poly-β-1,6-N-acetyl-D-glucosamine (PNAG), Pel, and alginate. These polymers have important roles in biofilm formation, antibiotic tolerance, and as virulence factors in opportunistic pathogens. Our approach revealed the complex evolutionary landscape of EPS machineries, and enabled operons to be classified into evolutionarily distinct lineages. Cellulose operons show phyla-specific operon lineages resulting from gene loss, rearrangement, and the acquisition of accessory loci, and the occurrence of whole-operon duplications arising through horizonal gene transfer. Our evolution-based classification also distinguishes between PNAG production from Gram-negative and Gram-positive bacteria on the basis of structural and functional evolution of the acetylation modification domains shared by PgaB and IcaB loci, respectively. We also predict several pel-like operon lineages in Gram-positive bacteria and demonstrate in our companion paper (Whitfield et al PLoS Pathogens, in press) that Bacillus cereus produces a Pel-dependent biofilm that is regulated by cyclic-3',5'-dimeric guanosine monophosphate (c-di-GMP).

RevDate: 2020-04-02

Cáceres M, Hidalgo W, Stashenko E, et al (2020)

Essential Oils of Aromatic Plants with Antibacterial, Anti-Biofilm and Anti-Quorum Sensing Activities against Pathogenic Bacteria.

Antibiotics (Basel, Switzerland), 9(4): pii:antibiotics9040147.

Both the ability of bacteria to form biofilms and communicate through quorum sensing allows them to develop different survival or virulence traits that lead to increased bacterial resistance against conventional antibiotic therapy. Here, seventeen essential oils (EOs) were investigated for the antimicrobial, antibiofilm, and anti-quorum sensing activities on Escherichia. coli O157:H7, Escherichia coli O33, and Staphylococcus epidermidis ATCC 12228. All essential oils were isolated from plant material by using hydrodistillation and analyzed by GC-MS. The antimicrobial activity was performed by using the microdilution technique. Subinhibitory concentrations of each EO were assayed for biofilm inhibition in both bacterial strains. Quantification of violacein in Chromobacterium violaceum CV026 was performed for the anti-quorum sensing activity. The cytotoxicity activity of the EOs was evaluated on Vero cell line by using MTT method. Thymol-carvacrol-chemotype (I and II) oils from Lippia origanoides and Thymus vulgaris oil exhibited the higher antimicrobial activity with MIC values of 0.37-0.75 mg/mL. In addition, these EOs strongly inhibited the biofilm formation and violacein (QS) production in a concentration-dependent manner, highlighting thymol-carvacrol-chemotype (II) oil as the best candidate for further studies in antibiotic design and development against bacterial resistance.

RevDate: 2020-04-02

Namour M, Verspecht T, El Mobadder M, et al (2020)

Q-Switch Nd:YAG Laser-Assisted Elimination of Multi-Species Biofilm on Titanium Surfaces.

Materials (Basel, Switzerland), 13(7): pii:ma13071573.

(1) Background: The relatively high prevalence of peri-implantitis (PI) and the lack of a standard method for decontamination of the dental implant surface have pushed us to conduct further research in the field. Bacterial biofilms were found to play a primordial role in the etiology of PI. Therefore, the aim is to evaluate the efficacy of a laser-assisted elimination of biofilm protocol in the removal of a multi-species biofilm on titanium surfaces. (2) Methods: In total, 52 titanium discs (grade 4) were used. The study group consisted of 13 titanium disks contaminated with multi-species biofilms and subsequently irradiated with the laser (T + BF + L). The control groups consisted of the following types of titanium disks: 13 contaminated with multi-species biofilms (T + BF), 13 sterile and irradiated (T + L), 13 sterile and untreated (T). Q-Switch Nd:YAG laser Irradiation parameters were the following: energy density equal to 0.597 J/cm2 per pulse, power equal to 270 milliwatt per pulse, 2.4 mm of spot diameter, and 10 Hz repetition rate for pulse duration of six nanoseconds (ns). The laser irradiation was made during 2 s of total time in non-contact and at 0.5 mm away from the titanium disc surface. After treatment, presence of biofilms on the disks was evaluated by staining with crystal violet (CV), which was measured as optical density at six hundred thirty nm, and statistical analyses were done. (3) Results: the optical density values were 0.004 ± 0.004 for the study group T + BF + L, 0.120 ± 0.039 for group T + BF, 0.006 ± 0.003 for group T + L, and 0.007 ± 0.007 for group T. For the study group, laser treatment resulted in a total elimination of the biofilm, with mean values statistically significantly lower than those of contaminated titanium surfaces and similar to those of sterile titanium surfaces. (4) Conclusions: Our irradiation protocol provided a significant elimination of the multi-species biofilm on titanium surfaces. Laser treated titanium surfaces were biofilm-free, similar to the sterile ones.

RevDate: 2020-04-02

Abusrewil S, Alshanta OA, Albashaireh K, et al (2020)

Detection, treatment and prevention of endodontic biofilm infections: what's new in 2020?.

Critical reviews in microbiology [Epub ahead of print].

Endodontic disease, a biofilm infection of the root canal space, is a significant cause of dental morbidity worldwide. Endodontic treatment, or root canal treatment, as it is commonly known is founded on the ability to eradicate microbial biofilm infection and prevent re-infection of the highly complex root canal space. Despite many "advances" in clinical endodontics we have seen little improvement in outcomes. The aim of this critical review paper is to provide a contemporary view of endodontic microbiology and biofilm polymicrobiality, provide an understanding of the host response, and how together these impact upon clinical treatment. Ultimately, it is intended to provide insight into novel opportunities and strategies for the future diagnostics, treatment, and prevention of endodontic disease.

RevDate: 2020-04-02

Rohanizadegan Y, Sonner S, HJ Eberl (2020)

Discrete attachment to a cellulolytic biofilm modeled by an Itô stochastic differential equation.

Mathematical biosciences and engineering : MBE, 17(3):2236-2271.

We propose a mathematical framework for introducing random attachment of bacterial cells in a deterministic continuum model of cellulosic biofilms. The underlying growth model is a highly nonlinear coupled PDE-ODE system. It is regularised and discretised in space. Attachment is described then via an auxiliary stochastic process that induces impulses in the biomass equation. The resulting system is an Itô stochastic differential equation. Unlike the more direct approach of modeling attachment by additive noise, the proposed model preserves non-negativity of solutions. Our numerical simulations are able to reproduce characteristic features of cellulolytic biofilms with cell attachment from the aqueous phase. Grid refinement studies show convergence for the expected values of spatially integrated biomass density and carbon concentration. We also examine the sensitivity of the model with respect to the parameters that control random attachment.

RevDate: 2020-04-01

Li C, Jiang C, Jing H, et al (2020)

Separation of phenolics from peony flowers and their inhibitory activities and action mechanism on bacterial biofilm.

Applied microbiology and biotechnology pii:10.1007/s00253-020-10540-z [Epub ahead of print].

Separation and enrichment of phenolics from peony flowers were performed to improve the anti-biofilm and antibacterial activities for the first time. Through several times of separation, the purity of phenolics components increased significantly, and the anti-biofilm and antibacterial activities of phenolics components against E. coli and S. aureus were also significantly improved. Finally, the phenolics of peony flowers in the eluent of silica gel column chromatography (PPF-ESGCC) were found to exhibit the highest anti-biofilm and antibacterial activities. The inhibition rates of PPF-ESGCC on biofilms of E. coli and S. aureus were 77.93%, and 87.03% respectively, at a very low concentration (1/2 MIC, 0.235 mg/mL). It was found that the biofilm inhibition was achieved by inhibiting their swimming, swarming, twitching motilities, exopolysaccharide (EPS) production, and quorum sensing (QS). Moreover, there was a positive dose-dependent relationship (r = 0.75 to 1) between the inhibition rates and concentrations of PPF-ESGCC during the critical biofilm-formation stage (1-3 days). Chemical composition analysis showed the PPF-ESGCC comprised of gallic acid, kaempferol-7-O-glucoside, and apigenin-7-O-glucoside. In conclusion, PPF-ESGCC exhibited strong inhibitory effect on biofilm formation and gallic acid, kaempferol-7-O-glucoside, and apigenin-7-O-glucoside might play a crucial role in inhibiting biofilm formation. Meanwhile, this study indicated that PPF-ESGCC, a new natural QS inhibitor and biofilm inhibitor, could be used as a novel intervention strategy to enhance the safety and quality of food.

RevDate: 2020-04-01

Qian Y, Altamimi A, Yates SA, et al (2020)

H2S-releasing amphiphilic dipeptide hydrogels are potent S. aureus biofilm disruptors.

Biomaterials science [Epub ahead of print].

As a gasotransmitter, hydrogen sulfide (H2S) has been studied to treat wounds and inflammation, but its potential antimicrobial effects in this context have not been evaluated. An H2S-releasing dipeptide hydrogel (S-FE), and several non-H2S-releasing control dipeptides, (C-FE, C-GE, FBA-FE, and FE where S = S-aroylthiooxime, an H2S donor; C = control, an oxime incapable of H2S release; FBA = 4-formylbenzamide, also incapable of H2S release; and E, F, G = glutamic acid, phenylalanine, and glycine, respectively), were studied to correlate differences in their chemical structures and H2S-releasing abilities with their antimicrobial effects on Staphylococcus aureus bacteria. Dipeptides with Phe (S-FE, C-FE, and FE) self-assembled into nanoribbons in water and displayed β-sheet formation and enhanced fluorescence, while the other two dipeptides (FBA-FE and C-GE) did not form assemblies in water. In vitro experiments with Staphylococcus aureus, which is a commonly found bacterium associated with wounds, showed significant antimicrobial effects from some of the dipeptides. Dipeptide S-FE inhibited bacterial growth more effectively than any of the controls, thereby limiting biofilm formation or disrupting established biofilms. These antimicrobial H2S-releasing dipeptide hydrogels provide a promising new approach to treat wound infections.

RevDate: 2020-04-01

Dean SN, Milton ME, Cavanagh J, et al (2020)

Francisella novicida Two-Component System Response Regulator BfpR Modulates iglC Gene Expression, Antimicrobial Peptide Resistance, and Biofilm Production.

Frontiers in cellular and infection microbiology, 10:82.

Response regulators are a critical part of the two-component system of gene expression regulation in bacteria, transferring a signal from a sensor kinase into DNA binding activity resulting in alteration of gene expression. In this study, we investigated a previously uncharacterized response regulator in Francisella novicida, FTN_1452 that we have named BfpR (Biofilm-regulating Francisella protein Regulator, FTN_1452). In contrast to another Francisella response regulator, QseB/PmrA, BfpR appears to be a negative regulator of biofilm production, and also a positive regulator of antimicrobial peptide resistance in this bacterium. The protein was crystallized and X-ray crystallography studies produced a 1.8 Å structure of the BfpR N-terminal receiver domain revealing interesting insight into its potential interaction with the sensor kinase. Structural analysis of BfpR places it in the OmpR/PhoP family of bacterial response regulators along with WalR and ResD. Proteomic and transcriptomic analyses suggest that BfpR overexpression affects expression of the critical Francisella virulence factor iglC, as well as other proteins in the bacterium. We demonstrate that mutation of bfpR is associated with an antimicrobial peptide resistance phenotype, a phenotype also associated with other response regulators, for the human cathelicidin peptide LL-37 and a sheep antimicrobial peptide SMAP-29. F. novicida with mutated bfpR replicated better than WT in intracellular infection assays in human-derived macrophages suggesting that the down-regulation of iglC expression in bfpR mutant may enable this intracellular replication to occur. Response regulators have been shown to play important roles in the regulation of bacterial biofilm production. We demonstrate that F. novicida biofilm formation was highly increased in the bfpR mutant, corresponding to altered glycogen synthesis. Waxworm infection experiments suggest a role of BfpR as a negative modulator of iglC expression with de-repression by Mg2+. In this study, we find that the response regulator BfpR may be a negative regulator of biofilm formation, and a positive regulator of antimicrobial peptide resistance in F. novicida.

RevDate: 2020-04-01

Papaianni M, Cuomo P, Fulgione A, et al (2020)

Bacteriophages Promote Metabolic Changes in Bacteria Biofilm.

Microorganisms, 8(4): pii:microorganisms8040480.

Bacterial biofilm provides bacteria with resistance and protection against conventional antimicrobial agents and the host immune system. Bacteriophages are known to move across the biofilm to make it permeable to antimicrobials. Mineral hydroxyapatite (HA) can improve the lytic activity of bacteriophages, and, together with eicosanoic acid (C20:0), can destroy the biofilm structure. Here, we demonstrate the efficacy of the combined use of phage, HA and C20:0 against Xanthomonascampestris pv campestris (Xcc) biofilm. We used nuclear magnetic resonance (NMR)-based metabolomics to investigate the molecular determinants related to the lytic action, aiming at identifying the metabolic pathways dysregulated by phage treatment. Furthermore, we identified specific markers (amino acids, lactate and galactomannan) which are involved in the control of biofilm stability. Our data show that Xccφ1, alone or in combination with HA and C20:0, interferes with the metabolic pathways involved in biofilm formation. The approach described here might be extended to other biofilm-producing bacteria.

RevDate: 2020-04-01

Mettrick K, Hassan K, Lamont I, et al (2020)

The Iron-chelator, N,N'-bis (2-hydroxybenzyl) Ethylenediamine-N,N'-Diacetic acid is an Effective Colistin Adjunct against Clinical Strains of Biofilm-Dwelling Pseudomonas aeruginosa.

Antibiotics (Basel, Switzerland), 9(4): pii:antibiotics9040144.

Targeting the iron requirement of Pseudomonas aeruginosa may be an effective adjunctive for conventional antibiotic treatment against biofilm-dwelling P. aeruginosa. We, therefore, assessed the anti-biofilm activity of N,N'-bis (2-hydroxybenzyl) ethylenediamine-N,N'-diacetic acid (HBED), which is a synthetic hexadentate iron chelator. The effect of HBED was studied using short-term (microtitre plate) and longer-term (flow-cell) biofilm models, under aerobic, anaerobic, and microaerobic (flow-cell) conditions and in combination with the polymyxin antibiotic colistimethate sodium (colistin). HBED was assessed against strains of P. aeruginosa from patients with cystic fibrosis and the reference strain PAO1. HBED inhibited growth and biofilm formation of all clinical strains under aerobic and anaerobic conditions, but inhibitory effects against PAO1 were predominantly exerted under anaerobic conditions. PA605, which is a clinical strain with a robust biofilm-forming phenotype, was selected for flow-cell studies. HBED significantly reduced biomass and surface coverage of PA605, and, combined with colistin, HBED significantly enhanced the microcolony killing effects of colistin to result in almost complete removal of the biofilm. HBED combined with colistin is highly effective in vitro against biofilms formed by clinical strains of P. aeruginosa.

RevDate: 2020-04-01

Ríos-Castillo AG, Ripolles-Avila C, JJ Rodríguez-Jerez (2020)

Detection of Salmonella Typhimurium and Listeria monocytogenes biofilm cells exposed to different drying and pre-enrichment times using conventional and rapid methods.

International journal of food microbiology, 324:108611 pii:S0168-1605(20)30105-7 [Epub ahead of print].

The capacity of real-time PCR (RT-PCR), the VIDAS immunoassay system, and the conventional count method for detecting Salmonella enterica serovar Typhimurium and Listeria monocytogenes biofilm cells was evaluated in this study. After biofilm formation, tests were performed under different drying times (0, 6, 12, 24, and 72 h) and pre-enrichment times (0, 6, 18, and 25 h). The direct epifluorescence microscopic results demonstrated that Salmonella Typhimurium and L. monocytogenes biofilm cells can remain viable for 72 h under drying conditions. Pre-enrichment time and type of medium played an essential role in the detection of both microorganisms after drying. Furthermore, RT-PCR was more sensitive than VIDAS and the conventional method for detecting Salmonella Typhimurium and L. monocytogenes cells at different drying times and without pre-enrichment (0 h), with a detection range between 102 and 107 CFU/mL. TSBYE-T80 used as a pre-enrichment medium was effective for detecting both bacteria and was more effective than Demi Fraser-T80 medium for detecting L. monocytogenes. Therefore, pre-enrichment is recommended to avoid false positives and false negatives due to the presence of dead cells or a very low initial concentration of cells after drying.

RevDate: 2020-04-01

Srivastava GN, Malwe AS, Sharma AK, et al (2020)

A machine learning based classification tool for the prediction of biofilm inhibitory molecules.

Genomics pii:S0888-7543(19)30549-X [Epub ahead of print].

Identification of biofilm inhibitory small molecules appears promising for therapeutic intervention against biofilm-forming bacteria. However, the experimental identification of such molecules is a time-consuming task, and thus, the computational approaches emerge as promising alternatives. We developed the 'Molib' tool to predict the biofilm inhibitory activity of small molecules. We curated a training dataset of biofilm inhibitory molecules, and the structural and chemical features were used for feature selection, followed by algorithms optimization and building of machine learning-based classification models. On five-fold cross validation, Random Forest-based descriptor, fingerprint and hybrid classification models showed accuracies of 0.93, 0.88 and 0.90, respectively. The performances of all models were evaluated on two different validation datasets including biofilm inhibitory and non-inhibitory molecules, attesting to its accuracy (≥ 0.90). The Molib web server would serve as a highly useful and reliable tool for the prediction of biofilm inhibitory activity of small molecules.

RevDate: 2020-03-31

Santiago AJ, Burgos-Garay ML, Kartforosh L, et al (2020)

Bacteriophage treatment of carbapenemase-producing Klebsiella pneumoniae in a multispecies biofilm: a potential biocontrol strategy for healthcare facilities.

AIMS microbiology, 6(1):43-63 pii:microbiol-06-01-003.

The p-traps of hospital handwashing sinks represent a potential reservoir for antimicrobial-resistant organisms of major public health concern, such as carbapenemase-producing KPC+ Klebsiella pneumoniae (CPKP). Bacteriophages have reemerged as potential biocontrol agents, particularly against biofilm-associated, drug-resistant microorganisms. The primary objective of our study was to formulate a phage cocktail capable of targeting a CPKP strain (CAV1016) at different stages of colonization within polymicrobial drinking water biofilms using a CDC biofilm reactor (CBR) p-trap model. A cocktail of four CAV1016 phages, all exhibiting depolymerase activity, were isolated from untreated wastewater using standard methods. Biofilms containing Pseudomonas aeruginosa, Micrococcus luteus, Stenotrophomonas maltophilia, Elizabethkingia anophelis, Cupriavidus metallidurans, and Methylobacterium fujisawaense were established in the CBR p-trap model for a period of 28 d. Subsequently, CAV1016 was inoculated into the p-trap model and monitored over a period of 21 d. Biofilms were treated for 2 h at either 25 °C or 37 °C with the phage cocktail (109 PFU/ml) at 7, 14, and 21 d post-inoculation. The effect of phage treatment on the viability of biofilm-associated CAV1016 was determined by plate count on m-Endo LES agar. Biofilm heterotrophic plate counts (HPC) were determined using R2A agar. Phage titers were determined by plaque assay. Phage treatment reduced biofilm-associated CAV1016 viability by 1 log10 CFU/cm2 (p < 0.05) at 7 and 14 d (37 °C) and 1.4 log10 and 1.6 log10 CFU/cm2 (p < 0.05) at 7 and 14 d, respectively (25 °C). No significant reduction was observed at 21 d post-inoculation. Phage treatment had no significant effect on the biofilm HPCs (p > 0.05) at any time point or temperature. Supplementation with a non-ionic surfactant appears to enhance phage association within biofilms. The results of this study suggest the potential of phages to control CPKP and other carbapenemase-producing organisms associated with microbial biofilms in the healthcare environment.

RevDate: 2020-03-31

Hu J, Wang C, Shao B, et al (2020)

Enhanced formation of carbonaceous and nitrogenous disinfection byproducts from biofilm extracellular polymeric substances undercatalysis of copper corrosion products.

The Science of the total environment, 723:138160 pii:S0048-9697(20)31673-9 [Epub ahead of print].

Biofilm formation is ubiquitous on the corroded inner surface of water distribution pipes. Extracellular polymeric substances (EPS) secreted by biofilm microorganisms are nonnegligible precursors of disinfection byproducts (DBPs). The aim was to study the catalysis of copper corrosion products (CCPs, CuO and Cu2+) on the formation of carbonaceous and nitrogenous DBPs (C-DBPs and N-DBPs) with EPS as a precursor. Results indicate that CCPs had a remarkable enhancement on the formation of DBPs, especially N-DBPs. The enhancement by Cu2+ was mainly via homogeneous catalysis initiating from its complexation with EPS, while that by CuO was primarily through heterogeneous catalysis initiating from the polarization of Cl atom in HOCl/OCl-. The enhancement was more evident as pH increased because an alkaline condition favored the electrostatic interactions of CCPs with EPS and HOCl/OCl-. The presence of Br- weakened the enhancement, which may be attributed to that HOBr/OBr- had a much higher reaction rate than HOCl/OCl- towards the low reactive moieties in EPS. Due to more phenolic or unsaturated/conjugated groups, EPS proteins had a higher catalytic formation of DBPs than EPS polysaccharides. Among the major amino acids in EPS proteins for DBPs formation, tyrosine had the highest enhancement on the formation of trihalomethanes, while histidine had the highest catalytic formation of halogenated acetic acids, acetonitriles and acetamides. The study helps to understand the formation of DBPs by the joint actions of EPS and CCPs in drinking water distribution systems.

RevDate: 2020-03-31

Qais FA, Shafiq A, Ahmad I, et al (2020)

Green synthesis of silver nanoparticles using Carum copticum: Assessment of its quorum sensing and biofilm inhibitory potential against Gram negative bacterial pathogens.

Microbial pathogenesis pii:S0882-4010(20)30459-9 [Epub ahead of print].

Antimicrobial resistance among pathogenic bacteria has become a global threat to human health. Due to poor progress in development of new antimicrobial drugs, there is greater need for the development of novel alternative strategies to combat problem of multidrug resistance. Moreover, there is focus on ecofriendly approach for the synthesis nanoparticles having efficient medicinal properties including antivirulence properties to tackle the emergence of multi-drug resistance. Targeting quorum sensing controlled virulence factors, and biofilms has come out to be a novel anti-infective drug target. The silver nanoparticles (Ag@CC-NPs) were synthesized from aqueous extract of Carum copticum and characterized using UV-vis absorption spectroscopy, fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Ag@CC-NPs were checked for its ability to inhibit quorum sensing-mediated virulence factors and biofilms against three test pathogens at sub-MIC values. There was ∼75% inhibition of violacein production by Ag@CC-NPs against C. violaceum. The P. aeruginosa virulence factors such as pyocyanin production, pyoverdin production, exoprotease activity, elastase activity, swimming motility and rhamnolipid production were inhibited by 76.9, 49.0, 71.1, 53.3, 89.5, and 60.0% at sub-MIC. Moreover, virulence factors of S. marcescens viz. prodigiosin production, exoprotease activity, and swarming motility was reduced by 78.4, 67.8, and 90.7%. Ag@CC-NPs also exhibited broad-spectrum antibiofilm activity with 77.6, 86.3, and 75.1% inhibition of biofilms of P. aeruginosa, S. marcescens, and C. violaceum respectively. The biofilm formation on coverslip was reduced remarkably as evident from SEM and CLSM analysis. The findings revealed the in vitro efficacy of Ag@CC-NPs against bacterial pathogens and can be exploited in the development of alternative therapeutic agent in management of bacterial infections for topical application, mainly wound infection, or coating of surface to prevent bacterial adherence on medical devices.

RevDate: 2020-03-31

Hamada M, Yamaguchi T, Ishii Y, et al (2020)

Inhibitory effect of fidaxomicin on biofilm formation in Clostridioides difficile.

Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy pii:S1341-321X(20)30062-3 [Epub ahead of print].

Clostridioides difficile infection results from a disturbance of the normal microbial flora of the colon, allowing proliferation of C. difficile and toxin production by toxigenic strains. Fidaxomicin, a macrocyclic antibiotic that prevents RNA synthesis in C. difficile and inhibits spore formation, toxin production, and cell proliferation, is clinically effective in treating C. difficile infection. As recent studies have suggested that biofilm formation influences C. difficile colonization and infection in the colon, we undertook the present study to determine the effects of fidaxomicin on C. difficile biofilm formation. Sub-minimum inhibitory concentrations (MICs) of fidaxomicin inhibited biofilm formation by C. difficile UK027 and delayed planktonic growth. Sub-MICs of vancomycin did not inhibit biofilm formation or affect planktonic growth. In C. difficile UK027 exposed to sub-MICs of fidaxomicin, mRNA expression of biofilm-related flagellin gene fliC was slightly increased compared with that of other biofilm-related genes (pilA1, cwp84, luxS, dccA, and spo0A). In conclusion, this study indicates that sub-MICs of fidaxomicin inhibit C. difficile UK027 biofilm formation by influencing cell growth and fliC transcription.

RevDate: 2020-03-29

Caraballo Guzmán A, González Hurtado MI, Cuesta-Astroz Y, et al (2020)

Metagenomic characterization of bacterial biofilm in four food processing plants in Colombia.

Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology] pii:10.1007/s42770-020-00260-x [Epub ahead of print].

Bacteria inside biofilms are more persistent and resistant to stress conditions found in the production environment of food processing plants, thus representing a constant risk for product safety and quality. Therefore, the aim of this study was to characterize, using 16S rRNA sequencing, the bacterial communities from biofilms found in four food processing plants (P1, P2, P3, and P4). In total, 50 samples from these four processing plants were taken after cleaning and disinfection processes. Four phyla: Proteobacteria, Firmicutes, Actinobacteria, and Bacteroides represented over 94% of the operational taxonomic units found across these four plants. A total of 102 families and 189 genera were identified. Two genera, Pseudomonas spp. and Acinetobacter spp., were the most frequently found (93.47%) across the four plants. In P1, Pseudomonas spp. and Lactobacillus spp. were the dominant genera, whereas Lactobacillus spp. and Streptococcus spp. were identified in P2. On the other hand, biofilms found in P3 and P4 mainly consisted of Pseudomonas spp. and Acinetobacter spp. Our results indicate that different bacterial genera of interest to the food industry due to their ability to form biofilm and affect food quality can coexist inside biofilms, and as such, persist in production environments, representing a constant risk for manufactured foods. In addition, the core microbiota identified across processing plants evaluated was probably influenced by type of food produced and cleaning and disinfection processes performed in each one of these.

RevDate: 2020-03-29

Anonymous (2020)

Biofilm management.

British dental journal, 228(6):481.

RevDate: 2020-03-29

Taglialegna A, Matilla-Cuenca L, Dorado-Morales P, et al (2020)

The biofilm-associated surface protein Esp of Enterococcus faecalis forms amyloid-like fibers.

NPJ biofilms and microbiomes, 6(1):15 pii:10.1038/s41522-020-0125-2.

Functional amyloids are considered as common building block structures of the biofilm matrix in different bacteria. In previous work, we have shown that the staphylococcal surface protein Bap, a member of the Biofilm-Associated Proteins (BAP) family, is processed and the fragments containing the N-terminal region become aggregation-prone and self-assemble into amyloid-like structures. Here, we report that Esp, a Bap-orthologous protein produced by Enterococcus faecalis, displays a similar amyloidogenic behavior. We demonstrate that at acidic pH the N-terminal region of Esp forms aggregates with an amyloid-like conformation, as evidenced by biophysical analysis and the binding of protein aggregates to amyloid-indicative dyes. Expression of a chimeric protein, with its Esp N-terminal domain anchored to the cell wall through the R domain of clumping factor A, showed that the Esp N-terminal region is sufficient to confer multicellular behavior through the formation of an extracellular amyloid-like material. These results suggest that the mechanism of amyloid-like aggregation to build the biofilm matrix might be widespread among BAP-like proteins. This amyloid-based mechanism may not only have strong relevance for bacteria lifestyle but could also contribute to the amyloid burden to which the human physiology is potentially exposed.

RevDate: 2020-03-29

Yu S, Jiang B, Jia C, et al (2020)

Investigation of biofilm production and its association with genetic and phenotypic characteristics of OM (osteomyelitis) and non-OM orthopedic Staphylococcus aureus.

Annals of clinical microbiology and antimicrobials, 19(1):10 pii:10.1186/s12941-020-00352-4.

BACKGROUND: Staphylococcus aureus is a primary pathogen of orthopedic infections. By mediating antimicrobial resistance, S. aureus biofilm plays an important role in the recalcitrance of orthopedic infections, especially for the intractable osteomyelitis (OM). This study investigated the relationship between biofilm production and various genetic or phenotypic characteristics among orthopedic S. aureus strains.

METHODS: A total of 137 orthopedic S. aureus isolates were enrolled and divided into OM and non-OM groups. Biofilm production was evaluated using the crystal violet assay. Genetic and phenotypic characteristics including MRSA identification, MLST and spa typing, carriage of virulence genes, drug resistance, and patients' inflammatory responses indicators were characterized. The relationship between biofilm production and above-mentioned features was respectively analyzed among all isolates and compared between OM and non-OM isolates.

RESULTS: Biofilm production presented no significant difference between OM (including 9 MRSA isolates) and non-OM (including 21 MRSA isolates) strains. We found that ST88, t377 and ST630-MSSA-t377 strains produced very strong biofilms, while MLST types of ST15, ST25, ST398, ST5, ST59 and spa types of t002, t2325, t437 tended to produce weaker biofilms. Strains with the following profiles produced stronger biofilms: fib(+)-hlgv(+)-lukED(+)-sei(-)-sem(-)-seo(-) for all isolates, sei(-)-sem(-)-seo(-) for OM isolates, and cna (+)-fib (+)-hlgv (+)-lukED (+)-seb(-)-sed(-) for non-OM isolates. In addition, not any single drug resistance was found to be related to biofilm production. We also observed that, among OM patients, strains with stronger biofilms caused weaker inflammatory responses.

CONCLUSION: Some genetic or phenotypic characteristics of orthopedic strains were associated with biofilm production, and this association could be different among OM and non-OM strains. The results are of great significance for better understanding, evaluating and managing different kinds of biofilm-associated orthopedic infections, and provide potential targets for biofilm clearance.

RevDate: 2020-03-28

Reamtong O, Indrawattana N, Rungruengkitkun A, et al (2020)

Altered proteome of a Burkholderia pseudomallei mutant defective in short-chain dehydrogenase affects cell adhesion, biofilm formation and heat stress tolerance.

PeerJ, 8:e8659 pii:8659.

Burkholderia pseudomallei is a Gram-negative bacillus that causes melioidosis and is recognized as an important public health problem in southeast Asia and northeast Australia. The treatment of B. pseudomallei infection is hampered by resistance to a wide range of antimicrobial agents and no vaccine is currently available. At present, the underlying mechanisms of B. pseudomallei pathogenesis are poorly understood. In our previous study, we reported that a B. pseudomallei short-chain dehydrogenase (SDO; BPSS2242) mutant constructed by deletion mutagenesis showed reduced B. pseudomallei invasion and initial intracellular survival. This indicated that SDO is associated with the pathogenesis of melioidosis. In the present study, the role of B. pseudomallei SDO was further investigated using the SDO deletion mutant by a proteomic approach. The protein profiles of the SDO mutant and wild-type K96243 were investigated through gel-based proteomic analysis. Quantitative intensity analysis of three individual cultures of the B. pseudomallei SDO mutant revealed significant down-regulation of five protein spots compared with the wild-type. Q-TOF MS/MS identified the protein spots as a glutamate/aspartate ABC transporter, prolyl-tRNA synthetase, Hsp70 family protein, quinone oxidoreductase and a putative carboxypeptidase. Functional assays were performed to investigate the role of these differentially expressed proteins in adhesion to host cells, biofilm induction and survival under heat stress conditions. The SDO deletion mutant showed a decreased ability to adhere to host cells. Moreover, biofilm formation and the survival rate of bacteria under heat stress conditions were also reduced in the mutant strain. Our findings provide insight into the role of SDO in the survival and pathogenesis of B. pseudomallei at the molecular level, which may be applied to the prevention and control of B. pseudomallei infection.

RevDate: 2020-03-27

Casar CP, Kruger BR, Flynn TM, et al (2020)

Mineral-hosted biofilm communities in the continental deep subsurface, Deep Mine Microbial Observatory, SD, USA.

Geobiology [Epub ahead of print].

Deep subsurface biofilms are estimated to host the majority of prokaryotic life on Earth, yet fundamental aspects of their ecology remain unknown. An inherent difficulty in studying subsurface biofilms is that of sample acquisition. While samples from marine and terrestrial deep subsurface fluids have revealed abundant and diverse microbial life, limited work has described the corresponding biofilms on rock fracture and pore space surfaces. The recently established Deep Mine Microbial Observatory (DeMMO) is a long-term monitoring network at which we can explore the ecological role of biofilms in fluid-filled fractures to depths of 1.5 km. We carried out in situ cultivation experiments with single minerals representative of DeMMO host rock to explore the ecological drivers of biodiversity and biomass in biofilm communities in the continental subsurface. Coupling cell densities to thermodynamic models of putative metabolic reactions with minerals suggests a metabolic relationship between biofilms and the minerals they colonize. Our findings indicate that minerals can significantly enhance biofilm cell densities and promote selective colonization by taxa putatively capable of extracellular electron transfer. In turn, minerals can drive significant differences in biodiversity between fluid and biofilm communities. Given our findings at DeMMO, we suggest that host rock mineralogy is an important ecological driver in deep continental biospheres.

RevDate: 2020-03-27

Velichko NS, Grinev VS, YP Fedonenko (2020)

Characterization of biopolymers produced by planktonic and biofilm cells of Herbaspirillum lusitanum P6-12.

Journal of applied microbiology [Epub ahead of print].

AIMS: The goal of this study was to characterize the Herbaspirillum lusitanum P6-12 biopolymers under various environmental conditions.

METHODS AND RESULTS: Differences in biopolymers composition from planktonic and biofilm cells of H. lusitanum strain P6-12 were analyzed using Fourier transform infrared spectroscopy (FTIR), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and colorimetric and gas-liquid chromatography (GLC). A high degree of polymer separation and purification was achieved by ultracentrifugation, and column chromatography allowed us to identify the chemical differences between biopolymers from biofilm and planktonic Herbaspirillum lusitanum. The planktonic cells of H. lusitanum P6-12 had capsules containing two high-molecular-weight glycoconjugates (CPS-I and CPS-II) of a lipopolysaccharide (LPS) nature and one EPS as a lipid-polysaccharide complex. The EPS, CPS-I, CPS-II had different monosaccharide and lipid compositions. The extracellular polymeric matrix (EPM) produced by the biofilm cells was mostly proteinaceous, with a small amount of carbohydrates (up to 3%). From the biofilm culture medium, a free extracellular polymeric substance (fEPS) was obtained that contained proteins and carbohydrates (up to 7%). The cells outside the biofilm produced capsules (CPSFBC) that consisted of carbohydrates (up to 10%), proteins (up to 16%), and lipids.

CONCLUSIONS: During biofilm formation, the bacteria secreted surface biopolymers that differed from those of the planktonic cells. The heterogeneity of the polysaccharidic polymers of the H. lusitanum P6-12 surface is probably conditioned by their different functions in plant colonization and formation of an efficient symbiosis, as well as in cell adaptation to existence in plant tissues.

The results of the study permit a better understanding of the physiological properties of the biopolymers, e.g., in plant-microbe interactions.

RevDate: 2020-03-27

Kaur A, Capalash N, P Sharma (2020)

Expression of Meiothermus ruber luxS in E. coli alters the antibiotic susceptibility and biofilm formation.

Applied microbiology and biotechnology pii:10.1007/s00253-020-10480-8 [Epub ahead of print].

Quorum sensing (QS) and signal molecules used for interspecies communication are well defined in mesophiles, but there is still a plethora of microorganisms in which existence and mechanisms of QS need to be explored, thermophiles being among them. In silico analysis has revealed the presence of autoinducer-2 (AI-2) class of QS signaling molecules in thermophiles, synthesized by LuxS (AI-2 synthase), though the functions of this system are not known. In this study, LuxS of Meiothermus ruber was used for understanding the mechanism and functions of AI-2 based QS among thermophilic bacteria. The luxS gene of M. ruber was expressed in luxS- deletion mutant of Escherichia coli. Complementation of luxS resulted in significant AI-2 activity, enhanced biofilm formation, and antibiotic susceptibility. Transcriptome analysis showed significant differential expression of 204 genes between the luxS-complemented and luxS- deletion mutant of E. coli. Majority of the genes regulated by luxS belonged to efflux pumps. This elucidation may contribute towards finding novel alternatives against incessant antibiotic resistance in bacteria.Key Points • Expression of luxS in luxS - E. coli resulted in increase in biofilm index. • Reduction in the MIC of antibiotics was observed after complementation of luxS. • Downregulation of efflux pump genes was observed after complementation of luxS. • Transcriptome analysis showed that 204 genes were differentially regulated significantly.

RevDate: 2020-03-27

Kırmusaoğlu S, H Kaşıkçı (2020)

Identification of ica-dependent biofilm production by Staphylococcus aureus clinical isolates and antibiofilm effects of ascorbic acid against biofilm production.

Journal of clinical pathology pii:jclinpath-2019-206280 [Epub ahead of print].

AIMS: Staphylococcus aureus (S. aureus) is a life-threatening pathogen with high morbidity and mortality rates which causes nosocomial and community-acquired infections. Biofilm, considered to be a common virulence factor for pathogens, plays a significant role in recurrent and untreatable infections. Biofilm formation of S. aureus is mediated by synthesis of either poly-N-acetylglucosamine in an ica-dependent manner or surface proteins in an ica-independent manner. In some cases treatment is impossible and recurrent. In this study, ica-dependent biofilm-producing S. aureus isolates were detected and the anti-biofilm effect of ascorbic acid against biofilm formation of isolates was investigated.

METHODS: A total of 21 methicillin-sensitive S. aureus (MSSA) clinical isolates stored in our bacterial stock were used to detect ica-dependent biofilm-producing MSSA isolates. The anti-biofilm study was undertaken with three ica-dependent biofilm-producing isolates (MSSA2-4) and ATCC 29213 (MSSA1). Biofilms and the anti-biofilm effect of ascorbic acid were detected using the microtitre plate (MtP) method. 16S-rRNA, nuc, icaA and icaD genes and expression levels of icaA and icaD of isolates were detected by RT-PCR.

RESULTS: The minimum inhibitory concentrations (MICs) of ascorbic acid prevented biofilm formation of MSSA1 and MSSA3. Also, 1/2 MIC of ascorbic acid prevented biofilm formation of MSSA3. It was observed that biofilm formation decreased with increased concentration. There was no significant increase in ica gene expression of MSSA1 and MSSA2. Expression of icaA and icaD of MSSA3 decreased 13% and 38%, respectively. Expression of icaA in MSSA4 decreased 12%.

CONCLUSION: The results of our study show that ascorbic acid can be used as an anti-biofilm agent to prevent biofilm formation of S. aureus and thus biofilm-related infections.

RevDate: 2020-03-26

Qiao Z, Yao Y, Song S, et al (2020)

Gold nanorods with surface charge-switchable activities for enhanced photothermal killing of bacteria and eradication of biofilm.

Journal of materials chemistry. B [Epub ahead of print].

The increasing growth and severity of bacterial biofilm infections and the appearance of multidrug-resistant bacteria pose alarming threats to public healthcare systems, mainly due to their formidable tolerance to conventional antibiotics. Different from the antibacterial mechanisms of antibiotics, gold nanorods (AuNRs) disinfect microbes by local heating induced by near-infrared (NIR) light irradiation; thus, they are potential disinfection agents. In an attempt to increase the biocompatibility and antibacterial activities of AuNRs against organisms in both planktonic and biofilm phenotypes, polymethacrylate with pendant carboxyl betaine groups was decorated on AuNRs (PCB-AuNRs) to afford AuNRs with pH-induced surface charge-transformable activities. The zwitterion-modified AuNRs demonstrated a pH-responsive transition from negative charge to positive charge; this confers the AuNRs with a change in functionality from biocompatible zwitterionic nanocomposites in healthy tissues (pH = ∼7.4) to enhanced antimicrobial cationic nanocomposites at acidic bacterial infection sites (pH = ∼5.5). AuNRs coated by polymethacrylate with pendant mPEG (PPEGMA-AuNRs) without surface charge transition activities were used for comparison. PCB-AuNRs presented better antimicrobial activity against Gram-negative bacteria (E. coli), Gram-positive bacteria (S. aureus) and their drug-resistant strains (MRSA and EBSL E. coli) than PPEGMA-AuNRs as a result of their pH-responsive surface charge transition activities. Moreover, PCB-AuNRs demonstrated deeper penetration into mature biofilms and better biofilm elimination activities than their non-surface charge-transformable counterparts. The results indicate that the designed zwitterion-coated AuNRs are a promising antibacterial agent for fighting bacterial infections.

RevDate: 2020-03-26

Zhong X, Wu Q, Zhang J, et al (2020)

Campylobacter jejuni Biofilm Formation Under Aerobic Conditions and Inhibition by ZnO Nanoparticles.

Frontiers in microbiology, 11:207.

Campylobacter jejuni is a major foodborne pathogen worldwide. As it forms biofilms, it can become a persistent contaminant in the food and pharmaceutical industries. In this study, it was demonstrated that C. jejuni could make more biofilm in aerobic conditions than in microaerobic conditions, and only 13.9% C. jejuni entered coccus (a VBNC state) under microaerobic conditions; however, the rate increased to 95.5% under aerobic conditions. C. jejuni could form more biofilm in mixed culture with Escherichia coli or Pseudomonas aeruginosa than in pure culture. Scanning electron microscope results showed that C. jejuni retained its normal spiral shape under aerobic conditions for 48 h by forming crosslinks with the aerobic and facultative anaerobic bacteria. Additionally, culture medium containing 0.5 mg/ml ZnO nanoparticles inhibited biofilm formation. Our results provide information on a new approach to controlling contamination via C. jejuni.

RevDate: 2020-03-26

Topa SH, Palombo EA, Kingshott P, et al (2020)

Activity of Cinnamaldehyde on Quorum Sensing and Biofilm Susceptibility to Antibiotics in Pseudomonas aeruginosa.

Microorganisms, 8(3): pii:microorganisms8030455.

Quorum sensing (QS) plays an important role during infection for the opportunistic human pathogen Pseudomonas aeruginosa. Quorum sensing inhibition (QSI) can disrupt this initial event of infection without killing bacterial cells, and thus QS inhibitors have been suggested as novel approaches for anti-infective therapy. Cinnamaldehyde (CAD) is a P. aeruginosa biofilm inhibitor and disperser of preformed biofilms. In this study, the combined use of CAD and colistin (COL) revealed a synergistic activity, but this was not the case for CAD combined with carbenicillin, tobramycin (TOB), or erythromycin in checkerboard assays for P. aeruginosa. CAD demonstrated QSI activity by repression of the expression of lasB, rhlA and pqsA in GFP reporter assays. Approximately 70% reduction in GFP production was observed with the highest CAD concentration tested in all the QS reporter strains. TOB also showed strong QSI when combined with CAD in reporter assays. Combination treatments revealed an additive activity of CAD with COL and TOB in biofilm inhibition (75.2% and 83.9%, respectively) and preformed biofilm dispersion (~90% for both) when compared to the individual treatments. Therefore, a proposed method to mitigate P. aeruginosa infection is a combination therapy of CAD with COL or CAD with TOB as alternatives to current individual drug therapies.

RevDate: 2020-03-26

Emad F, Khalafalah AK, El Sayed MA, et al (2020)

Three new polyacetylene glycosides (PAGs) from the aerial part of Launaea capitata (Asteraceae) with anti-biofilm activity against Staphylococcus aureus.

Fitoterapia pii:S0367-326X(20)30130-1 [Epub ahead of print].

Four polyacetylenic glycosides, three of which are new, together with two known flavonoids were isolated from the methanol extract of the aerial parts of Launaea capitate, designated bidensyneoside A1 (1), 6´-O-acetyl-bidensyneoside A1 (2), bidensyneoside E (3), bidensyneoside F (4), luteolin (5) and luteolin-7-glucoside (6) also known as cynaroside. Their structures were elucidated by comprehensive analysis of 1D, 2D-NMR and HR-MS data. The absolute configuration of bidensyneosides was determined by Mosher ester analysis and the optical rotation values. The isolated compounds were tested against biofilm formation of Staphylococcus aureus as well as against several pathogens including Gram-positive bacteria, Gram-negative bacteria, fungi and yeasts. Furthermore, they were tested for their cytotoxicity against two cancer cell lines L929 and KB-3-1. Compound 4 showed moderate inhibition of S. aureus biofilm formation with 30% and 25% at 256 and 128 μg/mL, respectively, while compounds 1 and 5 showed weak inhibition with 20% at 256 μg/mL. Compound 5 showed moderate cytotoxicity against both cell lines L929 and KB-3-1, with IC50 values of 18 μg/mL.

RevDate: 2020-03-26

Martinez S, Garcia JG, Williams R, et al (2020)

Lactobacilli spp.: real-time evaluation of biofilm growth.

BMC microbiology, 20(1):64 pii:10.1186/s12866-020-01753-3.

BACKGROUND: Biofilm is a fundamental bacterial survival mode which proceeds through three main generalized phases: adhesion, maturation, and dispersion. Lactobacilli spp. (LB) are critical components of gut and reproductive health and are widely used probiotics. Evaluation of time-dependent mechanisms of biofilm formation is important for understanding of host-microbial interaction and development of therapeutic interventions. Time-dependent LB biofilm growth was studied in two systems: large biofilm output in continuous flow system (microfermenter (M), Institute Pasteur, France) and electrical impedance-based real time label-free cell analyzer (C) (xCELLigence, ACEA Bioscience Inc., San Diego, CA). L. plantarum biofilm growth in M system was video-recorded, followed by analyses using IMARIS software (Bitplane, Oxford Instrument Company, Concord, MA, USA). Additionally, whole genome expression and analyses of attached (A) and dispersed (D) biofilm phases at 24 and 48 h were performed.

RESULTS: The dynamic of biofilm growth of L. plantarum was similar in both systems except for D phases. Comparison of the transcriptome of A and D phases revealed, that 121 transcripts differ between two phases at 24 h. and 35 transcripts - at 48 h. of M growth. The main pathways, down-regulated in A compared to D phases after 24 h. were transcriptional regulation, purine nucleotide biosynthesis, and L-aspartate biosynthesis, and the upregulated pathways were fatty acid and phospholipid metabolism as well as ABC transporters and purine nucleotide biosynthesis. Four LB species differed in the duration and amplitude of attachment phases, while growth phases were similar.

CONCLUSION: LB spp. biofilm growth and propagation area dynamic, time-dependent processes with species-specific and time specific characteristics. The dynamic of LB biofilm growth agrees with published pathophysiological data and points out that real time evaluation is an important tool in understanding growth of microbial communities.

RevDate: 2020-03-25

Mai Q, Cao J, Yang G, et al (2020)

Stratified Microbial Structure and Activity within Anode Biofilm during Electrochemically Assisted Brewery Wastewater Treatment.

Biotechnology and bioengineering [Epub ahead of print].

In a bioelectrochemical system (BES), microbial community of anode biofilm are crucial to BES performance. In this study, the stratified pattern of community structure and activity of an anode-respiring biofilm in a BES fueled with brewery wastewater was investigated over time. The anode biofilm exhibited a superior performance in the removal of ethanol to that of an open-circuit system. The electrical current density reached a high level of 0.55 mA/cm2 with a Coulombic efficiency of 71.4%, but decreased to 0.18 mA/cm2 in the late stage of operation. A mature biofilm developed a more active outer layer covering a less active inner core, although the activities of the outer and inner layers of biofilm were similar in the early stage. More Geobacter spp., typical exoelectrogens, were enriched in the outer layer than in the inner layer of biofilm in the early stage, while more Geobacter spp. were distributed in the outer layer than in the inner layer in the late stage. The inactive and Geobacter-occupied inner layer of biofilm might be responsible for the decreased electricity generation from wastewater in the late stage of operation. This study provides better understanding of the effect of anode biofilm structure on BES performance. This article is protected by copyright. All rights reserved.

RevDate: 2020-03-25

Zhang H, Bi Z, Pan Y, et al (2020)

Enhanced phosphorus storage in suspended biofilm by increasing dissolved oxygen.

The Science of the total environment, 722:137876 pii:S0048-9697(20)31389-9 [Epub ahead of print].

The phosphorus recovery efficiency in PAOs-biofilm system is so far limited to stimulating phosphorus release by adding concentrated organic carbon solution during the anaerobic stage. In present study, a PAOs-biofilm sequence batch reactor (BSBR) were operated to investigate whether increase of the phosphorus storage content via DO control can stimulate the release in the biofilm. During the operation of BSBR for 160 days, the phosphorus content in biofilm (Pbiofilm) was doubled via increasing dissolved oxygen (DO) from 4 to 6 mg/L. With the COD of 200 mg/L in the anaerobic phase, the phosphorus release was enhaced, resulting in an significant increase of phosphorus concentration from 94.85 to 179.5 mg/L in recirculated solution. Batch tests further clarified explicitly the increase of Pbiofilm stimulated a phosphorus release rate but this must be balanced since high Pbiofilm reduced the phosphorus removal capacity of the biofilm. With analysis of P31-NMR, Ortho-P and Poly-P were the main phosphorus species stored in biofilm. The microbial cell played a more important role than EPS in phosphorus storage. The dominant phylum in the master reactor was Proteobacteria with an abundance of 64.4%, in which the Rhodocyclaceae was the dominant PAOs with an abundance of 10.1%. The outcome of this study elucidated that increase of phosphorus storage via DO control which facilitated more efficient phosphorus release with much lower organic carbon source consumption during the enrichment of phosphorus. Meanwhile, we provided a new perspective for the recovery of phosphorus in future wastewater treatment plants.

RevDate: 2020-03-25

Kastl A, Bogler A, Spinnler M, et al (2020)

Impact of hydrodynamics on the first stages of biofilm formation in forward osmosis with spacers.

Environmental science & technology [Epub ahead of print].

Initial deposition of bacteria is a critical stage during biofilm formation and biofouling development in membrane systems used in the water industry. However, the effects of hydrodynamic conditions on spatiotemporal deposition patterns of bacteria during the initial stages of biofilm formation remain unclear. Large field epifluorescence microscopy enabled in situ and real-time tracking of Bacillus subtilis in a forward osmosis system with spacers during the first four hours of biofilm formation. This study quantitatively compares the spatiotemporal deposition patterns between different hydrodynamic conditions: high and low permeate water flux (6 or 30 L m-2 h-1) as well as high and low crossflow velocity (1 or 14 cm s 1). Low crossflow velocity and high permeate water flux maximized bacterial attachment to the membrane surface, which was 60 times greater (6 x 103 cells mm 2) than at high crossflow velocity and low permeate water flux (< 100 cells mm 2). Imaging at 30 s intervals revealed three phases (i.e., lag, exponential, and linear) in the development of deposition over time. Quantification of spatial deposition patterns showed that an increase in the ratio of permeate water flux to crossflow velocity led to a homogeneous deposition, while a decrease had the opposite effect. The insights of this research indicate that an appropriate choice of hydrodynamic conditions can minimize bacteria accumulation prior to biofilm formation in new and cleaned FO membrane systems treating water of high fouling propensity.

RevDate: 2020-03-24

Voss M, Alessio KO, Vianna Santos RC, et al (2020)

A Rapid, Non-Invasive, and Non-Destructive Method for Biofilm Imaging on Metallic Surfaces Using Active Thermography.

Analytical chemistry [Epub ahead of print].

A simple, rapid, low-cost method is proposed for the imaging of Pseudomonas aeruginosa biofilms on metallic surfaces using an infrared camera. Stainless steel coupons were cooled to generate a thermal gradient in relation to biofilm for active thermography (AT). Both cooling and image acquisition times were optimized and the images obtained with AT were compared with those from scanning electron microscopy. A free software (Thermofilm) was developed for image processing and the results were compared with the software ImageJ, with good agreement (from 87.7 to 103.8%). Images of coupons treated with sanitizer (peracetic acid) were obtained to show the applicability of the proposed method for biofilm studies. All analytical steps could be performed in 3 min in a non-contact, non-destructive, low-cost, portable, and easy-to-use way.

RevDate: 2020-03-24

Liu H, Liu X, N Ding (2020)

An Innovative in Situ Monitoring of Sulfate Reduction within a Wastewater Biofilm by H2S and SO42- Microsensors.

International journal of environmental research and public health, 17(6): pii:ijerph17062023.

Microelectrodes can be used to obtain chemical profiles within biofilm microenvironments. For example, sulfate (SO42-) and hydrogen sulfide (H2S) microelectrodes can be used to study sulfate reduction activity in this context. However, there is no SO42- microelectrode available for studying sulfate reduction in biofilms. In this study, SO42- and H2S microelectrodes were fabricated and applied in the measurement of a wastewater membrane-aerated biofilm (MAB) to investigate the in situ sulfate reduction activity. Both the SO42- and H2S microelectrodes with a tip diameter of around 20 micrometers were successfully developed and displayed satisfying selectivity to SO42- and H2S, respectively. The Nernstian slopes of calibration curves of the fabricated SO42- electrodes were close to -28.1 mV/decade, and the R2 values were greater than 98%. Within the selected concentration range from 10-5 M (0.96 mg/L) to 10-2 M (960 mg/L), the response of the SO42- microelectrode was log-linearly related to its concentration. The successfully fabricated SO42- microelectrode was combined with the existing H2S microelectrode and applied on an environmental wastewater biofilm sample to investigate the sulfate reduction activity within it. The H2S and SO42- microelectrodes showed stable responses and good performance, and the decrease of SO42- with an accompanying increased of H2S within the biofilm indicated the in situ sulfate reduction activity. The application of combined SO42- and H2S microelectrodes in wastewater biofilms could amend the current understanding of sulfate reduction and sulfur oxidation within environmental biofilms based on only H2S microelectrodes.

RevDate: 2020-03-23

Kamagata Y (2020)

Recent Biofilm Studies Open a New Door in Microbial Ecology.

Microbes and environments, 35(1):.

RevDate: 2020-03-21

Lu Z, Li D, Jiang L, et al (2020)

Characterizing the biofilm stoichiometry and kinetics on the media in situ based on pulse-flow respirometer coupling with a new breathing reactor.

Chemosphere, 252:126378 pii:S0045-6535(20)30571-3 [Epub ahead of print].

Biofilm based systems and the hybrid between activated sludge and biofilms have been popularly applied for wastewater treatment. Unlike the suspended biomass, the biofilm concentration and kinetics on the media cannot be easily measured. In this study, a novel and easy-to-use approach has been developed based on pulse-flow respirometer to characterize the biofilm stoichiometry and kinetics in situ. With the new designed breathing reactor, the mutual interference between the magnetic stirring and biofilm media that happened in the conventional breathing reactor was solved. Moreover, Microsoft Excel based programs had been developed to fit the oxygen uptake rate curves with dynamic nonlinear regression. With this new approach, the yield coefficient, maximum oxidation capacity, and half-saturation constant of substrate for the heterotrophic biofilms in a fix bed reactor were determined to be 0.46 g-VSS/g-COD, 67.0 mg-COD/(h·L-media), and 4.4 mg-COD/L, respectively. Those parameters for biofilm ammonia oxidizers from a moving bed biofilm reactor were determined to be 0.17 g-VSS/g-N, 18.6 mg-N/(h·L-media), and 1.2 mg-N/L, respectively, and they were 0.11 g-VSS/g-N, 20.9 mg-N/(h·L-media), and 0.98 mg-N/L for nitrite oxidizers in the same biofilms. This study also found that the maximum specific substrate utilization rate for detached biofilms increased by 3.2 times, indicating that maintaining biofilm integrity was very important in the kinetic tests. Using this approach, the biofilm kinetics on the media can be regularly measured for treatment optimization.

RevDate: 2020-03-21

Muthamil S, Prasath KG, Priya A, et al (2020)

Global proteomic analysis deciphers the mechanism of action of plant derived oleic acid against Candida albicans virulence and biofilm formation.

Scientific reports, 10(1):5113 pii:10.1038/s41598-020-61918-y.

Candida albicans is a commensal fungus in humans, mostly found on the mucosal surfaces of the mouth, gut, vagina and skin. Incidence of ever increasing invasive candidiasis in immunocompromised patients, alarming occurrence of antifungal resistance and insufficient diagnostic methods demand more focused research into C. albicans pathogenicity. Consequently, in the present study, oleic acid from Murraya koenigii was shown to have the efficacy to inhibit biofilm formation and virulence of Candida spp. Results of in vitro virulence assays and gene expression analysis, impelled to study the protein targets which are involved in the molecular pathways of C. albicans pathogenicity. Proteomic studies of differentially expressed proteins reveals that oleic acid induces oxidative stress responses and mainly targets the proteins involved in glucose metabolism, ergosterol biosynthesis, lipase production, iron homeostasis and amino acid biosynthesis. The current study emphasizes anti-virulent potential of oleic acid which can be used as a therapeutic agent to treat Candida infections.

RevDate: 2020-03-20

Peruč D, Tićac B, Broznić D, et al (2020)

Juniperus communis essential oil limit the biofilm formation of Mycobacterium avium and Mycobacterium intracellulare on polystyrene in a temperature-dependent manner.

International journal of environmental health research [Epub ahead of print].

Formation of biofilms allows bacterial cells to survive in adverse environments. Nontuberculous mycobacteria are ubiquitous in aqueous environments, where they adhere to surfaces and create a biofilm. This has led to the emergence of healthcare-associated infections and the use of biomaterials in medicine. Essential oils (EO) are substances of natural origin whose effect on microorganisms has been the subject of numerous studies. Here, we investigated the effect of Juniperus communis EO on nontuberculous mycobacteria and their early and mature biofilm formation in sterilised tap water. The combination of Juniperus communis EO and increasing ambient temperature showed a synergistic effect on the reduction of biofilm formation of Mycobacterium avium and Mycobacterium intracellulare on a polystyrene surface. A significant antibiofilm effect of Juniperus communis EO was also found at subinhibitory concentrations, suggesting a potential role for it as an alternative disinfectant of natural water.

RevDate: 2020-03-20

Alhede M, Alhede M, Qvortrup K, et al (2020)

The origin of extracellular DNA in bacterial biofilm infections in vivo.

Pathogens and disease pii:5810662 [Epub ahead of print].

Extracellular DNA (eDNA) plays an important role in both the aggregation of bacteria and in the interaction of the resulting biofilms with polymorphonuclear leukocytes (PMNs) during an inflammatory response. Here, transmission electron and confocal scanning laser microscopy were used to examine the interaction between biofilms of Pseudomonas aeruginosa and PMNs in a murine implant model and in lung tissue from chronically infected cystic fibrosis patients. PNA FISH, DNA staining, labeling of PMN DNA with a thymidine analogue, and immunohistochemistry were applied to localize bacteria, eDNA, PMN-derived eDNA, PMN-derived histone H3 (H3), neutrophil elastase (NE), and citrullinated H3 (citH3). Host-derived eDNA was observed surrounding bacterial biofilms but not within the biofilms. H3 localized to the lining of biofilms while NE was found throughout biofilms. CitH3, a marker for neutrophil extracellular traps (NETs) was detected only sporadically indicating that most host-derived eDNA in vivo was not a result of NETosis. Together these observations show that, in these in vivo biofilm infections with P. aeruginosa, the majority of eDNA is found external to the biofilm and derives from the host.

RevDate: 2020-03-20

Ferlic PW, Liebensteiner M, Nogler M, et al (2020)

Increased Staphylococcus aureus Biofilm Formation on Biodegradable Poly(3-Hydroxybutyrate)-Implants Compared with Conventional Orthopedic Implants: An In Vitro Analysis.

Journal of orthopaedic trauma, 34(4):210-215.

OBJECTIVE: To compare the biofilm formation on a biodegradable material, poly(3-hydroxybutyrate) (PHB), with that on conventional titanium (Ti) and steel (St) implant material.

METHODS: Pins made of the different materials were incubated in Müller-Hinton broth inoculated with 2 × 10 colony-forming units (CFU)·mL of Staphylococcus aureus for 2 and 7 days and then sonicated for the disruption of the biofilms. CFU were counted to quantify the number of bacteria in the biofilm, and the cell proliferation assay 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H- tetrazolium-5-carboxanilid salt was used to evaluate their metabolic activity. Scanning electron microscopy visualized the structure of the biofilm.

RESULTS: We found a significantly higher metabolic activity and CFU count in the biofilm of PHB pins compared with St and Ti pins (analysis of variance, P < 0.0001). Scanning electron microscopy revealed structured biofilms on PHB pins already after 2 days of incubation, which was not observed on the other tested implants.

CONCLUSION: PHB implants seem to provide an environment that advantages the formation of biofilms of S. aureus, a common pathogen in implant-related infections. The amount of biofilm is higher on PHB implant compared with conventionally used orthopedic titanium and steel implants. To overcome the potential risk of surgical site infections linked to the clinical use of PHB implants, possible modifications of the material, increasing its antibacterial properties, need to be further investigated.

RevDate: 2020-03-20

Tosato MG, Schilardi P, Lorenzo de Mele MF, et al (2020)

Synergistic effect of carboxypterin and methylene blue applied to antimicrobial photodynamic therapy against mature biofilm of Klebsiella pneumoniae.

Heliyon, 6(3):e03522 pii:e03522.

The control of multidrug-resistant (MDR) bacteria is a growing public health problem, and new strategies are urgently needed for the control of the infections caused by these microorganisms. Notoriously, some MDR microorganisms generate complex structures or biofilms, which adhere to surfaces and confer extraordinary resistance properties that are fundamental challenges to control infections. One of the promising strategies for the control of MDR bacteria is antimicrobial photodynamic therapy (aPDT), which takes advantage of suitable photosensitizers (PS), oxygen and radiation to eradicate microorganisms by the generation of highly reactive species, including reactive oxygen species (ROS) that cause cytotoxic damage and cell death. Habitual aPDT treatments use only methylene blue (MB), but MDR microorganism eradication is not completely achieved. The key result of this study revealed that a combination of two known PSs, 6-carboxypterin (Cap, 100 μM) and MB (2.5-10 μM) exposed to ultraviolet and visible radiation, presents a synergistic effect on the eradication of a MDR Klebsiella pneumoniae strain. Similar effect was observed when the treatment was performed either with planktonic or biofilm growing cells. Moreover, it was found that after treatment the killing action continues in the absence of irradiation leading to the eradication of the microorganisms growing in biofilm. Therefore, the combined aPDT represents a promising strategy for the management of clinical contact surfaces, disinfection of surgical instruments, biofouling and even antimicrobial wastewater treatment.

RevDate: 2020-03-20

Rodriguez-Nava G, Mohamed A, Yanez-Bello MA, et al (2020)

Advances in medicine and positive natural selection: Prosthetic valve endocarditis due to biofilm producer Micrococcus luteus.

IDCases, 20:e00743 pii:e00743.

Over the past years there has been a considerable increase in the use of aortic bioprostheses for treating aortic valve disease. With the increasing use of implanted medical devices, the incidence of prosthetic valve endocarditis has also increased. This is accompanied by a shift in the microbiology of infectious endocarditis. Micrococcus species are usually regarded as contaminants from skin and mucous membranes that rarely cause infectious diseases, however, they have the capacity to create biofilms from prosthetic materials and hence, to cause disease. We report the case of a 54-year-old woman who developed native valve infective endocarditis due to Micrococcus luteus. To our knowledge, only 18 cases of M. luteus prosthetic valve endocarditis have been described, none in the English literature.

RevDate: 2020-03-20

Qi R, Zhang N, Zhang P, et al (2020)

Gemini Peptide Amphiphiles with Broad-spectrum Antimicrobial Activity and Potent Anti-biofilm Capacity.

ACS applied materials & interfaces [Epub ahead of print].

To address the challenge from microbial resistance and biofilm, this work develops three gemini peptide amphiphiles with basic tetrapeptides spacer 12-(Arg)4-12, 12-(Lys)4-12 and 12-(His)4-12, and finds they exhibit varied antimicrobial/anti-biofilm activities. 12-(Arg)4-12 shows the best performance, possessing the broad-spectrum antimicrobial activity and excellent anti-biofilm capacity. The antimicrobial and anti-biofilm activities strongly depend on the membrane permeation and self-assembling structure of these peptide amphiphiles. Gemini peptide amphiphile with highly polar arginine as spacer, 12-(Arg)4-12, self-assembles into short rods which are prone to dissociate into monomers to permeate and lysis membrane, leading to its broad-spectrum antimicrobial activity and high efficiency in eradicating biofilm. Long rods formed by relatively weaker polar 12-(Lys)4-12 are less prone to disassemble into monomers for further membrane permeation, which make it selectively kill more negatively charged bacteria and endow it medium anti-biofilm activity. Low polar 12-(His)4-12 aggregates into long fibers which are very difficult to dissociate and they mainly electrostatically bind on the negative microbial surface, resulting in its weakest antimicrobial and anti-biofilm activity. This study reveals the effect of antimicrobial peptide structure and aggregation on the antimicrobial activities, and would be helpful for developing high-efficient antimicrobial peptides with anti-biofilm activity.

RevDate: 2020-03-20

Gutiérrez-Almada K, González-Acosta B, Borges-Souza JM, et al (2020)

Marine bacteria associated with shallow hydrothermal systems in the Gulf of California with the capacity to produce biofilm inhibiting compounds.

Archives of microbiology pii:10.1007/s00203-020-01851-w [Epub ahead of print].

Shallow hydrothermal systems are extreme environments. The sediments and fluids emitted from the vents present unusual physical and chemical conditions compared to other marine areas, which promotes unique biodiversity that has been of great interest for biotechnology for some years. In this work, a bioprospective study was carried out to evaluate the capacity of bacteria associated with shallow hydrothermal vents to produce biofilm-inhibiting compounds. Degradation assays of N-acyl homoserine lactone (AHL) autoinducers (C6HSL) involved in the quorum sensing process were carried out on 161 strains of bacteria isolated from three shallow hydrothermal systems located in Baja California Sur (BCS), Mexico. The biosensor Chromobacterium violaceum CV026 was used. Twenty-three strains showed activity, and organic extracts were obtained with ethyl acetate. The potential of the extracts to inhibit the formation of biofilms was tested against two human pathogenic strains (Pseudomonas aeruginosa PAO1 and Aeromonas caviae ScH3), a shrimp pathogen (Vibrio parahaemolyticus M8), and two marine strains identified as producing biofilms on submerged surfaces (Virgibacillus sp C29 and Vibrio alginolyticus C96). The results showed that Vibrio alginolyticus and Brevibacillus thermoruber, as well as some thermotolerant strains (mostly Bacillus), produce compounds that inhibit bacterial biofilms (B. licheniformis, B. paralicheniformis, B. firmus, B. oceanizedimenis, B. aerius and B. sonorensis).

RevDate: 2020-03-20

Greener J (2019)

On the nature of "skeletal" biofilm patterns, "hidden" heterogeneity and the role of bubbles to reveal them.

NPJ biofilms and microbiomes, 5(1):12 pii:10.1038/s41522-019-0085-6.

A short communication on the recent paper by Jang et al. discusses the role of "mushroom" structures and effects of nearly static bubbles on nascent biofilms.

RevDate: 2020-03-20

Fei C, Mao S, Yan J, et al (2020)

Nonuniform growth and surface friction determine bacterial biofilm morphology on soft substrates.

Proceedings of the National Academy of Sciences of the United States of America pii:1919607117 [Epub ahead of print].

During development, organisms acquire three-dimensional (3D) shapes with important physiological consequences. While basic mechanisms underlying morphogenesis are known in eukaryotes, it is often difficult to manipulate them in vivo. To circumvent this issue, here we present a study of developing Vibrio cholerae biofilms grown on agar substrates in which the spatiotemporal morphological patterns were altered by varying the agar concentration. Expanding biofilms are initially flat but later undergo a mechanical instability and become wrinkled. To gain mechanistic insights into this dynamic pattern-formation process, we developed a model that considers diffusion of nutrients and their uptake by bacteria, bacterial growth/biofilm matrix production, mechanical deformation of both the biofilm and the substrate, and the friction between them. Our model shows quantitative agreement with experimental measurements of biofilm expansion dynamics, and it accurately predicts two distinct spatiotemporal patterns observed in the experiments-the wrinkles initially appear either in the peripheral region and propagate inward (soft substrate/low friction) or in the central region and propagate outward (stiff substrate/high friction). Our results, which establish that nonuniform growth and friction are fundamental determinants of stress anisotropy and hence biofilm morphology, are broadly applicable to bacterial biofilms with similar morphologies and also provide insight into how other bacterial biofilms form distinct wrinkle patterns. We discuss the implications of forming undulated biofilm morphologies, which may enhance the availability of nutrients and signaling molecules and serve as a "bet hedging" strategy.

RevDate: 2020-03-20

Jiang H, Peng Y, Li X, et al (2020)

Advanced nitrogen removal from mature landfill leachate via partial nitrification-Anammox biofilm reactor (PNABR) driven by high dissolved oxygen (DO): Protection mechanism of aerobic biofilm.

Bioresource technology, 306:123119 pii:S0960-8524(20)30390-4 [Epub ahead of print].

A novel partial nitrification-Anammox biofilm reactor (PNABR) operated under high dissolved oxygen (DO) with pre-anoxic - aerobic - anoxic operational mode was developed for efficient denitrogenation from mature landfill leachate. With DO concentration gradually increasing to 4.03 ± 0.03 mg/L, the ammonia oxidation rate (AOR) was enhanced to 25.8 mgNH4+-N/(L h), while nitrite oxidation bacteria (NOB) was inhibited effectively by alternating free ammonia (FA) and oxygen starvation. DO micro-distribution revealed that estimated 1900 μm of aerobic biofilm could protect anammox biofilm underneath from being inhibited by high DO. qPCR analysis further suggested that ammonia oxidation bacteria (AOB) abundance in whole biofilm was 6.12 × 109 gene copies/(g dry sludge), which was twice than found in the floc. Anammox bacteria accounted for 2.39% of total bacteria in whole biofilm, contributing 90.0% to nitrogen removal. Nitrogen removal rate (NRR) and nitrogen removal efficiency (NRE) finally reached 396.6 gN/(m3 d) and 96.1%, respectively.

RevDate: 2020-03-20

Swain G, Sonwani RK, Giri BS, et al (2020)

Collective removal of phenol and ammonia in a moving bed biofilm reactor using modified bio-carriers: Process optimization and kinetic study.

Bioresource technology, 306:123177 pii:S0960-8524(20)30448-X [Epub ahead of print].

The performance of a moving bed biofilm reactor (MBBR) with bio-carriers made of polypropylene-polyurethane foam (PP-PUF) was evaluated for the collective removal of phenol and ammonia. Three independent variables, including pH (5.0-8.0), retention time (2.0-12.0 h), and airflow rate (0.8-3.5 L/min) were optimized using central composite design (CCD) of response surface methodology (RSM). The maximum removal of phenol and ammonia was obtained to be 92.6, and 91.8%, respectively, in addition to the removal of 72.3% in the chemical oxygen demand (COD) level at optimum conditions. First-order and second-order kinetic models were analyzed to evaluate the pollutants removal kinetics in a MBBR. Finally, a second-order model was found to be appropriate for predicting reaction kinetics. The values of second-order rate constants were obtained to be 2.35, 0.25, and 1.85 L2/gVSS gCOD h for phenol, COD, and ammonia removal, respectively.

RevDate: 2020-03-20

Alibi S, Ben Selma W, Ramos-Vivas J, et al (2020)

Anti-oxidant, antibacterial, anti-biofilm, and anti-quorum sensing activities of four essential oils against multidrug-resistant bacterial clinical isolates.

Current research in translational medicine pii:S2452-3186(20)30018-0 [Epub ahead of print].

PURPOSE OF THE STUDY: Outbreaks of multidrug-resistant bacteria are increasingly reported at the clinical setting. The antimicrobial, anti-biofilm, anti-quorum sensing, and anti-oxidant activities of four essential oils extracted from Cinnamomum verum, Origanum majorana, Thymus vulgaris, and Eugenia caryophyllata against Gram-positive and Gram-negative multidrug-resistant bacteria were evaluated in vitro.

MATERIALS AND METHODS: This study was conducted on 105 multidrug resistant clinical strains. Inhibition diameter zone, minimum inhibitory concentration, and minimum bactericide concentration of the oils were determined using agar disc diffusion method and microdilution. The ability of the 4 essential oils to inhibit the production of bacterial biofilms was tested on polystyrene plates, as well as their inhibitory effect on the production of violacein by Chromobacterium violaceum CV026. The anti-oxidant activity was evaluated by the 2,2-diphenyl-1-picrylhydrazyl scavenging method.

RESULTS: Essential oils of Cinnamomum verum, Thymus vulgaris and Eugenia caryophyllata showed an important antibacterial activity. The inhibition diameter zone was higher than 20 mm for 90.24 %, 85.71 % and 60.95 % of strains respectively. These essential oils have a remarkable anti-biofilm and anti-quorum sensing activities against almost all the species studied. Clove extract revealed the highest anti-oxidant activity (Pourcentage of inhibtion of DPPH = 90.3 %).

CONCLUSION: These results supported the use of the 4 essential oils as alternative or complementary agents to treat infections caused by multidrug-resistant bacteria, and to prevent biofilm formation and quorum sensing signaling. They might be used as a safe anti-oxidants instead of harmful artificial ones.

RevDate: 2020-03-20

Tran P, Enos T, Luth K, et al (2020)

Organo-Selenium-Containing Polyester Bandage Inhibits Bacterial Biofilm Growth on the Bandage and in the Wound.

Biomedicines, 8(3): pii:biomedicines8030062.

The dressing material of a wound plays a key role since bacteria can live in the bandage and keep re-infecting the wound, thus a bandage is needed that blocks biofilm in the bandage. Using an in vivo wound biofilm model, we examined the effectiveness of an organo-selenium (OS)-coated polyester dressing to inhibit the growth of bacteria in a wound. Staphylococcus aureus (as well as MRSA, Methicillin resistant Staph aureus), Stenotrophomonas maltophilia, Enterococcus faecalis, Staphylococcus epidermidis, and Pseudomonas aeruginosa were chosen for the wound infection study. All the bacteria were enumerated in the wound dressing and in the wound tissue under the dressing. Using colony-forming unit (CFU) assays, over 7 logs of inhibition (100%) was found for all the bacterial strains on the material of the OS-coated wound dressing and in the tissue under that dressing. Confocal laser scanning microscopy along with IVIS spectrum in vivo imaging confirmed the CFU results. Thus, the dressing acts as a reservoir for a biofilm, which causes wound infection. The same results were obtained after soaking the dressing in PBS at 37 °C for three months before use. These results suggest that an OS coating on polyester dressing is both effective and durable in blocking wound infection.

RevDate: 2020-03-19

Liu L, Yu B, Sun W, et al (2020)

Calcineurin signaling pathway influences Aspergillus niger biofilm formation by affecting hydrophobicity and cell wall integrity.

Biotechnology for biofuels, 13:54 pii:1692.

Background: Biofilms, as a kind of fixed-cell community, can greatly improve industrial fermentation efficiency in immobilized fermentation, but the regulation process is still unclear, which restricts their application. Ca2+ was reported to be a key factor affecting biofilm formation. However, the effect of Ca2+ on biofilm structure and microbiology was yet only studied in bacteria. How Ca2+-mediated calcineurin signaling pathway (CSP) alters biofilm formation in bacteria and fungi has rarely been reported. On this basis, we investigated the regulation of CSP on the formation of biofilm in Aspergillus niger.

Results: Deletion of the key genes MidA, CchA, CrzA or CnaA in the CSP lowered the Ca2+ concentration in the mycelium to a different extent, inhibited the formation of A. niger biofilm, reduced the hydrophobicity and adhesion of spores, destroyed the cell wall integrity of hyphae, and reduced the flocculation ability of hyphae. qRT-PCR results showed that the expression of spore hydrophobic protein RodA, galactosaminogalactan (GAG) biosynthesis genes (uge3, uge5, agd3, gtb3), and α-1,3-glucan biosynthesis genes (ags1, ags3) in the ∆MidA, ∆CchA, ∆CrzA, ∆CnaA strains were significantly down-regulated compared with those of the wild type (WT). In addition, the transcription levels of the chitin synthesis gene (chsB, chsD) and β-1,3-glucan synthesis gene (FksA) were consistent with the change in chitin and β-1,3-glucan contents in mutant strains.

Conclusion: These results indicated that CSP affected the hydrophobicity and adhesion of spores, the integrity of mycelial cell walls and flocculation by affecting Ca2+ levels in mycelium, which in turn affected biofilm formation. This work provides a possible explanation for how CSP changes the formation of A. niger biofilm, and reveals a pathway for controlling biofilm formation in industrial immobilized fermentation.

RevDate: 2020-03-19

Li Y, Wang Y, Chen X, et al (2020)

Antimicrobial peptide GH12 as root canal irrigant inhibits biofilm and virulence of Enterococcus faecalis.

International endodontic journal [Epub ahead of print].

AIM: The objectives of this laboratory-based study were to investigate the effects of GH12 on E. faecalis biofilm and virulence.

METHODOLOGY: Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of GH12 against E. faecalis were first determined. Time-kill assay was further conducted. The effects of GH12 on the expression of virulence and stress genes in E. faecalis were evaluated by RT-qPCR. Crystal violet stain was used to investigate the effects of GH12 on E. faecalis biofilm formation and 1-day-old biofilm. Finally, an ex vivo tooth model contaminated with E. faecalis was used to evaluate the antimicrobial activity of GH12 as an irrigant by CFU counting, SEM and CLSM. One-way ANOVA and Tukey's multiple comparisons test were used to compare the differences among groups (α = 0.05).

RESULTS: The MICs and MBCs of GH12 against E. faecalis were 8.0 ± 0.0 mg/L and 16.0 ± 0.0 mg/L, respectively and GH12 at 32.0 mg/L reduced the bacterial numbers by more than 99.9% within 1 min. Various virulence genes (efaA, esp, gelE) and stress genes (dnaK, groEL, ctsR, clpPBCEX) in E. faecalis were significantly downregulated by GH12 at sub-MIC levels (P < 0.05). Additionally, both E. faecalis biofilm formation and the biomass of 1-day-old E. faecalis biofilms were significantly reduced by GH12 (P < 0.05). Elimination of E. faecalis in biofilms from root canal walls was achieved through irrigation with 64.0 mg/L GH12 for 30 min. CLSM analysis revealed that GH12 at 64.0 mg/L was most effective in eliminating bacteria within dentinal tubules (P < 0.05).

CONCLUSION: In a laboratory setting, and when used as an irrigant, GH12 suppressed E. faecalis, downregulated specific virulence and stress-associated genes, eliminated intracanal E. faecalis protected by biofilms and killed bacteria in dentinal tubules. These results emphasise the need for preclinical and clinical studies to explore the potential of GH12 as an antimicrobial agent in root canal treatment.

RevDate: 2020-03-19

Labena A, Hegazy MA, Sami RM, et al (2020)

Multiple Applications of a Novel Cationic Gemini Surfactant: Anti-Microbial, Anti-Biofilm, Biocide, Salinity Corrosion Inhibitor, and Biofilm Dispersion (Part II).

Molecules (Basel, Switzerland), 25(6): pii:molecules25061348.

The Egyptian petroleum industries are incurring severe problems with corrosion, particularly corrosion that is induced by sulfidogenic microbial activities in harsh salinity environments despite extensively using biocides and metal corrosion inhibitors. Therefore, in this study, a synthesized cationic gemini surfactant (SCGS) was tested as a broad-spectrum antimicrobial, anti-bacterial, anti-candida, anti-fungal, anti-biofilm (anti-adhesive), and bio-dispersion agent. The SCGS was evaluated as a biocide against environmental sulfidogenic-bacteria and as a corrosion inhibitor for a high salinity cultivated medium. The SCGS displayed wide spectrum antimicrobial activity with minimum bactericidal/fungicidal inhibitory concentrations. The SCGS demonstrated anti-bacterial, anti-biofilm, and bio-dispersion activity. The SCGS exhibited bactericidal activity against environmental sulfidogenic bacteria and the highest corrosion inhibition efficiency of 93.8% at 5 mM. Additionally, the SCGS demonstrated bio-dispersion activity against the environmental sulfidogenic bacteria at 5.49% salinity. In conclusion, this study provides a novel synthesized cationic surfactant with many applications in the oil and gas industry: as broad-spectrum antimicrobial and anti-biofilm agents, corrosion inhibition for high salinity, biocides for environmentally sulfidogenic bacteria, and as bio-dispersion agents.


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.


Order from Amazon

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 )