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Bibliography on: Archaea

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ESP: PubMed Auto Bibliography 18 Sep 2020 at 01:30 Created: 

Archaea

In 1977, Carl Woese and George Fox applied molecular techniques to biodiversity and discovered that life on Earth consisted of three, not two (prokaryotes and eukaryotes), major lineages, tracing back nearly to the very origin of life on Earth. The third lineage has come to be known as the Archaea. Organisms now considered Archaea were originally thought to be a kind of prokaryote, but Woese and Fox showed that they were as different from prokaryotes as they were from eukaryotes. To understand life on Earth one must also understand the Archaea .

Created with PubMed® Query: archaea[TITLE] OR archaebacteria[TITLE] NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

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RevDate: 2020-09-16

Yin XM, Yang XY, Hou J, et al (2020)

Natronomonas halophila sp. nov. and Natronomonas salina sp. nov., two novel halophilic archaea.

International journal of systematic and evolutionary microbiology [Epub ahead of print].

Two halophilic archaeal strains, C90T and YPL13T, were isolated from a salt lake and a salt mine in PR China. The two strains were found to form two clusters (97.5 and 89.5 % similarity between them, respectively) separating them from the three current members of the genus Natronomonas (95.4-97.0 % and 86.6-89.3 % similarity, respectively) on the basis of the 16S rRNA and rpoB' gene sequence similarities and phylogenetic analysis. Diverse phenotypic characteristics differentiate strains C90T and YPL13T from current Natronomonas members. The polar lipids of strain C90T were phosphatidic acid, phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulphate, two unidentified glycolipids, a major glycolipid and a minor glycolipid, while those of strain YPL13T were PG, PGP-Me, two unidentified phospholipids and a glycolipid. The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between the two strains were 79.8 and 27.1 %, respectively, which were much lower than the threshold values proposed as a species boundaries (ANI 95-96 % and isDDH 70 %), which revealed that the two strains represent two novel species; these values (ANI 76.6-80.0 % and isDDH 21.6-27.0 %) of the strains examined in this study and the current members of Natronomonas are much lower than the recommended threshold values, suggesting that strains C90T and YPL13T represent two genomically different species of Natronomonas. These results showed that strains C90T (=CGMCC 1.13738T=JCM 32961T) and YPL13T (=CGMCC 1.13884T=JCM 31111T) represent two novel species of Natronomonas, for which the names Natronomonas halophila sp. nov. and Natronomonas salina sp. nov. are proposed.

RevDate: 2020-09-16

He Y, Zhou Y, Weng R, et al (2020)

Responses of Ammonia-Oxidizing Archaea and Bacteria in Malodorous River Sediments to Different Remediation Techniques.

Microbial ecology pii:10.1007/s00248-020-01597-4 [Epub ahead of print].

In this study, the joint use of high throughput sequencing, real-time quantitative PCR, and ammonia-oxidizing bacteria (AOB)-inhibiting allylthiourea was used to differentiate between the contributions of ammonia-oxidizing archaea (AOA) vs AOB to ammonia oxidation and ascertain how AOA and AOB responded to two widely used river remediation techniques (aeration and Ca(NO3)2 injection). Results showed that ammonia oxidation was largely attributed to ATU-sensitive AOB rather than AOA and Nitrosomonas was the predominant AOB-related genus (53.86%) in the malodorous river. The contribution of AOB to ammonia oxidation in the context of aeration and Ca(NO3)2 injection was 75.51 ± 2.77% and 60.19 ± 10.44%, respectively. The peak of AOB/AOA ratio and the marked increase of relative abundances of Nitrosomonas and Nitrosospira in aeration runs further demonstrated aeration favored the ammonia oxidation of AOB. Comparatively, Ca(NO3)2 injection could increase the ammonia oxidation contribution of AOA from 31.32 ± 6.06 to 39.81 ± 10.44% and was significantly correlated with Nitrosococcus of AOB (r = 0.796, p < 0.05), Candidatus_Nitrosopelagicus of AOA (r = 0.986, p < 0.01), and AOA Simpson diversity (r = - 0.791, p < 0.05). Moreover, Candidatus_Nitrosopelagicus was only present in Ca(NO3)2 runs. Taken together, Ca(NO3)2 was recognized as an important factor in mediating the growth and ecological niches of ammonia oxidizers.Graphical abstract.

RevDate: 2020-09-14

Aleksandrowicz P, Brzezińska-Błaszczyk E, Dudko A, et al (2020)

Archaea Occurrence in the Subgingival Biofilm in Patients with Peri-implantitis and Periodontitis.

The International journal of periodontics & restorative dentistry, 40(5):677-683.

This study aimed to determine the prevalence and diversity of archaea and select bacteria in the subgingival biofilm of patients with peri-implantitis in comparison to patients with unaffected implants and patients with periodontitis. Samples of subgingival biofilm from oral sites were collected for DNA extraction (n = 139). A 16S rRNA gene-based polymerase chain reaction assay was used to determine the presence of archaea and select bacteria. Seven samples were selected for direct sequencing. Archaea were detected in 10% of samples from peri-implantitis sites, but not in samples from the unaffected dental implant. Archaea were present in 53% and 64% of samples from mild and moderate/advanced periodontitis sites, respectively. The main representative of the Archaea domain found in biofilm from periodontitis and peri-implantitis sites was Methanobrevibacter oralis. The present results revealed that archaea are present in diseased but not healthy implants. It was also found that archaea were more abundant in periodontitis than in peri-implantitis sites. Hence, the potential role of archaea in peri-implantitis and periodontitis should be taken into consideration.

RevDate: 2020-09-12

Di Giulio M (2020)

LUCA as well as the ancestors of archaea, bacteria and eukaryotes were progenotes: Inference from the distribution and diversity of the reading mechanism of the AUA and AUG codons in the domains of life.

Bio Systems pii:S0303-2647(20)30128-3 [Epub ahead of print].

Here I use the rationale assuming that if of a certain trait that exerts its function in some aspect of the genetic code or, more generally, in protein synthesis, it is possible to identify the evolutionary stage of its origin then it would imply that this evolutionary moment would be characterized by a high translational noise because this trait would originate for the first time during that evolutionary stage. That is to say, if this trait had a non-marginal role in the realization of the genetic code, or in protein synthesis, then the origin of this trait would imply that, more generally, it was the genetic code itself that was still originating. But if the genetic code were still originating - at that precise evolutionary stage - then this would imply that there was a high translational noise which in turn would imply that it was in the presence of a protocell, i.e. a progenote that was by definition characterized by high translational noise. I apply this rationale to the mechanism of modification of the base 34 of the anticodon of an isoleucine tRNA that leads to the reading of AUA and AUG codons in archaea, bacteria and eukaryotes. The phylogenetic distribution of this mechanism in these phyletic lineages indicates that this mechanism originated only after the evolutionary stage of the last universal common ancestor (LUCA), namely, during the formation of cellular domains, i.e., at the stage of ancestors of these main phyletic lineages. Furthermore, given that this mechanism of modification of the base 34 of the anticodon of the isoleucine tRNA would result to emerge at a stage of the origin of the genetic code - despite in its terminal phases - then all this would imply that the ancestors of bacteria, archaea and eukaryotes were progenotes. If so, all the more so, the LUCA would also be a progenote since it preceded these ancestors temporally. A consequence of all this reasoning might be that since these three ancestors were of the progenotes that were different from each other, if at least one of them had evolved into at least two real and different cells - basically different from each other - then the number of cellular domains would not be three but it would be greater than three.

RevDate: 2020-09-06

Qi L, Ma Z, Chang SX, et al (2020)

Biochar decreases methanogenic archaea abundance and methane emissions in a flooded paddy soil.

The Science of the total environment, 752:141958 pii:S0048-9697(20)35487-5 [Epub ahead of print].

Biochar addition can reduce methane (CH4) emissions from paddy soils while the mechanisms involved are not entirely clear. Here, we studied the effect of biochar addition on CH4 emissions, and the abundance and community composition of methanogens and methanotrophs over two rice cultivation seasons. The experiment had the following five treatments: control (CK), chemical fertilizer application only (BC0), and 0.5% (w/w) (BC1), 1% (BC2), and 2% of biochar applied with chemical fertilizers (BC3). The season-wide CH4 emissions were decreased (P < 0.05) by 22.2-95.7% in biochar application compared with BC0 in the two rice seasons (2017 and 2018). In 2017, biochar application decreased methanogenic archaea (mcrA) but increased methanotrophic bacteria (pmoA) abundances, and decreased the ratio of mcrA/pmoA, as compared with BC0 (P < 0.05). In 2018, the abundance of mcrA was lower in BC2 and BC3 than in BC0 (P < 0.05) but was not different between BC0 and BC1, and the abundance of pmoA was lower in BC1, BC2 and BC3 than in BC0 (P < 0.05). The CH4 emissions were positively related to abundances of the mcrA gene (P < 0.01) but not to that of the pmoA gene in two rice seasons. Rice grain yield was increased by 62.2-94.1% in biochar addition treatments compared with BC0 in the first year (P < 0.01) and by 29.9-37.6% in BC2 and BC3 compared with BC0 in the second year (P < 0.05). Biochar application decreased CH4 emissions by reducing methanogenic archaea abundance in the studied flooded paddy soil.

RevDate: 2020-09-06

Niu M, Zhou F, Yang Y, et al (2020)

Abundance and composition of airborne archaea during springtime mixed dust and haze periods in Beijing, China.

The Science of the total environment, 752:141641 pii:S0048-9697(20)35170-6 [Epub ahead of print].

Archaea have an important role in the elemental biogeochemical cycle and human health. However, characteristics of airborne archaea affected by anthropogenic and natural processes are unclear. In this study, we investigated the abundance, structures, influencing factors and assembly processes of the archaeal communities in the air samples collected from Beijing in springtime using quantitative polymerase chain reaction (qPCR), high-throughput sequencing technology and statistical analysis. The concentrations of airborne archaea ranged from 101 to 103 copies m-3 (455 ± 211 copies m-3), accounting for 0.67% of the total prokaryote (sum of archaea and bacteria). An increase in airborne archaea was seen when the air quality shifted from clean to slightly polluted conditions. Sandstorm dust imported a large number of archaea to the local atmosphere. Euryarchaeota, Thaumarchaeota and Crenarchaeota were the dominant phyla, revealing the primary role of soil in releasing archaea to the ambient environment. Dispersal-related neutral processes play an important role in shaping the structure of airborne archaeal assembly. Of all phyla, methanogenic Euryarchaeota were most abundant in the air parcels come from the south of Beijing. Air masses from the west of Beijing, which brought sandstorm to Beijing, carried large amounts of ammonia oxidizing archaea Nitrososphaera. The results demonstrate the importance of air mass sources and local weather conditions in shaping the local airborne archaea community.

RevDate: 2020-09-05

Nikolayev S, Cohen-Rosenzweig C, J Eichler (2020)

Evolutionary considerations of the oligosaccharyltransferase AglB and other aspects of N-glycosylation across Archaea.

Molecular phylogenetics and evolution pii:S1055-7903(20)30223-2 [Epub ahead of print].

Various biological markers in members of the TACK and Asgard archaeal super-phyla show Eukarya-like traits. These include the oligosaccharyltransferase, responsible for transferring glycans from the lipid carrier upon which they are assembled onto selected asparagine residues of target proteins during N-glycosylation. In Archaea, oligosaccharyltransferase activity is catalyzed by AglB. To gain deeper insight into AglB and N-glycosylation across archaeal phylogeny, bioinformatics approaches were employed to address variability in AglB sequence motifs involved in enzyme activity, construct a phylogenetic tree based on AglB sequences, search for archaeal homologues of non-catalytic subunits of the multimeric eukaryal oligosaccharyltransferase complex and predict the presence of aglB-based clusters of glycosylation-related genes in the Euryarchaeota and the DPANN, TACK and Asgard super-phyla. In addition, site-directed mutagenesis and mass spectrometry were employed to study the natural variability in the WWDXG motif central to oligosaccharyltransferase activity seen in archaeal AglB. The results clearly distinguish AglB from members of the DPANN super-phylum and the Euryarchaeota from the same enzyme in members of the TACK and Asgard super-phyla, which showed considerable similarity to its eukaryal homologue Stt3. The results thus support the evolutionary proximity of Eukarya and the TACK and Asgard archaea.

RevDate: 2020-09-05

Parks DH, Chuvochina M, Chaumeil PA, et al (2020)

Author Correction: A complete domain-to-species taxonomy for Bacteria and Archaea.

Nature biotechnology, 38(9):1098.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

RevDate: 2020-09-05

Reichart NJ, Jay ZJ, Krukenberg V, et al (2020)

Activity-based cell sorting reveals responses of uncultured archaea and bacteria to substrate amendment.

The ISME journal pii:10.1038/s41396-020-00749-1 [Epub ahead of print].

Metagenomic studies have revolutionized our understanding of the metabolic potential of uncultured microorganisms in various ecosystems. However, many of these genomic predictions have yet to be experimentally tested, and the functional expression of genomic potential often remains unaddressed. In order to obtain a more thorough understanding of cell physiology, novel techniques capable of testing microbial metabolism under close to in situ conditions must be developed. Here, we provide a benchmark study to demonstrate that bioorthogonal non-canonical amino acid tagging (BONCAT) in combination with fluorescence-activated cell sorting (FACS) and 16S rRNA gene sequencing can be used to identify anabolically active members of a microbial community incubated in the presence of various growth substrates or under changing physicochemical conditions. We applied this approach to a hot spring sediment microbiome from Yellowstone National Park (Wyoming, USA) and identified several microbes that changed their activity levels in response to substrate addition, including uncultured members of the phyla Thaumarchaeota, Acidobacteria, and Fervidibacteria. Because shifts in activity in response to substrate amendment or headspace changes are indicative of microbial preferences for particular growth conditions, results from this and future BONCAT-FACS studies could inform the development of cultivation media to specifically enrich uncultured microbes. Most importantly, BONCAT-FACS is capable of providing information on the physiology of uncultured organisms at as close to in situ conditions as experimentally possible.

RevDate: 2020-08-28

Yue L, Li J, Zhang B, et al (2020)

The conserved ribonuclease aCPSF1 triggers genome-wide transcription termination of Archaea via a 3'-end cleavage mode.

Nucleic acids research pii:5898609 [Epub ahead of print].

Transcription termination defines accurate transcript 3'-ends and ensures programmed transcriptomes, making it critical to life. However, transcription termination mechanisms remain largely unknown in Archaea. Here, we reported the physiological significance of the newly identified general transcription termination factor of Archaea, the ribonuclease aCPSF1, and elucidated its 3'-end cleavage triggered termination mechanism. The depletion of Mmp-aCPSF1 in Methanococcus maripaludis caused a genome-wide transcription termination defect and disordered transcriptome. Transcript-3'end-sequencing revealed that transcriptions primarily terminate downstream of a uridine-rich motif where Mmp-aCPSF1 performed an endoribonucleolytic cleavage, and the endoribonuclease activity was determined to be essential to the in vivo transcription termination. Co-immunoprecipitation and chromatin-immunoprecipitation detected interactions of Mmp-aCPSF1 with RNA polymerase and chromosome. Phylogenetic analysis revealed that the aCPSF1 orthologs are ubiquitously distributed among the archaeal phyla, and two aCPSF1 orthologs from Lokiarchaeota and Thaumarchaeota could replace Mmp-aCPSF1 to terminate transcription of M. maripaludis. Therefore, the aCPSF1 dependent termination mechanism could be widely employed in Archaea, including Lokiarchaeota belonging to Asgard Archaea, the postulated archaeal ancestor of Eukaryotes. Strikingly, aCPSF1-dependent archaeal transcription termination reported here exposes a similar 3'-cleavage mode as the eukaryotic RNA polymerase II termination, thus would shed lights on understanding the evolutionary linking between archaeal and eukaryotic termination machineries.

RevDate: 2020-08-27

Tang H, Xiao X, Li C, et al (2020)

Influences of different manure N input on soil ammonia oxidizing archaea and bacteria activity and community structure in a double-cropping rice field.

Journal of applied microbiology [Epub ahead of print].

AIMS: The short-term effects of different organic manure nitrogen (N) input on soil ammonia-oxidizing archaea (AOA) and bacteria (AOB) activity and community structure at maturity stages of early rice and late rice were investigated in the present paper, in a double-cropping rice system of southern China.

METHODS AND RESULTS: A field experiment with five different organic and inorganic N input treatments were applied: (1) 100% N of chemical fertilizer (M0), (2) 30% N of organic manure and 70% N of chemical fertilizer (M30), (3) 50% N of organic manure and 50% N of chemical fertilizer (M50), (4) 100% N of organic manure (M100), and (5) without N fertilizer input as control (CK). Microbial community changes were assessed using fatty acid methyl esters (FAME), and ammonia oxidizer (AO) changes were followed using quantitative PCR. The results showed that AOA were higher than that of AOB based upon amoA gene copy at maturity stages of early rice and late rice. And the abundance of AOB and AOA with M30, M50 and M100 treatments were significantly higher than that of CK treatment. Manure N input treatments had significantly effect on AOB and AOA abundance, and a higher correlation between AOB and manure N input was observed. AOB correlated moderately with soil organic carbon (SOC) content, AOA correlated moderately with water-filled pore space.

CONCLUSIONS: This study found that abundance of AOB and AOA were increased under taken organic N conditions, the soil AOB and AOA community and diversity were changed by short-term different organic manure N input treatments.

Soil microbial community and specific N-utilizing microbial groups were affected by organic manure N input practices.

RevDate: 2020-08-27

Cendron F, Niero G, Carlino G, et al (2020)

Characterizing the fecal bacteria and archaea community of heifers and lactating cows through 16S rRNA next-generation sequencing.

Journal of applied genetics pii:10.1007/s13353-020-00575-3 [Epub ahead of print].

The aim of this study was to describe the fecal bacteria and archaea composition of Holstein-Friesian and Simmental heifers and lactating cows, using 16S rRNA gene sequencing. Bacteria and archaea communities were characterized and compared between heifers and cows of the same breed. Two breeds from different farms were considered, just to speculate about the conservation of the microbiome differences between cows and heifers that undergo different management conditions. The two breeds were from two different herds. Firmicutes, Bacteroidetes, Actinobacteria, and Proteobacteria were the most abundant phyla in all experimental groups. Alpha- and beta-diversity metrics showed significant differences between heifers and cows within the same breed, supported by principal coordinate analysis. The analysis of Holstein-Friesian fecal microbiome composition revealed 3 different bacteria families, 2 genera, and 2 species that differed between heifers and cows; on the other hand, Simmental heifers and cows differed only for one bacteria family, one archaeal genus, and one bacteria species. Results of the present study suggest that fecal communities of heifers and cows are different, and that fecal microbiome is maintained across experimental groups.

RevDate: 2020-08-27

Nagler M, Podmirseg SM, Mayr M, et al (2020)

Quantities of Intra- and Extracellular DNA Reveal Information About Activity and Physiological State of Methanogenic Archaea.

Frontiers in microbiology, 11:1894.

Although being a common aim of many microbial ecology studies, measuring individual physiological conditions of a microbial group or species within a complex consortium is still a challenge. Here, we propose a novel approach that is based on the quantification of sequentially extracted extracellular (exDNA) and intracellular DNA (iDNA) and reveals information about cell lysis and activity of methanogenic archaea within a biogas-producing microbial community. We monitored the methane production rates of differently treated batch anaerobic cultures and compared the concentrations of the alpha subunit of the methyl coenzyme M reductase gene of methanogenic archaea in extracellular and intracellular DNA fractions and in the classically extracted total DNA pool. Our results showed that this fine-tuned DNA approach coupled with the interpretation of the ratio between free exDNA and iDNA considerably improved microbial activity tracking compared to the classical extraction/quantification of total DNA. Additionally, it allowed to identify and quantify methanogenic populations that are inactive and those that are strongly influenced by cell lysis. We argue that despite the need of further studies, this method represents a novel approach to gain specific physiological information from a complex environmental sample and holds the potential to be applied to other microbes of interest.

RevDate: 2020-08-23

Silveira R, Silva MRSS, de Roure Bandeira de Mello T, et al (2020)

Bacteria and Archaea Communities in Cerrado Natural Pond Sediments.

Microbial ecology pii:10.1007/s00248-020-01574-x [Epub ahead of print].

Natural ponds in the Brazilian Cerrado harbor high biodiversity but are still poorly studied, especially their microbial assemblage. The characterization of the microbial community in aquatic environments is fundamental for understanding its functioning, particularly under the increasing pressure posed by land conversion and climate change. Here, we aim to characterize the structure (abundance, richness, and diversity) and composition of the Bacteria and Archaea in the sediment of two natural ponds belonging to different basins that primarily differ in size and depth in the Cerrado. Sediment samples were collected in the dry and rainy seasons and the transition periods between both. The structure and composition of Bacteria and Archaea were assessed by 16S rRNA gene pyrosequencing. We identified 45 bacterial and four archaeal groups. Proteobacteria and Acidobacteria dominated the bacterial community, while Euryarchaeota and Thaumarchaeota dominated the archaeal community. Seasonal fluctuations in the relative abundance of microbial taxa were observed, but pond characteristics were more determinant to community composition differences. Microbial communities are highly diverse, and local variability could partially explain the microbial structure's main differences. Functional predictions based in 16S rRNA gene accessed with Tax4Fun indicated an enriched abundance of predicted methane metabolism in the deeper pond, where higher abundance of methanogenic archaea Methanocella, Methanosaeta, and Methanomicrobiaceae was detected. Our dataset encompasses the more comprehensive survey of prokaryotic microbes in Cerrado's aquatic environments. Here, we present basic and essential information about composition and diversity, for initial insights into the ecology of Bacteria and Archaea in these environments.

RevDate: 2020-08-22

Dhamad AE, DJ Lessner (2020)

A CRISPRi-dCas9 system for archaea and its use to examine gene function during nitrogen fixation by Methanosarcina acetivorans.

Applied and environmental microbiology pii:AEM.01402-20 [Epub ahead of print].

CRISPR-based systems are emerging as the premier method to manipulate many cellular processes. In this study, a simple and efficient CRISPR interference (CRISPRi) system for targeted gene repression in archaea was developed. The Methanosarcina acetivorans CRISPR-Cas9 system was repurposed by replacing Cas9 with the catalytically dead Cas9 (dCas9) to generate a CRISPRi-dCas9 system for targeted gene repression. To test the utility of the system, genes involved in nitrogen (N2) fixation were targeted for dCas9-mediated repression. First, the nif operon (nifHI1I2DKEN) that encodes molybdenum nitrogenase was targeted by separate guide RNAs (gRNA), one targeting the promoter and the other nifD Remarkably, growth of M. acetivorans with N2 was abolished by dCas9-mediated repression of the nif operon with each gRNA. The abundance of nif transcripts was >90% reduced in both strains expressing the gRNAs, and NifD was not detected in cell lysate. Next, we targeted NifB, which is required for nitrogenase cofactor biogenesis. Expression of a gRNA targeting the coding sequence of NifB decreased nifB transcript abundance >85% and impaired but did not abolish growth of M. acetivorans with N2 Finally, to ascertain the ability to study gene regulation using CRISPRi-dCas9, nrpR1 encoding a subunit of the repressor of the nif operon was targeted. The nrpR1 repression strain grew normally with N2 but had increased nif operon transcript abundance consistent with a NrpR1 as repressor. These results highlight the utility of the system, whereby a single gRNA when expressed with dCas9 can block transcription of targeted genes and operons in M. acetivoransIMPORTANCE Genetic tools are needed to understand and manipulate the biology of archaea, which serve critical roles in the biosphere. Methanogenic archaea (methanogens) are essential for the biological production of methane, an intermediate in the global carbon cycle, an important greenhouse gas and a biofuel. The CRISPRi-dCas9 system in the model methanogen M. acetivorans is the first Cas9-based CRISPR interference system in archaea. Results demonstrate that the system is remarkably efficient in targeted gene repression and provide new insight into nitrogen fixation by methanogens, the only archaea with nitrogenase. Overall, the CRISPRi-dCas9 system provides a simple, yet powerful, genetic tool to control the expression of target genes and operons in methanogens.

RevDate: 2020-08-21

Flores-Bautista E, Hernandez-Guerrero R, Huerta-Saquero A, et al (2020)

Deciphering the functional diversity of DNA-binding transcription factors in Bacteria and Archaea organisms.

PloS one, 15(8):e0237135 pii:PONE-D-20-13420.

DNA-binding Transcription Factors (TFs) play a central role in regulation of gene expression in prokaryotic organisms, and similarities at the sequence level have been reported. These proteins are predicted with different abundances as a consequence of genome size, where small organisms contain a low proportion of TFs and large genomes contain a high proportion of TFs. In this work, we analyzed a collection of 668 experimentally validated TFs across 30 different species from diverse taxonomical classes, including Escherichia coli K-12, Bacillus subtilis 168, Corynebacterium glutamicum, and Streptomyces coelicolor, among others. This collection of TFs, together with 111 hidden Markov model profiles associated with DNA-binding TFs collected from diverse databases such as PFAM and DBD, was used to identify the repertoire of proteins putatively devoted to gene regulation in 1321 representative genomes of Archaea and Bacteria. The predicted regulatory proteins were posteriorly analyzed in terms of their genomic context, allowing the prediction of functions for TFs and their neighbor genes, such as genes involved in virulence, enzymatic functions, phosphorylation mechanisms, and antibiotic resistance. The functional analysis associated with PFAM groups showed diverse functional categories were significantly enriched in the collection of TFs and the proteins encoded by the neighbor genes, in particular, small-molecule binding and amino acid transmembrane transporter activities associated with the LysR family and proteins devoted to cellular aromatic compound metabolic processes or responses to drugs, stress, or abiotic stimuli in the MarR family. We consider that with the increasing data derived from new technologies, novel TFs can be identified and help improve the predictions for this class of proteins in complete genomes. The complete collection of experimentally characterized and predicted TFs is available at http://web.pcyt.unam.mx/EntrafDB/.

RevDate: 2020-08-20

Fonseca DR, Halim MFA, Holten MP, et al (2020)

Type IV-like pili facilitate transformation in naturally competent archaea.

Journal of bacteriology pii:JB.00355-20 [Epub ahead of print].

Naturally competent organisms are capable of DNA uptake directly from the environment through the process of transformation. Despite the importance of transformation to microbial evolution, DNA uptake remains poorly characterized outside the bacterial domain. Here, we identify the pilus as a necessary component of the transformation machinery in archaea. We describe two naturally competent organisms: Methanococcus maripaludis and Methanoculleus thermophilus In M. maripaludis, replicative vectors were transferred with an average efficiency of 2.4 x 103 transformants μg-1 DNA. In M. thermophilus, integrative vectors were transferred with an average efficiency of 2.7 x 103 transformants μg-1 DNA. Additionally, natural transformation of M. thermophilus could be used to introduce chromosomal mutations. To our knowledge, this is the first demonstration of a method to introduce targeted mutations in a member of the order Methanomicrobiales. For both organisms, mutants lacking structural components of the type IV-like pilus filament were defective for DNA uptake, demonstrating the importance of pili for natural transformation. Interestingly, competence could be induced in a non-competent strain of M. maripaludis by expressing pilin genes from a replicative vector. These results expand the known natural competence pili to include examples from the archaeal domain and highlight the importance of pili for DNA uptake in diverse microbial organisms.Importance Microbial organisms adapt and evolve by acquiring new genetic material through horizontal gene transfer. One way this occurs is natural transformation, the direct uptake and genomic incorporation of environmental DNA by competent organisms. Archaea represent up to a third of the biodiversity on Earth, yet little is known about transformation in these organisms. Here we provide the first characterization of a component of the archaeal DNA uptake machinery. We show that the type IV-like pilus is essential for natural transformation in two archaeal species. This suggests that pili are important for transformation across the tree of life and further expands our understanding of gene flow in archaea.

RevDate: 2020-08-19

Wang K, Yan H, Peng X, et al (2020)

Community assembly of bacteria and archaea in coastal waters governed by contrasting mechanisms: a seasonal perspective.

Molecular ecology [Epub ahead of print].

Marine planktonic bacteria and archaea commonly exhibit pronounced seasonal succession in community composition. But the existence of seasonality in their assembly processes and between-domain differences in underlying mechanism are largely unassessed. Using a high-coverage sampling strategy (including single sample for each station during four cruises in different seasons), 16S rRNA gene sequencing, and null models, we investigated seasonal patterns in the processes governing spatial turnover of bacteria and archaea in surface coastal waters across a sampling grid over ~300 km in the East China Sea. We found that archaea only bloomed in prokaryotic communities during autumn and winter cruises. Seasonality mostly overwhelmed spatial variability in the compositions of both domains. Bacterial and archaeal communities were dominantly governed by deterministic and stochastic assembly processes, respectively, in autumn cruise, likely due to the differences in niche breadths (bacteria < archaea) and relative abundance (bacteria > archaea). Stochasticity dominated assembly mechanisms of both domains but was driven by distinct processes in winter cruise. Determinism-dominated assembly mechanisms of bacteria rebounded in spring and summer cruises, reflecting seasonal variability in bacterial community assembly. This could be attributed to seasonal changes in bacterial niche breadths and habitat heterogeneity across study area. There were seasonal changes in environmental factors mediating the determinism-stochasticity balance of bacterial community assembly, holding a probability of the existence of unmeasured mediators. Our results suggest contrasting assembly mechanisms of bacteria and archaea in terms of determinism-versus-stochasticity pattern and its seasonality, highlighting the importance of seasonal perspective on microbial community assembly in marine ecosystems.

RevDate: 2020-08-13

Darnell CL, Zheng J, Wilson S, et al (2020)

The Ribbon-Helix-Helix Domain Protein CdrS Regulates the Tubulin Homolog ftsZ2 To Control Cell Division in Archaea.

mBio, 11(4): pii:mBio.01007-20.

Precise control of the cell cycle is central to the physiology of all cells. In prior work we demonstrated that archaeal cells maintain a constant size; however, the regulatory mechanisms underlying the cell cycle remain unexplored in this domain of life. Here, we use genetics, functional genomics, and quantitative imaging to identify and characterize the novel CdrSL gene regulatory network in a model species of archaea. We demonstrate the central role of these ribbon-helix-helix family transcription factors in the regulation of cell division through specific transcriptional control of the gene encoding FtsZ2, a putative tubulin homolog. Using time-lapse fluorescence microscopy in live cells cultivated in microfluidics devices, we further demonstrate that FtsZ2 is required for cell division but not elongation. The cdrS-ftsZ2 locus is highly conserved throughout the archaeal domain, and the central function of CdrS in regulating cell division is conserved across hypersaline adapted archaea. We propose that the CdrSL-FtsZ2 transcriptional network coordinates cell division timing with cell growth in archaea.IMPORTANCE Healthy cell growth and division are critical for individual organism survival and species long-term viability. However, it remains unknown how cells of the domain Archaea maintain a healthy cell cycle. Understanding the archaeal cell cycle is of paramount evolutionary importance given that an archaeal cell was the host of the endosymbiotic event that gave rise to eukaryotes. Here, we identify and characterize novel molecular players needed for regulating cell division in archaea. These molecules dictate the timing of cell septation but are dispensable for growth between divisions. Timing is accomplished through transcriptional control of the cell division ring. Our results shed light on mechanisms underlying the archaeal cell cycle, which has thus far remained elusive.

RevDate: 2020-08-13

Penev PI, Fakhretaha-Aval S, Patel VJ, et al (2020)

Supersized ribosomal RNA expansion segments in Asgard archaea.

Genome biology and evolution pii:5891659 [Epub ahead of print].

The ribosome's common core, comprised of ribosomal RNA (rRNA) and universal ribosomal proteins, connects all life back to a common ancestor and serves as a window to relationships among organisms. The rRNA of the common core is most similar to rRNA of extant bacteria. In eukaryotes, the rRNA of the common core is decorated by expansion segments (ESs) that vastly increase its size. Supersized ESs have not been observed previously in Archaea, and the origin of eukaryotic ESs remains enigmatic. We discovered that the large subunit (LSU) rRNA of two Asgard phyla, Lokiarchaeota and Heimdallarchaeota, considered to be the closest modern archaeal cell lineages to Eukarya, bridge the gap in size between prokaryotic and eukaryotic LSU rRNA. The elongated LSU rRNAs in Lokiarchaeota and Heimdallarchaeota stem from the presence of two supersized ESs, ES9 and ES39. We applied chemical footprinting experiments to study the structure of Lokiarchaeota ES39. Furthermore, we used covariation and sequence analysis to study the evolution of Asgard ES39s and ES9s. By defining the common eukaryotic ES39 signature fold, we found that Asgard ES39s have more and longer helices than eukaryotic ES39s. While Asgard ES39s have sequences and structures distinct from eukaryotic ES39s, we found overall conservation of a three-way junction across the Asgard species that matches eukaryotic ES39 topology, a result consistent with the accretion model of ribosomal evolution.

RevDate: 2020-08-12

Aigle A, Gubry-Rangin C, Thion C, et al (2020)

Experimental testing of hypotheses for temperature- and pH-based niche specialisation of ammonia oxidising archaea and bacteria.

Environmental microbiology [Epub ahead of print].

Investigation of niche specialisation in microbial communities is important in assessing consequences of environmental change for ecosystem processes. Ammonia oxidising bacteria (AOB) and archaea (AOA) present a convenient model for studying niche specialisation. They coexist in most soils and effects of soil characteristics on their relative abundances has been studied extensively. This study integrated published information on the influence of temperature and pH on AOB and AOA into several hypotheses, generating predictions that were tested in soil microcosms. The influence of perturbations in temperature were determined in pH 4.5, 6 and 7.5 soils and perturbations in pH were investigated at 15, 25 and 35°C. AO activities were determined by analysing changes in amoA gene and transcript abundances, stable isotope probing and nitrate production. Experimental data supported major predictions of the effects of temperature and pH, but with several significant discrepancies, some of which may have resulted from experimental limitations. The study also provided evidence for unpredicted activity of AOB in pH 4.5 soil. Other discrepancies highlighted important deficiencies in current knowledge, particularly lack of consideration of niche overlap and the need to consider combinations of factors when assessing the influence of environmental change on microbial communities and their activities. This article is protected by copyright. All rights reserved.

RevDate: 2020-08-10

Alori ET, Emmanuel OC, Glick BR, et al (2020)

Plant-archaea relationships: a potential means to improve crop production in arid and semi-arid regions.

World journal of microbiology & biotechnology, 36(9):133 pii:10.1007/s11274-020-02910-6.

Crop production in arid and semi-arid regions of the world is limited by several abiotic factors, including water stress, temperature extremes, low soil fertility, high soil pH, low soil water-holding capacity, and low soil organic matter. Moreover, arid and semi-arid areas experience low levels of rainfall with high spatial and temporal variability. Also, the indiscriminate use of chemicals, a practice that characterizes current agricultural practice, promotes crop and soil pollution potentially resulting in serious human health and environmental hazards. A reliable and sustainable alternative to current farming practice is, therefore, a necessity. One such option includes the use of plant growth-promoting microbes that can help to ameliorate some of the adverse effects of these multiple stresses. In this regard, archaea, functional components of the plant microbiome that are found both in the rhizosphere and the endosphere may contribute to the promotion of plant growth. Archaea can survive in extreme habitats such as areas with high temperatures and hypersaline water. No cases of archaea pathogenicity towards plants have been reported. Archaea appear to have the potential to promote plant growth, improve nutrient supply and protect plants against various abiotic stresses. A better understanding of recent developments in archaea functional diversity, plant colonizing ability, and modes of action could facilitate their eventual usage as reliable components of sustainable agricultural systems. The research discussed herein, therefore, addresses the potential role of archaea to improve sustainable crop production in arid and semi-arid areas.

RevDate: 2020-08-09

Yang S, Lv Y, Liu X, et al (2020)

Genomic and enzymatic evidence of acetogenesis by anaerobic methanotrophic archaea.

Nature communications, 11(1):3941 pii:10.1038/s41467-020-17860-8.

Anaerobic oxidation of methane (AOM) mediated by anaerobic methanotrophic archaea (ANME) is the primary process that provides energy to cold seep ecosystems by converting methane into inorganic carbon. Notably, cold seep ecosystems are dominated by highly divergent heterotrophic microorganisms. The role of the AOM process in supporting heterotrophic population remains unknown. We investigate the acetogenic capacity of ANME-2a in a simulated cold seep ecosystem using high-pressure biotechnology, where both AOM activity and acetate production are detected. The production of acetate from methane is confirmed by isotope-labeling experiments. A complete archaeal acetogenesis pathway is identified in the ANME-2a genome, and apparent acetogenic activity of the key enzymes ADP-forming acetate-CoA ligase and acetyl-CoA synthetase is demonstrated. Here, we propose a modified model of carbon cycling in cold seeps: during AOM process, methane can be converted into organic carbon, such as acetate, which further fuels the heterotrophic community in the ecosystem.

RevDate: 2020-08-07

Sutter JM, Johnsen U, Reinhardt A, et al (2020)

Pentose degradation in archaea: Halorhabdus species degrade D-xylose, L-arabinose and D-ribose via bacterial-type pathways.

Extremophiles : life under extreme conditions pii:10.1007/s00792-020-01192-y [Epub ahead of print].

The degradation of the pentoses D-xylose, L-arabinose and D-ribose in the domain of archaea, in Haloferax volcanii and in Haloarcula and Sulfolobus species, has been shown to proceed via oxidative pathways to generate α-ketoglutarate. Here, we report that the haloarchaeal Halorhabdus species utilize the bacterial-type non-oxidative degradation pathways for pentoses generating xylulose-5-phosphate. The genes of these pathways are each clustered and were constitutively expressed. Selected enzymes involved in D-xylose degradation, xylose isomerase and xylulokinase, and those involved in L-arabinose degradation, arabinose isomerase and ribulokinase, were characterized. Further, D-ribose degradation in Halorhabdus species involves ribokinase, ribose-5-phosphate isomerase and D-ribulose-5-phosphate-3-epimerase. Ribokinase of Halorhabdus tiamatea and ribose-5-phosphate isomerase of Halorhabdus utahensis were characterized. This is the first report of pentose degradation via the bacterial-type pathways in archaea, in Halorhabdus species that likely acquired these pathways from bacteria. The utilization of bacterial-type pathways of pentose degradation rather than the archaeal oxidative pathways generating α-ketoglutarate might be explained by an incomplete gluconeogenesis in Halorhabdus species preventing the utilization of α-ketoglutarate in the anabolism.

RevDate: 2020-08-07

Wang F, Baquero DP, Beltran LC, et al (2020)

Structures of filamentous viruses infecting hyperthermophilic archaea explain DNA stabilization in extreme environments.

Proceedings of the National Academy of Sciences of the United States of America pii:2011125117 [Epub ahead of print].

Living organisms expend metabolic energy to repair and maintain their genomes, while viruses protect their genetic material by completely passive means. We have used cryo-electron microscopy (cryo-EM) to solve the atomic structures of two filamentous double-stranded DNA viruses that infect archaeal hosts living in nearly boiling acid: Saccharolobus solfataricus rod-shaped virus 1 (SSRV1), at 2.8-Å resolution, and Sulfolobus islandicus filamentous virus (SIFV), at 4.0-Å resolution. The SIFV nucleocapsid is formed by a heterodimer of two homologous proteins and is membrane enveloped, while SSRV1 has a nucleocapsid formed by a homodimer and is not enveloped. In both, the capsid proteins wrap around the DNA and maintain it in an A-form. We suggest that the A-form is due to both a nonspecific desolvation of the DNA by the protein, and a specific coordination of the DNA phosphate groups by positively charged residues. We extend these observations by comparisons with four other archaeal filamentous viruses whose structures we have previously determined, and show that all 10 capsid proteins (from four heterodimers and two homodimers) have obvious structural homology while sequence similarity can be nonexistent. This arises from most capsid residues not being under any strong selective pressure. The inability to detect homology at the sequence level arises from the sampling of viruses in this part of the biosphere being extremely sparse. Comparative structural and genomic analyses suggest that nonenveloped archaeal viruses have evolved from enveloped viruses by shedding the membrane, indicating that this trait may be relatively easily lost during virus evolution.

RevDate: 2020-08-06

Pedone E, Fiorentino G, Bartolucci S, et al (2020)

Enzymatic Antioxidant Signatures in Hyperthermophilic Archaea.

Antioxidants (Basel, Switzerland), 9(8): pii:antiox9080703.

To fight reactive oxygen species (ROS) produced by both the metabolism and strongly oxidative habitats, hyperthermophilic archaea are equipped with an array of antioxidant enzymes whose role is to protect the biological macromolecules from oxidative damage. The most common ROS, such as superoxide radical (O2-.) and hydrogen peroxide (H2O2), are scavenged by superoxide dismutase, peroxiredoxins, and catalase. These enzymes, together with thioredoxin, protein disulfide oxidoreductase, and thioredoxin reductase, which are involved in redox homeostasis, represent the core of the antioxidant system. In this review, we offer a panorama of progression of knowledge on the antioxidative system in aerobic or microaerobic (hyper)thermophilic archaea and possible industrial applications of these enzymes.

RevDate: 2020-08-04

Akıl C, Tran LT, Orhant-Prioux M, et al (2020)

Insights into the evolution of regulated actin dynamics via characterization of primitive gelsolin/cofilin proteins from Asgard archaea.

Proceedings of the National Academy of Sciences of the United States of America pii:2009167117 [Epub ahead of print].

Asgard archaea genomes contain potential eukaryotic-like genes that provide intriguing insight for the evolution of eukaryotes. The eukaryotic actin polymerization/depolymerization cycle is critical for providing force and structure in many processes, including membrane remodeling. In general, Asgard genomes encode two classes of actin-regulating proteins from sequence analysis, profilins and gelsolins. Asgard profilins were demonstrated to regulate actin filament nucleation. Here, we identify actin filament severing, capping, annealing and bundling, and monomer sequestration activities by gelsolin proteins from Thorarchaeota (Thor), which complete a eukaryotic-like actin depolymerization cycle, and indicate complex actin cytoskeleton regulation in Asgard organisms. Thor gelsolins have homologs in other Asgard archaea and comprise one or two copies of the prototypical gelsolin domain. This appears to be a record of an initial preeukaryotic gene duplication event, since eukaryotic gelsolins are generally comprise three to six domains. X-ray structures of these proteins in complex with mammalian actin revealed similar interactions to the first domain of human gelsolin or cofilin with actin. Asgard two-domain, but not one-domain, gelsolins contain calcium-binding sites, which is manifested in calcium-controlled activities. Expression of two-domain gelsolins in mammalian cells enhanced actin filament disassembly on ionomycin-triggered calcium release. This functional demonstration, at the cellular level, provides evidence for a calcium-controlled Asgard actin cytoskeleton, indicating that the calcium-regulated actin cytoskeleton predates eukaryotes. In eukaryotes, dynamic bundled actin filaments are responsible for shaping filopodia and microvilli. By correlation, we hypothesize that the formation of the protrusions observed from Lokiarchaeota cell bodies may involve the gelsolin-regulated actin structures.

RevDate: 2020-07-27

Zhang L, Jiang D, Wu M, et al (2020)

New Insights Into DNA Repair Revealed by NucS Endonucleases From Hyperthermophilic Archaea.

Frontiers in microbiology, 11:1263.

Hyperthermophilic Archaea (HA) thrive in high temperature environments and their genome is facing severe stability challenge due to the increased DNA damage levels caused by high temperature. Surprisingly, HA display spontaneous mutation frequencies similar to mesophilic microorganisms, thereby indicating that the former must possess more efficient DNA repair systems than the latter to counteract the potentially enhanced mutation rates under the harsher environment. Although a few repair proteins or enzymes from HA have been biochemically and structurally characterized, the molecular mechanisms of DNA repair of HA remain largely unknown. Genomic analyses of HA revealed that they lack MutS/MutL homologues of the mismatch repair (MMR) pathway and the recognition proteins of the nucleotide excision repair (NER) pathway. Endonucleases play an essential role in DNA repair. NucS endonuclease, a novel endonuclease recently identified in some HA and bacteria, has been shown to act on branched, mismatched, and deaminated DNA, suggesting that this endonuclease is a multifunctional enzyme involved in NER, MMR, and deaminated base repair in a non-canonical manner. However, the catalytic mechanism and the physiological function of NucS endonucleases from HA need to be further clarified to determine how they participate in the different DNA repair pathways in cells from HA. In this review, we focus on recent advances in our understanding of the function of NucS endonucleases from HA in NER, MMR, and deaminated DNA repair, and propose directions for future studies of the NucS family of endonucleases.

RevDate: 2020-07-21

Charlesworth J, Kimyon O, Manefield M, et al (2020)

Archaea join the conversation: detection of AHL-like activity across a range of archaeal isolates.

FEMS microbiology letters pii:5874252 [Epub ahead of print].

Quorum sensing is a mechanism of genetic control allowing single cell organisms to coordinate phenotypic response(s) across a local population and is often critical for ecosystem function. Although quorum sensing has been extensively studied in bacteria comparatively less is known about this mechanism in Archaea. Given the growing significance of Archaea in both natural and anthropogenic settings, it is important to delineate how widespread this phenomenon of signaling is in this domain. Employing a plasmid-based AHL biosensor in conjunction with thin layer chromatography (TLC), the present study screened a broad range of euryarchaeota isolates for potential signaling activity. Data indicated the presence of 11 new Archaeal isolates with AHL-like activity against the LuxR-based AHL biosensor, including for the first time putative AHL activity in a thermophile. The presence of multiple signals and distinct changes between growth phases were also shown via TLC. Multiple signal molecules were detected using TLC in Haloferax mucosum, Halorubrum kocurii, Natronococcus occultus and Halobacterium salinarium. The finding of multiple novel signal producers suggests the potential for quorum sensing to play an important role not only in the regulation of complex phenotypes within Archaea but the potential for cross-talk with bacterial systems.

RevDate: 2020-07-17

Hogrel G, Lu Y, Alexandre N, et al (2020)

Role of RadA and DNA Polymerases in Recombination-Associated DNA Synthesis in Hyperthermophilic Archaea.

Biomolecules, 10(7): pii:biom10071045.

Among the three domains of life, the process of homologous recombination (HR) plays a central role in the repair of double-strand DNA breaks and the restart of stalled replication forks. Curiously, main protein actors involved in the HR process appear to be essential for hyperthermophilic Archaea raising interesting questions about the role of HR in replication and repair strategies of those Archaea living in extreme conditions. One key actor of this process is the recombinase RadA, which allows the homologous strand search and provides a DNA substrate required for following DNA synthesis and restoring genetic information. DNA polymerase operation after the strand exchange step is unclear in Archaea. Working with Pyrococcus abyssi proteins, here we show that both DNA polymerases, family-B polymerase (PolB) and family-D polymerase (PolD), can take charge of processing the RadA-mediated recombination intermediates. Our results also indicate that PolD is far less efficient, as compared with PolB, to extend the invaded DNA at the displacement-loop (D-loop) substrate. These observations coincide with previous genetic analyses obtained on Thermococcus species showing that PolB is mainly involved in DNA repair without being essential probably because PolD could take over combined with additional partners.

RevDate: 2020-07-13

Wu L, Chen X, Wei W, et al (2020)

A Critical Review on Nitrous Oxide Production by Ammonia-Oxidizing Archaea.

Environmental science & technology [Epub ahead of print].

The continuous increase of nitrous oxide (N2O) in the atmosphere has become a global concern due to its property as a potent greenhouse gas. Given the important role of ammonia-oxidizing archaea (AOA) in ammonia oxidation and their involvement in N2O production, a clear understanding of the knowledge on archaeal N2O production is necessary for global N2O mitigation. Compared to bacterial N2O production by ammonia-oxidizing bacteria (AOB), AOA-driven N2O production pathways are less-well elucidated. In this review, we synthesized the currently proposed AOA-driven N2O production pathways in combination with enzymology distinction, analysed the role of AOA species involved in N2O production pathways, discussed the relative contribution of AOA to N2O production in both natural and anthropogenic environments, summarised the factors affecting archaeal N2O yield, and compared the distinctions among approaches used to differentiate ammonia oxidizer-associated N2O production. We then put forward perspectives for archaeal N2O production and future challenges to further improve our understanding of the production pathways, putative enzymes involved and potential approaches for identification in order to potentially achieve effective N2O mitigations.

RevDate: 2020-07-13

Wang L, Pang Q, Peng F, et al (2020)

Response Characteristics of Nitrifying Bacteria and Archaea Community Involved in Nitrogen Removal and Bioelectricity Generation in Integrated Tidal Flow Constructed Wetland-Microbial Fuel Cell.

Frontiers in microbiology, 11:1385.

This study explores nitrogen removal performance, bioelectricity generation, and the response of microbial community in two novel tidal flow constructed wetland-microbial fuel cells (TFCW-MFCs) when treating synthetic wastewater under two different chemical oxygen demand/total nitrogen (COD/TN, or simplified as C/N) ratios (10:1 and 5:1). The results showed that they achieved high and stable COD, NH4+-N, and TN removal efficiencies. Besides, TN removal rate of TFCW-MFC was increased by 5-10% compared with that of traditional CW-MFC. Molecular biological analysis revealed that during the stabilization period, a low C/N ratio remarkably promoted diversities of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in the cathode layer, whereas a high one enhanced the richness of nitrite-oxidizing bacteria (NOB) in each medium; the dominant genera in AOA, AOB, and NOB were Candidatus Nitrosotenuis, Nitrosomonas, and Nitrobacter. Moreover, a high C/N ratio facilitated the growth of Nitrosomonas, while it inhibited the growth of Candidatus Nitrosotenuis. The distribution of microbial community structures in NOB was separated by space rather than time or C/N ratio, except for Nitrobacter. This is caused by the differences of pH, dissolved oxygen (DO), and nitrogen concentration. The response of microbial community characteristics to nitrogen transformations and bioelectricity generation demonstrated that TN concentration is significantly negatively correlated with AOA-shannon, AOA-chao, 16S rRNA V4-V5-shannon, and 16S rRNA V4-V5-chao, particularly due to the crucial functions of Nitrosopumilus, Planctomyces, and Aquicella. Additionally, voltage output was primarily influenced by microorganisms in the genera of Nitrosopumilus, Nitrosospira, Altererythrobacter, Gemmata, and Aquicella. This study not only presents an applicable tool to treat high nitrogen-containing wastewater, but also provides a theoretical basis for the use of TFCW-MFC and the regulation of microbial community in nitrogen removal and electricity production.

RevDate: 2020-07-08

Qin W, Zheng Y, Zhao F, et al (2020)

Alternative strategies of nutrient acquisition and energy conservation map to the biogeography of marine ammonia-oxidizing archaea.

The ISME journal pii:10.1038/s41396-020-0710-7 [Epub ahead of print].

Ammonia-oxidizing archaea (AOA) are among the most abundant and ubiquitous microorganisms in the ocean, exerting primary control on nitrification and nitrogen oxides emission. Although united by a common physiology of chemoautotrophic growth on ammonia, a corresponding high genomic and habitat variability suggests tremendous adaptive capacity. Here, we compared 44 diverse AOA genomes, 37 from species cultivated from samples collected across diverse geographic locations and seven assembled from metagenomic sequences from the mesopelagic to hadopelagic zones of the deep ocean. Comparative analysis identified seven major marine AOA genotypic groups having gene content correlated with their distinctive biogeographies. Phosphorus and ammonia availabilities as well as hydrostatic pressure were identified as selective forces driving marine AOA genotypic and gene content variability in different oceanic regions. Notably, AOA methylphosphonate biosynthetic genes span diverse oceanic provinces, reinforcing their importance for methane production in the ocean. Together, our combined comparative physiological, genomic, and metagenomic analyses provide a comprehensive view of the biogeography of globally abundant AOA and their adaptive radiation into a vast range of marine and terrestrial habitats.

RevDate: 2020-07-07

Shi X, Gao G, Tian J, et al (2020)

Symbiosis of sulfate-reducing bacteria and methanogenic archaea in sewer systems.

Environment international, 143:105923 pii:S0160-4120(20)31878-X [Epub ahead of print].

Sulfide and methane emissions always simultaneously exist in natural environment and constitute a major topic of societal concern. However, the metabolic environments between sulfate-reducing bacteria (SRB) and methanogenic archaea (MA) exist a great difference, which seems to be opposite to the coexisting phenomenon. To explore this issue, the comprehensive biofilm structures, substrate consuming and metabolism pathways of SRB and MA were investigated in a case study of urban sewers. The results showed that, due to the stricter environmental requirements of MA than SRB, SRB became the preponderant microorganism which promoted the rapid generation of sulfide in the initial period of biofilm formation. According to a metagenomic analysis, the SRB appeared to be more preferential than MA in sewers, and the preponderant SRB could provide a key medium (Methyl-coenzyme M) for methane metabolism. Therefore, the diversity of MA gradually increased, and the symbiosis system formed preliminarily. In addition, via L-cysteine, methane metabolism also participated in sulfide consumption which was involved in cysteine and methionine metabolism. This phenomenon of sulfide consumption led to the forward reaction of sulfide metabolism, which could promote sulfide generation while stabilizing the pH value (H+ concentration) and S2- concentrations which should have inhibited SRB and MA production. Therefore, the heavily intertwined interactions between sulfide and methane metabolism provided environmental security for SRB and MA, and completely formed the symbiosis between SRB and MA. Based on these findings, an ecological model involving synergistic mechanism between sulfide and methane generation is proposed and this model can also improve understanding on the symbiosis of SRB and MA in the natural environment.

RevDate: 2020-07-07

Lin Z, Huang W, Zhou J, et al (2020)

The variation on nitrogen removal mechanisms and the succession of ammonia oxidizing archaea and ammonia oxidizing bacteria with temperature in biofilm reactors treating saline wastewater.

Bioresource technology, 314:123760 pii:S0960-8524(20)31032-4 [Epub ahead of print].

To reveal nitrogen removal mechanisms under environmental stresses, biofilm reactors were operated at different temperatures (10 °C-35 °C) treating saline wastewater (salinity 3%). The results showed nitrogen removal efficiency was 98.46% at 30 °C and 60.85% at 10 °C, respectively. Both ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) participated in nitrification. 94.9% of the overall ammonia oxidation was attributed to AOA at 10 °C, but only 48.2% of that was undertaken by AOA at 35 °C. AOA had a greater contribution at low temperature, which demonstrated that nitrogen removal pathway varied with temperature. Aerobic denitrification was more stable than anoxic denitrification. High-throughput sequencing showed Crenarchaeota was the dominant AOA (97.02-34.47%), cooperating with various heterotrophic AOB. Real-time PCR indicated that AOA was three orders of magnitude more abundant than AOB. AOA was more resistant to low temperature and high-saline stresses. Ammonia oxidizers had distinct responses to temperature change and showed diverse relationships at different temperatures.

RevDate: 2020-07-07

Eichler J (2020)

N-glycosylation in Archaea - New roles for an ancient post-translational modification.

Molecular microbiology [Epub ahead of print].

Genome analysis points to N-glycosylation as being an almost universal post-translational modification in Archaea. Although such predictions have been confirmed in only a limited number of species, such studies are making it increasingly clear that the N-linked glycans which decorate archaeal glycoproteins present diversity in terms of both glycan composition and architecture far beyond what is seen in the other two domains of life. In addition to continuing to decipher pathways of N-glycosylation, recent efforts have revealed how Archaea exploit this variability in novel roles. In addition to encouraging glycoprotein synthesis, folding and assembly into properly functioning higher-ordered complexes, N-glycosylation also provides Archaea with a strategy to cope with changing environments. Archaea can also exploit the apparent species-specific nature of N-glycosylation for selectivity in mating, and hence to maintain species boundaries, and in other events where cell-selective interactions are required. At the same, addressing components of N-glycosylation pathways across archaeal phylogeny offers support for the concept of an archaeal origin for eukaryotes. In this MicroReview, these and other recent discoveries related to N-glycosylation in Archaea are considered.

RevDate: 2020-07-07

Zou D, Wan R, Han L, et al (2020)

Genomic Characteristics of a Novel Species of Ammonia-oxidizing Archaea from the Jiulong River Estuary.

Applied and environmental microbiology pii:AEM.00736-20 [Epub ahead of print].

Ammonia-oxidizing archaea (AOA) are ubiquitous in diverse ecosystems, and play a pivotal role in global nitrogen and carbon cycling. Although AOA diversity and distribution are widely studied mainly based on the amoA (alpha subunit of ammonia monooxygenase) genotypes, only limited investigations addressed the relationship between AOA genetic adaptation, metabolic features, and ecological niches, especially in estuaries. Here, we have described the AOA communities along the Jiulong River Estuary in Southern China. Nine high-quality AOA metagenome-assembled genomes (MAGs) were obtained by metagenomics. Five of the MAGs are proposed to constitute a new species, Ca Nitrosopumilus aestuariumsis sp. nov., based on the phylogenies of the 16S-23S rRNA genes and concatenated ribosomal proteins, as well as the average amino acid identity. Comparative genomic analysis revealed unique features of the new species, including a high number of genes related to diverse carbohydrate-active enzymes, phosphatases, heavy metal transport systems, flagellation, and chemotaxis. These genes may be crucial for AOA adaptation to the eutrophic and heavy metal-contaminated Jiulong River Estuary. The uncovered detailed genomic characteristics of the new estuarine AOA species highlights AOA contribution to ammonia oxidation in the Jiulong River Estuary.IMPORTANCE In this study, AOA communities along a river of Southern China were characterized and metagenome-assembled genomes (MAGs) of a novel AOA clade were also obtained. Based on the characterization of AOA genomes, this study suggested adaptation of the novel AOAs to estuarine environments, providing new information for ecology of estuarine AOA and nitrogen cycle in contaminated estuarine environments.

RevDate: 2020-07-07

Pappenreiter PA, Zwirtmayr S, Mauerhofer LM, et al (2019)

Development of a simultaneous bioreactor system for characterization of gas production kinetics of methanogenic archaea at high pressure.

Engineering in life sciences, 19(7):537-544.

Cultivation of methanogens under high pressure offers a great opportunity in biotechnological processes, one of which is the improvement of the gas-liquid transfer of substrate gases into the medium broth. This article describes a newly developed simultaneous bioreactor system consisting of four identical cultivation vessels suitable for investigation of microbial activity at pressures up to 50 bar and temperatures up to 145°C. Initial pressure studies at 10 and 50 bar of the autotrophic and hydrogenotrophic methanogens Methanothermobacter marburgensis, Methanobacterium palustre, and Methanobacterium thermaggregans were performed to evaluate the reproducibility of the system as well as to test the productivity of these strains. The strains were compared with respect to gas conversion (%), methane evolution rate (MER) (mmol L-1 h-1), turnover rate (h-1), and maximum conversion rate (kmin) (bar h-1). A pressure drop that can be explained by the reaction stoichiometry showed that all tested strains were active under pressurized conditions. Our study sheds light on the production kinetics of methanogenic strains under high-pressure conditions. In addition, the simultaneous bioreactor system is a suitable first step screening system for analyzing the substrate uptake and/or production kinetics of gas conversion and/or gas production processes for barophilic or barotolerant microbes.

RevDate: 2020-07-01

Zhang Y, Zuo JE, Wang SK, et al (2020)

[Spatial Distribution of Nitrogen Metabolism Functional Genes of Eubacteria and Archaebacteria in Dianchi Lake].

Huan jing ke xue= Huanjing kexue, 41(6):2908-2917.

Nitrogen metabolism plays an important role in the nitrogen cycle and transformation in Dianchi Lake. Not only do eukaryotes participate in nitrogen transformation but prokaryotes, as the main drivers of the nitrogen cycle, also play an extremely important role in the nitrogen cycle. Based on 16S rDNA high-throughput sequencing technology, 13 sites in Caohai and Waihai of Dianchi Lake were monitored, and PICRUSt function analysis method was adopted to analyze the microbial community diversity and key genes of nitrogen metabolism in Dianchi Lake. Bacteria belonging to 35 phyla and 427 genera were found in Dianchi Lake water and mainly included Proteobacteria and Bacteroidetes. Archaea had 14 phyla and 61 genera and mainly belonged to Euryarchaeota. The overall bacterial richness index of Dianchi Lake was higher than that of archaea, and the bacterial diversity index of Caohai was higher than that of Waihai. Functional prediction showed functional richness of bacteria and archaea. There were 35 KO pathways involved in nitrogen metabolism in bacteria, including key genes such as nitrogenous nitrate-reducing gene nirB, nitric oxide reductase gene norB in denitrification, and nitroreductase gene nasK. There were 23 KO pathways involved in nitrogen metabolism in archaea, involving nifH, nifK, and nifD nitrogenase genes in nitrogen fixation. The copy number of nitrogenase genes was significantly higher than that of other nitrogenase genes. The copy number of nitrogen-fixing genes of archaea was higher than that of bacteria, the nitrogen metabolism capacity of archaea in Caohai was higher than that in Waihai, and the potential of nitrogen-fixation of archaea in Dianchi Lake water was higher than that of bacteria. From the perspective of community structure and function prediction of bacteria and archaea, this study discussed the differences of nitrogen cycle in bacteria and archaea in different areas of Dianchi Lake and provided a decision basis for water environment management in Dianchi Lake.

RevDate: 2020-06-30

Song Y, Zhu Z, Zhou W, et al (2020)

High-efficiency transformation of archaea by direct PCR products with its application to directed evolution of a thermostable enzyme.

Microbial biotechnology [Epub ahead of print].

Hyperthermophilic archaea with unique biochemical and physiological characteristics are important organisms for fundamental research of life science and have great potential for biotechnological applications. However, low transformation efficiency of foreign DNA molecules impedes developments in genetic modification tools and industrial applications. In this study, we applied prolonged overlap extension PCR (POE-PCR) to generate multimeric DNA molecules and then transformed them into two hyperthermophilic archaea, Thermococcus kodakarensis KOD1 and Pyrococcus yayanosii A1. This study was the first example to demonstrate the enhanced transformation efficiencies of POE-PCR products by a factor of approximately 100 for T. kodakarensis KOD1 and 8 for P. yayanosii A1, respectively, relative to circular shuttle plasmids. Furthermore, directed evolution of a modestly thermophilic enzyme, Methanothermococcus okinawensis 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), was conducted to obtain more stable ones due to high transformation efficiency of T. kodakarensis (i.e. ~3 × 104 CFU per μg DNA). T. kodakarensis harbouring the most thermostable MoHMGR mutant can grow in the presence of a thermostable antibiotic simvastatin at 85°C and even higher temperatures. This high transformation efficiency technique could not only help develop more hyperthermophilic enzyme mutants via directed evolution but also simplify genetical modification of archaea, which could be novel hosts for industrial biotechnology.

RevDate: 2020-06-25

Leoni C, Volpicella M, Fosso B, et al (2020)

A Differential Metabarcoding Approach to Describe Taxonomy Profiles of Bacteria and Archaea in the Saltern of Margherita di Savoia (Italy).

Microorganisms, 8(6): pii:microorganisms8060936.

Microorganisms inhabiting saline environments are an interesting ecological model for the study of the adaptation of organisms to extreme living conditions and constitute a precious resource of enzymes and bioproducts for biotechnological applications. We analyzed the microbial communities in nine ponds with increasing salt concentrations (salinity range 4.9-36.0%) of the Saltern of Margherita di Savoia (Italy), the largest thalassohaline saltern in Europe. A deep-metabarcoding NGS procedure addressing separately the V5-V6 and V3-V4 hypervariable regions of the 16S rRNA gene of Bacteria and Archaea, respectively, and a CARD-FISH (catalyzed reporter deposition fluorescence in situ hybridization) analysis allowed us to profile the dynamics of microbial populations at the different salt concentrations. Both the domains were detected throughout the saltern, even if the low relative abundance of Archaea in the three ponds with the lowest salinities prevented the construction of the relative amplicon libraries. The highest cell counts were recorded at 14.5% salinity for Bacteria and at 24.1% salinity for Archaea. While Bacteria showed the greatest number of genera in the first ponds (salinity range 4.9-14.5%), archaeal genera were more numerous in the last ponds of the saltern (salinity 24.1-36.0%). Among prokaryotes, Salinibacter was the genus with the maximum abundance (~49% at 34.6% salinity). Other genera detected at high abundance were the archaeal Haloquadratum (~43% at 36.0% salinity) and Natronomonas (~18% at 13.1% salinity) and the bacterial "Candidatus Aquiluna" (~19% at 14.5% salinity). Interestingly, "Candidatus Aquiluna" had not been identified before in thalassohaline waters.

RevDate: 2020-06-22

Coker OO, Kai Wu WK, Wong SH, et al (2020)

Altered Gut Archaea Composition and Interaction with Bacteria are Associated with Colorectal Cancer.

Gastroenterology pii:S0016-5085(20)34843-5 [Epub ahead of print].

BACKGROUND & AIMS: Changes in the intestinal microbiota have been associated with development and progression of colorectal cancer (CRC). Archaea are stable components of the microbiota, but little is known about their composition or contribution to colorectal carcinogenesis. We analyzed archaea in fecal microbiomes of 2 large cohorts of patients with CRC.

METHODS: We performed shotgun metagenomic analyses of fecal samples from 585 subjects (184 patients with CRC, 197 patients with adenomas, and 204 healthy individuals [controls]) from discovery (165 individuals) and validation (420 individuals) cohorts. Assignment of taxonomies was performed by exact k-mer alignment against an integrated microbial reference genome database.

RESULTS: Principal component analysis of archaeomes revealed distinct clusters in fecal samples from patients with CRC, patients with adenomas, and controls (P<.001), indicating an alteration in the composition of enteric archaea during tumorigenesis. Fecal samples from patients with CRC had significant enrichment of halophilic and depletion of methanogenic archaea. The halophilic Natrinema sp. J7-2 increased progressively in samples from controls, to patients with adenomas, to patients with CRC. Abundances of 9 archaea species that were enriched in fecal samples from patients with CRC distinguished them from controls with areas under the receiver operating characteristic curve of 0.82 in the discovery cohort and 0.83 in the validation cohort. An association between archaea and bacteria diversities was observed in fecal samples from controls but not from patients with CRC. Archaea that were enriched in fecal samples from patients with CRC had an extensive mutual association with bacteria that were enriched in the same samples, and exclusivity with bacteria that were lost from these samples.

CONCLUSIONS: Archaeomes of fecal samples from patients with CRC are characterized by enrichment of halophiles and depletion of methanogens. Studies are needed to determine whether associations between specific archaea and bacteria species in samples from patients with CRC contribute to or are a response to colorectal tumorigenesis.

RevDate: 2020-06-17

Zhao J, Meng Y, Drewer J, et al (2020)

Differential Ecosystem Function Stability of Ammonia-Oxidizing Archaea and Bacteria following Short-Term Environmental Perturbation.

mSystems, 5(3): pii:5/3/e00309-20.

Rapidly expanding conversion of tropical forests to oil palm plantations in Southeast Asia leads to soil acidification following intensive nitrogen fertilization. Changes in soil pH are predicted to have an impact on archaeal ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), and complete (comammox) ammonia oxidizers and, consequently, on nitrification. It is therefore critical to determine whether the predicted effects of pH on ammonia oxidizers and nitrification activity apply in tropical soils subjected to various degrees of anthropogenic activity. This was investigated by experimental manipulation of pH in soil microcosms from a land-use gradient (forest, riparian, and oil palm soils). The nitrification rate was greater in forest soils with native neutral pH than in converted acidic oil palm soils. Ammonia oxidizer activity decreased following acidification of the forest soils but increased after liming of the oil palm soils, leading to a trend of a reversed net nitrification rate after pH modification. AOA and AOB nitrification activity was dependent on pH, but AOB were more sensitive to pH modification than AOA, which demonstrates a greater stability of AOA than AOB under conditions of short-term perturbation. In addition, these results predict AOB to be a good bioindicator of nitrification response following pH perturbation during land-use conversion. AOB and/or comammox species were active in all soils along the land-use gradient, even, unexpectedly, under acidic conditions, suggesting their adaptation to native acidic or acidified soils. The present study therefore provided evidence for limited stability of soil ammonia oxidizer activity following intensive anthropogenic activities, which likely aggravates the vulnerability of nitrogen cycle processes to environmental disturbance.IMPORTANCE Physiological and ecological studies have provided evidence for pH-driven niche specialization of ammonia oxidizers in terrestrial ecosystems. However, the functional stability of ammonia oxidizers following pH change has not been investigated, despite its importance in understanding the maintenance of ecosystem processes following environmental perturbation. This is particularly true after anthropogenic perturbation, such as the conversion of tropical forest to oil palm plantations. This study demonstrated a great impact of land-use conversion on nitrification, which is linked to changes in soil pH due to common agricultural practices (intensive fertilization). In addition, the different communities of ammonia oxidizers were differently affected by short-term pH perturbations, with implications for future land-use conversions but also for increased knowledge of associated global nitrous oxide emissions and current climate change concerns.

RevDate: 2020-06-14

Di Giulio M (2020)

The phylogenetic distribution of the glutaminyl-tRNA synthetase and Glu-tRNAGln amidotransferase in the fundamental lineages would imply that the ancestor of archaea, that of eukaryotes and LUCA were progenotes.

Bio Systems pii:S0303-2647(20)30073-3 [Epub ahead of print].

The function of the glutaminyl-tRNA synthetase and Glu-tRNAGln amidotransferase might be related to the origin of the genetic code because, for example, glutaminyl-tRNA synthetase catalyses the fundamental reaction that makes the genetic code. If the evolutionary stage of the origin of these two enzymes could be unambiguously identified, then the genetic code should still have been originating at that particular evolutionary stage because the fundamental reaction that makes the code itself was still evidently evolving. This would result in that particular evolutionary moment being attributed to the evolutionary stage of the progenote because it would have a relationship between the genotype and the phenotype not yet fully realized because the genetic code was precisely still originating. I then analyzed the distribution of the glutaminyl-tRNA synthetase and Glu-tRNAGln aminodotrasferase in the main phyletic lineages. Since in some cases the origin of these two enzymes can be related to the evolutionary stages of ancestors of archaea and eukaryotes, this would indicate these ancestors as progenotes because at that evolutionary moment the genetic code was evidently still evolving, thus realizing the definition of progenote. The conclusion that the ancestor of archaea and that of eukaryotes were progenotes would imply that even the last universal common ancestor (LUCA) was a progenote because it appeared, on the tree of life, temporally before these ancestors.

RevDate: 2020-06-13

Pinevich AV (2020)

On the use of basic terms eukaryotic cell/eukaryotes/nucleated organisms, on evolutionary views challenged by the discovery of eukaryotic signatures in asgard archaea, and on a new taxon name for eukaryotes.

Bio Systems pii:S0303-2647(20)30077-0 [Epub ahead of print].

The endosymbiosis theory most widely accepted variant surmises the engulfment of bacterial cell by archaeal cell. For decades, this scenario was reputed to be an unconfirmed hypothesis, and only recently it has obtained an indirect proof in Asgard archaea environmental DNA encoding eukaryotic signatures - actin cytoskeleton, small GTPases, and ESCRT complex. In view of growing interest to this aspect of the endosymbiosis theory, it seemed timely to revisit basic terms eukaryotic cell/eukaryotes/nucleated organisms. The article highlights inadequate applications of these terms, and seeks for their consistency with regard to phylogeny and taxonomy. Additionally, new name Caryosignifera is proposed for the archaeal phylum represented by: (1) several underexplored representatives of Asgard archaea manifested by above-mentioned DNA; (2) extant descendants of extinct engulfing archaea; (3) eukaryotic host cell lineages in modern nucleated organisms (protists, algae, plants, fungi, and animals).

RevDate: 2020-06-12

Gryta A, M Frąc (2020)

Methodological Aspects of Multiplex Terminal Restriction Fragment Length Polymorphism-Technique to Describe the Genetic Diversity of Soil Bacteria, Archaea and Fungi.

Sensors (Basel, Switzerland), 20(11): pii:s20113292.

The molecular fingerprinting methods used to evaluate soil microbial diversity could also be used as effective biosensors for the purposes of monitoring ecological soil status. The biodiversity of microorganisms is a relevant index of soil activity and there is a necessity to develop tools to generate reliable results for an emerging approach in the field of environmental control using microbial diversity biosensors. This work reports a method under development for determining soil microbial diversity using high efficiency Multiplex PCR-Terminal Restriction Fragment Length Polymorphism (M-T-RFLP) for the simultaneous detection of bacteria, archaea and fungi. Three different primer sets were used in the reaction and the analytical conditions were optimized. Optimal analytical conditions were achieved using 0.5 µM of primer for bacteria and 1 µM for archaea and fungi, 4 ng of soil DNA template, and HaeIII restriction enzyme. Comparative tests using the proposed analytical approach and a single analysis of each microorganism group were carried out to indicate that both genetic profiles were similar. The Jaccard similarity coefficient between single and multiplexing approach ranged from 0.773 to 0.850 for bacteria and fungi, and 0.208 to 0.905 for archaea. In conclusion, the multiplexing and pooling approaches significantly reduced the costs and time required to perform the analyses, while maintaining a proper effectiveness.

RevDate: 2020-06-09

Murray AE, Freudenstein J, Gribaldo S, et al (2020)

Roadmap for naming uncultivated Archaea and Bacteria.

Nature microbiology pii:10.1038/s41564-020-0733-x [Epub ahead of print].

The assembly of single-amplified genomes (SAGs) and metagenome-assembled genomes (MAGs) has led to a surge in genome-based discoveries of members affiliated with Archaea and Bacteria, bringing with it a need to develop guidelines for nomenclature of uncultivated microorganisms. The International Code of Nomenclature of Prokaryotes (ICNP) only recognizes cultures as 'type material', thereby preventing the naming of uncultivated organisms. In this Consensus Statement, we propose two potential paths to solve this nomenclatural conundrum. One option is the adoption of previously proposed modifications to the ICNP to recognize DNA sequences as acceptable type material; the other option creates a nomenclatural code for uncultivated Archaea and Bacteria that could eventually be merged with the ICNP in the future. Regardless of the path taken, we believe that action is needed now within the scientific community to develop consistent rules for nomenclature of uncultivated taxa in order to provide clarity and stability, and to effectively communicate microbial diversity.

RevDate: 2020-06-08

Zhou S, Xiang H, JL Liu (2020)

CTP synthase forms cytoophidia in archaea.

Journal of genetics and genomics = Yi chuan xue bao pii:S1673-8527(20)30066-7 [Epub ahead of print].

CTP synthase (CTPS) is an important metabolic enzyme that catalyzes the rate-limiting reaction of nucleotide CTP de novo synthesis. Since 2010, a series of studies have demonstrated that CTPS can form filamentous structures in bacteria and eukaryotes, which are termed cytoophidia. However, it is unknown whether cytoophidia exist in the third domain of life, archaea. Using Haloarcula hispanica as a model system, here we demonstrate that CTPS forms distinct intracellular compartments in archaea. Under stimulated emission depletion microscopy, we find that the structures of H. hispanica CTPS are elongated, similar to cytoophidia in bacteria and eukaryotes. When Haloarcula cells are cultured in low-salt medium, the occurrence of cytoophidia increases dramatically. In addition, treatment of H. hispanica with a glutamine analog or overexpression of CTPS can promote cytoophidium assembly. Our study reveals that CTPS can form cytoophidia in all three domains of life, suggesting that forming cytoophidia is an ancient property of CTPS.

RevDate: 2020-06-05

Anonymous (2020)

Corrigendum to: D-Galactose catabolism in archaea: Operation of the DeLey-Doudoroff pathway in Haloferax volcanii.

FEMS microbiology letters, 367(11):.

RevDate: 2020-06-05

Tang L (2020)

Taxonomy of Bacteria and Archaea.

Nature methods, 17(6):562.

RevDate: 2020-06-05

Peng X, Mayo-Muñoz D, Bhoobalan-Chitty Y, et al (2020)

Anti-CRISPR Proteins in Archaea.

Trends in microbiology pii:S0966-842X(20)30133-5 [Epub ahead of print].

Anti-CRISPR (Acr) proteins are natural inhibitors of CRISPR-Cas immune systems. To date, Acrs inhibiting types I, II, III, V, and VI CRISPR-Cas systems have been characterized. While most known Acrs are derived from bacterial phages and prophages, very few have been characterized in the domain Archaea, despite the nearly ubiquitous presence of CRISPR-Cas in archaeal cells. Here we summarize the discovery and characterization of the archaeal Acrs with the representatives encoded by a model archaeal virus, Sulfolobus islandicus rod-shaped virus 2 (SIRV2). AcrID1 inhibits subtype I-D CRISPR-Cas immunity through direct interaction with the large subunit Cas10d of the effector complex, and AcrIIIB1 inhibits subtype III-B CRISPR-Cas immunity through a mechanism interfering with middle/late gene targeting. Future development of efficient screening methods will be key to uncovering the diversity of archaeal Acrs.

RevDate: 2020-05-25

Qi L, Li J, Jia J, et al (2020)

Comprehensive analysis of the pre-ribosomal RNA maturation pathway in a methanoarchaeon exposes the conserved circularization and linearization mode in archaea.

RNA biology [Epub ahead of print].

The ribosomal RNA (rRNA) genes are generally organized as an operon and cotranscribed into a polycistronic precursor; therefore, processing and maturation of pre-rRNAs are essential for ribosome biogenesis. However, rRNA maturation pathways of archaea, particularly of methanoarchaea, are scarcely known. Here, we thoroughly elucidated the maturation pathway of the rRNA operon (16S-tRNAAla-23S-tRNACys-5S) in Methanolobus psychrophilus, one representative of methanoarchaea. Enzymatic assay demonstrated that EndA, a tRNA splicing endoribonuclease, cleaved bulge-helix-bulge (BHB) motifs buried in the processing stems of pre-16S and pre-23S rRNAs. Northern blot and quantitative PCR detected splicing-coupled circularization of pre-16S and pre-23S rRNAs, which accounted for 2% and 12% of the corresponding rRNAs, respectively. Importantly, endoribonuclease Nob1 was determined to linearize circular pre-16S rRNA at the mature 3' end so to expose the anti-Shine-Dalgarno sequence, while circular pre-23S rRNA was linearized at the mature 5' end by an unknown endoribonuclease. The resultant 5' and 3' extension in linearized pre-16S and pre-23S rRNAs were finally matured through 5'-3' and 3'-5' exoribonucleolytic trimming, respectively. Additionally, a novel processing pathway of endoribonucleolysis coupled with exoribonucleolysis was identified for the pre-5S rRNA maturation in this methanogen, which could be also conserved in most methanogenic euryarchaea. Based on evaluating the phylogenetic conservation of the key elements that are involved in circularization and linearization of pre-rRNA maturation, we predict that the rRNA maturation mode revealed here could be prevalent among archaea.

RevDate: 2020-05-25

Eckert I, Z Weinberg (2020)

Discovery of 20 novel ribosomal leader candidates in bacteria and archaea.

BMC microbiology, 20(1):130 pii:10.1186/s12866-020-01823-6.

BACKGROUND: RNAs perform many functions in addition to supplying coding templates, such as binding proteins. RNA-protein interactions are important in multiple processes in all domains of life, and the discovery of additional protein-binding RNAs expands the scope for studying such interactions. To find such RNAs, we exploited a form of ribosomal regulation. Ribosome biosynthesis must be tightly regulated to ensure that concentrations of rRNAs and ribosomal proteins (r-proteins) match. One regulatory mechanism is a ribosomal leader (r-leader), which is a domain in the 5' UTR of an mRNA whose genes encode r-proteins. When the concentration of one of these r-proteins is high, the protein binds the r-leader in its own mRNA, reducing gene expression and thus protein concentrations. To date, 35 types of r-leaders have been validated or predicted.

RESULTS: By analyzing additional conserved RNA structures on a multi-genome scale, we identified 20 novel r-leader structures. Surprisingly, these included new r-leaders in the highly studied organisms Escherichia coli and Bacillus subtilis. Our results reveal several cases where multiple unrelated RNA structures likely bind the same r-protein ligand, and uncover previously unknown r-protein ligands. Each r-leader consistently occurs upstream of r-protein genes, suggesting a regulatory function. That the predicted r-leaders function as RNAs is supported by evolutionary correlations in the nucleotide sequences that are characteristic of a conserved RNA secondary structure. The r-leader predictions are also consistent with the locations of experimentally determined transcription start sites.

CONCLUSIONS: This work increases the number of known or predicted r-leader structures by more than 50%, providing additional opportunities to study structural and evolutionary aspects of RNA-protein interactions. These results provide a starting point for detailed experimental studies.

RevDate: 2020-05-22

Shi LD, Lv PL, Wang M, et al (2020)

A mixed consortium of methanotrophic archaea and bacteria boosts methane-dependent selenate reduction.

The Science of the total environment, 732:139310 pii:S0048-9697(20)32827-8 [Epub ahead of print].

Though methane-based selenate reduction has been reported, neither the selenate load nor the removal rate could satisfy practical applications, thus limiting this technique to bio-remediate selenate pollution. In the present study, using a membrane biofilm batch reactor (MBBR), we successfully enriched a consortium performing methane-dependent selenate reduction, with enhanced reduction rates from 16.1 to 28.9 μM-day-1 under a comparable Se concentration to industrial wastewaters (i.e., ~500 μM). During active reduction, 16S rRNA gene copies of Archaea and Bacteria were both increased more than one order of magnitude. Clone library construction and high-throughput sequencing indicated that Methanosarcina and Methylocystis were the only methane-oxidizing microorganisms. The presence of 20 mM bromoethanesulphonate or 0.15 mM acetylene both significantly, but not completely, inhibited methane-dependent selenate reduction, indicating the concurrent contributions of methanotrophic archaea and bacteria. Fluorescence in situ hybridization (FISH) revealed that archaea directly adhered to the surface of the membrane while bacteria were in the outer layer, together forming the mature biofilm. This study highlights the crucial role of both methanotrophic archaea and bacteria in methane-dependent selenate reduction, and lays foundations in applying methane to bio-remediate practical selenate pollution.

RevDate: 2020-05-22

Yang D, Xiao X, He N, et al (2020)

Effects of reducing chemical fertilizer combined with organic amendments on ammonia-oxidizing bacteria and archaea communities in a low-fertility red paddy field.

Environmental science and pollution research international pii:10.1007/s11356-020-09120-5 [Epub ahead of print].

Ammonia oxidation process in soil has a great contribution to the emission of nitrous oxide, which is a hot issue in the study of N cycle of rice field ecosystem. Organic amendments which partially substitute chemical nitrogen fertilizer are widely adopted to optimizing N management and reduce the use of chemical nitrogen fertilizers in the paddy ecosystem, but their long-term effects on ammonia-oxidizing archaea (AOA) and bacteria (AOB) were not well understood. Thus, based on a 6-year field trial that comprised four fertilization strategies (CF, chemical fertilizer; PM, pig manure substituting for 20% chemical N; BF, biogas slurry substituting for 20% chemical N; and GM, milk vetch substituting for 20% chemical N) and no N fertilizer application as CK, the abundance and community structure of ammonia oxidizers were examined by using qPCR and Illumina Miseq sequencing approaches based on the functional marker genes (amoA) in a low-fertility paddy field. The results revealed that 6 years of organic-substitute fertilization significantly increased AOA abundance in comparison with NF and CF. However, only CF and PM had a higher AOB abundance than those in NF and no significant difference between CF and organic-substitute treatments was observed. Both AOA and AOB were significantly correlated with soil potential nitrification rate (PNR). Moreover, organic-substitute treatments showed the evident changes in the AOA community, while little were observed in the AOB community. Soil pH was the main predictor for AOA abundance, while NH4+-N and NO3--N were the main predictors for AOB abundance. This study suggests that both AOA and AOB were jointly contributed to the variation of soil potential nitrification rate, while the AOA community was shown to be more responsive to organic-substitute fertilization strategies than AOB in the tested soils.

RevDate: 2020-05-20

Lu Z, Fu T, Li T, et al (2020)

Coevolution of Eukaryote-like Vps4 and ESCRT-III Subunits in the Asgard Archaea.

mBio, 11(3): pii:mBio.00417-20.

The emergence of the endomembrane system is a key step in the evolution of cellular complexity during eukaryogenesis. The endosomal sorting complex required for transport (ESCRT) machinery is essential and required for the endomembrane system functions in eukaryotic cells. Recently, genes encoding eukaryote-like ESCRT protein components have been identified in the genomes of Asgard archaea, a newly proposed archaeal superphylum that is thought to include the closest extant prokaryotic relatives of eukaryotes. However, structural and functional features of Asgard ESCRT remain uncharacterized. Here, we show that Vps4, Vps2/24/46, and Vps20/32/60, the core functional components of the Asgard ESCRT, coevolved eukaryote-like structural and functional features. Phylogenetic analysis shows that Asgard Vps4, Vps2/24/46, and Vps20/32/60 are closely related to their eukaryotic counterparts. Molecular dynamics simulation and biochemical assays indicate that Asgard Vps4 contains a eukaryote-like microtubule-interacting and transport (MIT) domain that binds the distinct type 1 MIT-interacting motif and type 2 MIT-interacting motif in Vps2/24/46 and Vps20/32/60, respectively. The Asgard Vps4 partly, but much more efficiently than homologs from other archaea, complements the vps4 null mutant of Saccharomyces cerevisiae, further supporting the functional similarity between the membrane remodeling machineries of Asgard archaea and eukaryotes. Thus, this work provides evidence that the ESCRT complexes from Asgard archaea and eukaryotes are evolutionarily related and functionally similar. Thus, despite the apparent absence of endomembranes in Asgard archaea, the eukaryotic ESCRT seems to have been directly inherited from an Asgard ancestor, to become a key component of the emerging endomembrane system.IMPORTANCE The discovery of Asgard archaea has changed the existing ideas on the origins of eukaryotes. Researchers propose that eukaryotic cells evolved from Asgard archaea. This hypothesis partly stems from the presence of multiple eukaryotic signature proteins in Asgard archaea, including homologs of ESCRT proteins that are essential components of the endomembrane system in eukaryotes. However, structural and functional features of Asgard ESCRT remain unknown. Our study provides evidence that Asgard ESCRT is functionally comparable to the eukaryotic counterparts, suggesting that despite the apparent absence of endomembranes in archaea, eukaryotic ESCRT was inherited from an Asgard archaeal ancestor, alongside the emergence of endomembrane system during eukaryogenesis.

RevDate: 2020-05-19

Baker BJ, De Anda V, Seitz KW, et al (2020)

Author Correction: Diversity, ecology and evolution of Archaea.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

RevDate: 2020-05-19

Meador TB, Schoffelen N, Ferdelman TG, et al (2020)

Carbon recycling efficiency and phosphate turnover by marine nitrifying archaea.

Science advances, 6(19):eaba1799 pii:aba1799.

Thaumarchaeotal nitrifiers are among the most abundant organisms in the ocean, but still unknown is the carbon (C) yield from nitrification and the coupling of these fluxes to phosphorus (P) turnover and release of metabolites from the cell. Using a dual radiotracer approach, we found that Nitrosopumilus maritimus fixed roughly 0.3 mol C, assimilated 2 mmol P, and released ca. 10-2 mol C and 10-5 mol P as dissolved organics (DOC and DOP) per mole ammonia respired. Phosphate turnover may influence assimilation fluxes by nitrifiers in the euphotic zone, which parallel those of the dark ocean. Collectively, marine nitrifiers assimilate up to 2 Pg C year-1 and 0.05 Pg P year-1 and thereby recycle roughly 5% of mineralized C and P into marine biomass. Release of roughly 50 Tg DOC and 0.2 Tg DOP by thaumarchaea each year represents a small but fresh input of reduced substrates throughout the ocean.

RevDate: 2020-05-19

Takemata N, SD Bell (2020)

Emerging views of genome organization in Archaea.

Journal of cell science, 133(10): pii:133/10/jcs243782.

Over the past decade, advances in methodologies for the determination of chromosome conformation have provided remarkable insight into the local and higher-order organization of bacterial and eukaryotic chromosomes. Locally folded domains are found in both bacterial and eukaryotic genomes, although they vary in size. Importantly, genomes of metazoans also possess higher-order organization into A- and B-type compartments, regions of transcriptionally active and inactive chromatin, respectively. Until recently, nothing was known about the organization of genomes of organisms in the third domain of life - the archaea. However, despite archaea possessing simple circular genomes that are morphologically reminiscent of those seen in many bacteria, a recent study of archaea of the genus Sulfolobus has revealed that it organizes its genome into large-scale domains. These domains further interact to form defined A- and B-type compartments. The interplay of transcription and localization of a novel structural maintenance of chromosomes (SMC) superfamily protein, termed coalescin, defines compartment identity. In this Review, we discuss the mechanistic and evolutionary implications of these findings.

RevDate: 2020-05-18

Lekontseva N, Mikhailina A, Fando M, et al (2020)

Crystal structures and RNA-binding properties of Lsm proteins from archaea Sulfolobus acidocaldarius and Methanococcus vannielii: Similarity and difference of the U-binding mode.

Biochimie pii:S0300-9084(20)30097-3 [Epub ahead of print].

Sm and Sm-like (Lsm) proteins are considered as an evolutionary conserved family involved in RNA metabolism in organisms from bacteria and archaea to human. Currently, the function of Sm-like archaeal proteins (SmAP) is not well understood. Here, we report the crystal structures of SmAP proteins from Sulfolobus acidocaldarius and Methanococcus vannielii and a comparative analysis of their RNA-binding sites. Our data show that these SmAPs have only a uridine-specific RNA-binding site, unlike their bacterial homolog Hfq, which has three different RNA-binding sites. Moreover, variations in the amino acid composition of the U-binding sites of the two SmAPs lead to a difference in protein affinity for oligo(U) RNA. Surface plasmon resonance data and nucleotide-binding analysis confirm the high affinity of SmAPs for uridine nucleotides and oligo(U) RNA and the reduced affinity for adenines, guanines, cytidines and corresponding oligo-RNAs. In addition, we demonstrate that MvaSmAP1 and SacSmAP2 are capable of melting an RNA hairpin and, apparently, promote its interaction with complementary RNA.

RevDate: 2020-05-08

Gelsinger DR, Dallon E, Reddy R, et al (2020)

Ribosome profiling in archaea reveals leaderless translation, novel translational initiation sites, and ribosome pausing at single codon resolution.

Nucleic acids research pii:5831753 [Epub ahead of print].

High-throughput methods, such as ribosome profiling, have revealed the complexity of translation regulation in Bacteria and Eukarya with large-scale effects on cellular functions. In contrast, the translational landscape in Archaea remains mostly unexplored. Here, we developed ribosome profiling in a model archaeon, Haloferax volcanii, elucidating, for the first time, the translational landscape of a representative of the third domain of life. We determined the ribosome footprint of H. volcanii to be comparable in size to that of the Eukarya. We linked footprint lengths to initiating and elongating states of the ribosome on leadered transcripts, operons, and on leaderless transcripts, the latter representing 70% of H. volcanii transcriptome. We manipulated ribosome activity with translation inhibitors to reveal ribosome pausing at specific codons. Lastly, we found that the drug harringtonine arrested ribosomes at initiation sites in this archaeon. This drug treatment allowed us to confirm known translation initiation sites and also reveal putative novel initiation sites in intergenic regions and within genes. Ribosome profiling revealed an uncharacterized complexity of translation in this archaeon with bacteria-like, eukarya-like, and potentially novel translation mechanisms. These mechanisms are likely to be functionally essential and to contribute to an expanded proteome with regulatory roles in gene expression.

RevDate: 2020-05-08

Rawat M, JA Maupin-Furlow (2020)

Redox and Thiols in Archaea.

Antioxidants (Basel, Switzerland), 9(5): pii:antiox9050381.

Low molecular weight (LMW) thiols have many functions in bacteria and eukarya, ranging from redox homeostasis to acting as cofactors in numerous reactions, including detoxification of xenobiotic compounds. The LMW thiol, glutathione (GSH), is found in eukaryotes and many species of bacteria. Analogues of GSH include the structurally different LMW thiols: bacillithiol, mycothiol, ergothioneine, and coenzyme A. Many advances have been made in understanding the diverse and multiple functions of GSH and GSH analogues in bacteria but much less is known about distribution and functions of GSH and its analogues in archaea, which constitute the third domain of life, occupying many niches, including those in extreme environments. Archaea are able to use many energy sources and have many unique metabolic reactions and as a result are major contributors to geochemical cycles. As LMW thiols are major players in cells, this review explores the distribution of thiols and their biochemistry in archaea.

RevDate: 2020-05-06

Li Y, Fan C, Wang L, et al (2020)

Interaction type of tetrabromobisphenol A and copper manipulates ammonia-oxidizing archaea and bacteria communities in co-contaminated river sediments.

Environmental pollution (Barking, Essex : 1987), 264:114671 pii:S0269-7491(19)37793-0 [Epub ahead of print].

The combined contamination of brominated flame retardants (BFRs) and heavy metals in electronic waste (e-waste) recycling and disposal areas has been a serious concern owing to their environmental persistence and chronic toxicities. Ammonia oxidizers, e.g., ammonia-oxidizing archaea (AOA) and bacteria (AOB) play essential roles in nitrogen cycling and can serve as ideal indicators that reflect the changes in sediment health in response to environmental variables. There is currently very little information available on the combined toxic effects of BFRs and heavy metals on AOA and AOB communities. In this study, two typical e-waste pollutants, tetrabromobisphenol A (TBBPA) and copper (Cu), were selected as target contaminants to investigate the individual and combined effects of both pollutants on AOA and AOB communities in river sediments. Respective treatments of TBBPA (1, 10, and 20 mg/kg wet weight), Cu (100 mg/kg wet weight) and their combined treatments (weight ratios of 1:100, 1:10, and 1:5) were performed in laboratory experiments. High-throughput sequencing was applied to explore the response of ammonia oxidizers to TBBPA and Cu. The interaction types of TBBPA and Cu were calculated by the directional classification system to reveal the individual and combined toxicities of both contaminants to the ammonia oxidizers. On days 15 and 30, the dominant interaction type of TBBPA and Cu was synergistic (62.50%), and the combined contamination exacted selective pressure and inhibition on the AOB and AOA communities. On days 45 and 90, the interaction type shifted to be antagonistic (83.33%), with both the AOB and AOA communities gradually reaching stable population equilibria. The alteration of the interaction type is attributed to the elevated TBBPA/Cu tolerance as the incubation time increased. This study disclosed the interaction types of TBBPA and Cu in contaminated river sediments, and revealed that the combined effect could potentially manipulate AOB and AOA communities.

RevDate: 2020-05-06

Juottonen H, Fontaine L, Wurzbacher C, et al (2020)

Archaea in boreal Swedish lakes are diverse, dominated by Woesearchaeota and follow deterministic community assembly.

Environmental microbiology [Epub ahead of print].

Despite their key role in biogeochemical processes, particularly the methane cycle, archaea are widely underrepresented in molecular surveys because of their lower abundance compared to bacteria and eukaryotes. Here, we use parallel high-resolution small subunit rRNA gene sequencing to explore archaeal diversity in 109 Swedish lakes and correlate archaeal community assembly mechanisms to large-scale latitudinal, climatic (nemoral to arctic), and nutrient (oligotrophic to eutrophic) gradients. Sequencing with universal primers showed the contribution of archaea was on average 0.8% but increased up to 1.5% of the three domains in forest lakes. Archaea-specific sequencing revealed that freshwater archaeal diversity could be partly explained by lake variables associated with nutrient status. Combined with deterministic co-occurrence patterns this finding suggests that ecological drift is overridden by environmental sorting, as well as other deterministic processes such as biogeographic and evolutionary history, leading to lake-specific archaeal biodiversity. Acetoclastic, hydrogenotrophic and methylotrophic methanogens as well as ammonia-oxidizing archaea were frequently detected across the lakes. Archaea-specific sequencing also revealed representatives of Woesearchaeota and other phyla of the DPANN superphylum. This study adds to our understanding of the ecological range of key archaea in freshwaters and links these taxa to hypotheses about processes governing biogeochemical cycles in lakes.

RevDate: 2020-05-06

Xie F, Ma A, Zhou H, et al (2020)

Niche differentiation of denitrifying anaerobic methane oxidizing bacteria and archaea leads to effective methane filtration in a Tibetan alpine wetland.

Environment international, 140:105764 pii:S0160-4120(20)30935-1 [Epub ahead of print].

Denitrifying anaerobic methane oxidation (DAMO) is a vital methane sink in wetlands. However, the interactions and niche partitioning of DAMO bacteria and archaea in freshwater wetland soils, in addition to the interactions among microorganisms that couple methane and nitrogen cycling is still unclear, despite that these factors may govern the fate of methane and nitrogen in wetlands. Here, we evaluated the vertical distribution of DAMO bacteria and archaea in soil layers along with the potential interactions among populations in the methane-coupled nitrogen cycling microbial community of Tibetan freshwater wetlands. A combination of molecular biology, stable isotope tracer technology, and microbial bioinformatics was used to evaluate these interrelated dynamics. The abundances and potential methane oxidation rates indicated that DAMO bacteria and archaea differentially occupy surface and subsurface soil layers, respectively. The inferred interactions between DAMO bacteria and nitrogen cycling microorganisms within their communities are complex, DAMO bacteria apparently achieve an advantage in the highly competitive environment of surface soils layers and occupy a specific niche in those environments. Conversely, the apparent relationships between DAMO archaea and nitrogen cycling microorganisms are relatively simple, wherein high levels of cooperation are inferred between DAMO archaea and nitrate-producing organisms in subsurface soils layers. These results suggest that the vertical distribution patterns of DAMO bacteria and archaea enable them to play significant roles in the methane oxidation activity of different soil layers and collectively form an effective methane filtration consortium.

RevDate: 2020-05-05

Wang Y, Wegener G, Ruff SE, et al (2020)

Methyl/alkyl-coenzyme M reductase-based anaerobic alkane oxidation in archaea.

Methyl-coenzyme M reductase (MCR) has been originally identified to catalyze the final step of the methanogenesis pathway. About 20 years ago anaerobic methane-oxidizing archaea (ANME) were discovered that use MCR enzymes to activate methane. ANME thrive at the thermodynamic limit of life, are slow-growing, and in most cases form syntrophic consortia with sulfate-reducing bacteria. Recently, archaea that have the ability to anaerobically oxidize non-methane multi-carbon alkanes such as ethane and n-butane were described in both, enrichment cultures and environmental samples. These anaerobic multi-carbon alkane-oxidizing archaea (ANKA) use enzymes homologous to MCR named alkyl-coenzyme M reductase (ACR). Here we review the recent progresses on the diversity, distribution and functioning of both ANME and ANKA by presenting a detailed MCR/ACR-based phylogeny, compare their metabolic pathways, and discuss the gaps in our knowledge of physiology of these organisms. To improve our understanding of alkane oxidation in archaea, we identified three directions for future research: i) expanding cultivation attempts to validate omics-based metabolic models of yet-uncultured organisms, ii) performing biochemical and structural analyses of key enzymes to understand thermodynamic and steric constraints, iii) investigating evolution of anaerobic alkane metabolisms and their impact on biogeochemical cycles.

RevDate: 2020-05-05

Baker BJ, De Anda V, Seitz KW, et al (2020)

Diversity, ecology and evolution of Archaea.

Nature microbiology pii:10.1038/s41564-020-0715-z [Epub ahead of print].

Compared to bacteria, our knowledge of archaeal biology is limited. Historically, microbiologists have mostly relied on culturing and single-gene diversity surveys to understand Archaea in nature. However, only six of the 27 currently proposed archaeal phyla have cultured representatives. Advances in genomic sequencing and computational approaches are revolutionizing our understanding of Archaea. The recovery of genomes belonging to uncultured groups from the environment has resulted in the description of several new phyla, many of which are globally distributed and are among the predominant organisms on the planet. In this Review, we discuss how these genomes, together with long-term enrichment studies and elegant in situ measurements, are providing insights into the metabolic capabilities of the Archaea. We also debate how such studies reveal how important Archaea are in mediating an array of ecological processes, including global carbon and nutrient cycles, and how this increase in archaeal diversity has expanded our view of the tree of life and early archaeal evolution, and has provided new insights into the origin of eukaryotes.

RevDate: 2020-04-29

DeWerff SJ, Bautista MA, Pauly M, et al (2020)

Killer Archaea: Virus-Mediated Antagonism to CRISPR-Immune Populations Results in Emergent Virus-Host Mutualism.

mBio, 11(2): pii:mBio.00404-20.

Theory, simulation, and experimental evolution demonstrate that diversified CRISPR-Cas immunity to lytic viruses can lead to stochastic virus extinction due to a limited number of susceptible hosts available to each potential new protospacer escape mutation. Under such conditions, theory predicts that to evade extinction, viruses evolve toward decreased virulence and promote vertical transmission and persistence in infected hosts. To better understand the evolution of host-virus interactions in microbial populations with active CRISPR-Cas immunity, we studied the interaction between CRISPR-immune Sulfolobus islandicus cells and immune-deficient strains that are infected by the chronic virus SSV9. We demonstrate that Sulfolobus islandicus cells infected with SSV9, and with other related SSVs, kill uninfected, immune strains through an antagonistic mechanism that is a protein and is independent of infectious virus. Cells that are infected with SSV9 are protected from killing and persist in the population. We hypothesize that this infection acts as a form of mutualism between the host and the virus by removing competitors in the population and ensuring continued vertical transmission of the virus within populations with diversified CRISPR-Cas immunity.IMPORTANCE Multiple studies, especially those focusing on the role of lytic viruses in key model systems, have shown the importance of viruses in shaping microbial populations. However, it has become increasingly clear that viruses with a long host-virus interaction, such as those with a chronic lifestyle, can be important drivers of evolution and have large impacts on host ecology. In this work, we describe one such interaction with the acidic crenarchaeon Sulfolobus islandicus and its chronic virus Sulfolobus spindle-shaped virus 9. Our work expands the view in which this symbiosis between host and virus evolved, describing a killing phenotype which we hypothesize has evolved in part due to the high prevalence and diversity of CRISPR-Cas immunity seen in natural populations. We explore the implications of this phenotype in population dynamics and host ecology, as well as the implications of mutualism between this virus-host pair.

RevDate: 2020-04-28

Parks DH, Chuvochina M, Chaumeil PA, et al (2020)

A complete domain-to-species taxonomy for Bacteria and Archaea.

Nature biotechnology pii:10.1038/s41587-020-0501-8 [Epub ahead of print].

The Genome Taxonomy Database is a phylogenetically consistent, genome-based taxonomy that provides rank-normalized classifications for ~150,000 bacterial and archaeal genomes from domain to genus. However, almost 40% of the genomes in the Genome Taxonomy Database lack a species name. We address this limitation by using commonly accepted average nucleotide identity criteria to set bounds on species and propose species clusters that encompass all publicly available bacterial and archaeal genomes. Unlike previous average nucleotide identity studies, we chose a single representative genome to serve as the effective nomenclatural 'type' defining each species. Of the 24,706 proposed species clusters, 8,792 are based on published names. We assigned placeholder names to the remaining 15,914 species clusters to provide names to the growing number of genomes from uncultivated species. This resource provides a complete domain-to-species taxonomic framework for bacterial and archaeal genomes, which will facilitate research on uncultivated species and improve communication of scientific results.

RevDate: 2020-04-22

Hahn CJ, Laso-Pérez R, Vulcano F, et al (2020)

"Candidatus Ethanoperedens," a Thermophilic Genus of Archaea Mediating the Anaerobic Oxidation of Ethane.

mBio, 11(2): pii:mBio.00600-20.

Cold seeps and hydrothermal vents deliver large amounts of methane and other gaseous alkanes into marine surface sediments. Consortia of archaea and partner bacteria thrive on the oxidation of these alkanes and its coupling to sulfate reduction. The inherently slow growth of the involved organisms and the lack of pure cultures have impeded the understanding of the molecular mechanisms of archaeal alkane degradation. Here, using hydrothermal sediments of the Guaymas Basin (Gulf of California) and ethane as the substrate, we cultured microbial consortia of a novel anaerobic ethane oxidizer, "Candidatus Ethanoperedens thermophilum" (GoM-Arc1 clade), and its partner bacterium "Candidatus Desulfofervidus auxilii," previously known from methane-oxidizing consortia. The sulfate reduction activity of the culture doubled within one week, indicating a much faster growth than in any other alkane-oxidizing archaea described before. The dominance of a single archaeal phylotype in this culture allowed retrieval of a closed genome of "Ca. Ethanoperedens," a sister genus of the recently reported ethane oxidizer "Candidatus Argoarchaeum." The metagenome-assembled genome of "Ca. Ethanoperedens" encoded a complete methanogenesis pathway including a methyl-coenzyme M reductase (MCR) that is highly divergent from those of methanogens and methanotrophs. Combined substrate and metabolite analysis showed ethane as the sole growth substrate and production of ethyl-coenzyme M as the activation product. Stable isotope probing demonstrated that the enzymatic mechanism of ethane oxidation in "Ca. Ethanoperedens" is fully reversible; thus, its enzymatic machinery has potential for the biotechnological development of microbial ethane production from carbon dioxide.IMPORTANCE In the seabed, gaseous alkanes are oxidized by syntrophic microbial consortia that thereby reduce fluxes of these compounds into the water column. Because of the immense quantities of seabed alkane fluxes, these consortia are key catalysts of the global carbon cycle. Due to their obligate syntrophic lifestyle, the physiology of alkane-degrading archaea remains poorly understood. We have now cultivated a thermophilic, relatively fast-growing ethane oxidizer in partnership with a sulfate-reducing bacterium known to aid in methane oxidation and have retrieved the first complete genome of a short-chain alkane-degrading archaeon. This will greatly enhance the understanding of nonmethane alkane activation by noncanonical methyl-coenzyme M reductase enzymes and provide insights into additional metabolic steps and the mechanisms underlying syntrophic partnerships. Ultimately, this knowledge could lead to the biotechnological development of alkanogenic microorganisms to support the carbon neutrality of industrial processes.

RevDate: 2020-04-21

Berkemer SJ, SE McGlynn (2020)

A new analysis of archaea-bacteria domain separation: variable phylogenetic distance and the tempo of early evolution.

Molecular biology and evolution pii:5818498 [Epub ahead of print].

Comparative genomics and molecular phylogenetics are foundational for understanding biological evolution. Although many studies have been made with the aim of understanding the genomic contents of early life, uncertainty remains. A study by Weiss et al. (2016) identified a number of protein families in the last universal common ancestor of archaea and bacteria (LUCA) which were not found in previous works. Here we report new research that suggests the clustering approaches used in this previous study under-sampled protein families, resulting in incomplete phylogenetic trees which do not reflect protein family evolution. Phylogenetic analysis of protein families which include more sequence homologs rejects a simple LUCA hypothesis based on phylogenetic separation of the bacterial and archaeal domains for a majority of the previously identified LUCA proteins (∼82%). To supplement limitations of phylogenetic inference derived from incompletely populated orthologous groups, and to test the hypothesis of a period of rapid evolution preceding the separation of the domains, we compared phylogenetic distances both within, and between domains, for thousands of orthologous groups. We find a substantial diversity of interdomain vs. intradomain branch lengths, even among protein families which exhibit a single domain separating branch and are thought to be associated with the LUCA. Additionally, phylogenetic trees with long interdomain branches relative to intradomain branches are enriched in information categories of protein families in comparison to those associated with metabolic functions. These results provide a new view of protein family evolution, and temper claims about the phenotype and habitat of the LUCA.

RevDate: 2020-04-17

López-García P, D Moreira (2020)

Cultured Asgard Archaea Shed Light on Eukaryogenesis.

Cell, 181(2):232-235.

The first cultured Asgard archaeon lives in metabolic symbiosis with hydrogen-scavenging microbes. Its full-genome analysis authenticates the existence of Asgard archaea, previously only known from metagenome-assembled genomes, confirms their closer phylogenetic relatedness to eukaryotes and reinforces the idea that the eukaryotic cell evolved from an integrated archaeal-bacterial syntrophic consortium.

RevDate: 2020-04-17

Molnár J, Magyar B, Schneider G, et al (2020)

Identification of a novel archaea virus, detected in hydrocarbon polluted Hungarian and Canadian samples.

PloS one, 15(4):e0231864 pii:PONE-D-19-31815.

Metagenomics is a helpful tool for the analysis of unculturable organisms and viruses. Viruses that target bacteria and archaea play important roles in the microbial diversity of various ecosystems. Here we show that Methanosarcina virus MV (MetMV), the second Methanosarcina sp. virus with a completely determined genome, is characteristic of hydrocarbon pollution in environmental (soil and water) samples. It was highly abundant in Hungarian hydrocarbon polluted samples and its genome was also present in the NCBI SRA database containing reads from hydrocarbon polluted samples collected in Canada, indicating the stability of its niche and the marker feature of this virus. MetMV, as the only currently identified marker virus for pollution in environmental samples, could contribute to the understanding of the complicated network of prokaryotes and their viruses driving the decomposition of environmental pollutants.

RevDate: 2020-04-17

Inoue K, Tsunoda SP, Singh M, et al (2020)

Schizorhodopsins: A family of rhodopsins from Asgard archaea that function as light-driven inward H+ pumps.

Science advances, 6(15):eaaz2441 pii:aaz2441.

Schizorhodopsins (SzRs), a rhodopsin family first identified in Asgard archaea, the archaeal group closest to eukaryotes, are present at a phylogenetically intermediate position between typical microbial rhodopsins and heliorhodopsins. However, the biological function and molecular properties of SzRs have not been reported. Here, SzRs from Asgardarchaeota and from a yet unknown microorganism are expressed in Escherichia coli and mammalian cells, and ion transport assays and patch clamp analyses are used to demonstrate SzR as a novel type of light-driven inward H+ pump. The mutation of a cytoplasmic glutamate inhibited inward H+ transport, suggesting that it functions as a cytoplasmic H+ acceptor. The function, trimeric structure, and H+ transport mechanism of SzR are similar to that of xenorhodopsin (XeR), a light-driven inward H+ pumping microbial rhodopsins, implying that they evolved convergently. The inward H+ pump function of SzR provides new insight into the photobiological life cycle of the Asgardarchaeota.

RevDate: 2020-04-16

Tourte M, Schaeffer P, Grossi V, et al (2020)

Functionalized Membrane Domains: An Ancestral Feature of Archaea?.

Frontiers in microbiology, 11:526.

Bacteria and Eukarya organize their plasma membrane spatially into domains of distinct functions. Due to the uniqueness of their lipids, membrane functionalization in Archaea remains a debated area. A novel membrane ultrastructure predicts that monolayer and bilayer domains would be laterally segregated in the hyperthermophilic archaeon Thermococcus barophilus. With very different physico-chemical parameters of the mono- and bilayer, each domain type would thus allow the docking of different membrane proteins and express different biological functions in the membrane. To estimate the ubiquity of this putative membrane ultrastructure in and out of the order Thermococcales, we re-analyzed the core lipid composition of all the Thermococcales type species and collected all the literature data available for isolated archaea. We show that all species of Thermococcales synthesize a mixture of diether bilayer forming and tetraether monolayer forming lipids, in various ratio from 10 to 80% diether in Pyrococcus horikoshii and Thermococcus gorgonarius, respectively. Since the domain formation prediction rests only on the coexistence of di- and tetraether lipids, we show that all Thermococcales have the ability for domain formation, i.e., differential functionalization of their membrane. Extrapolating this view to the whole Archaea domain, we show that almost all archaea also have the ability to synthesize di- and tetraether lipids, which supports the view that functionalized membrane domains may be shared between all Archaea. Hence domain formation and membrane compartmentalization may have predated the separation of the three domains of life and be essential for the cell cycle.

RevDate: 2020-04-13

Fadhlaoui K, Arnal ME, Martineau M, et al (2020)

Archaea, specific genetic traits, and development of improved bacterial live biotherapeutic products: another face of next-generation probiotics.

Applied microbiology and biotechnology pii:10.1007/s00253-020-10599-8 [Epub ahead of print].

Trimethylamine (TMA) and its oxide TMAO are important biomolecules involved in disease-associated processes in humans (e.g., trimethylaminuria and cardiovascular diseases). TMAO in plasma (pTMAO) stems from intestinal TMA, which is formed from various components of the diet in a complex interplay between diet, gut microbiota, and the human host. Most approaches to prevent the occurrence of such deleterious molecules focus on actions to interfere with gut microbiota metabolism to limit the synthesis of TMA. Some human gut archaea however use TMA as terminal electron acceptor for producing methane, thus indicating that intestinal TMA does not accumulate in some human subjects. Therefore, a rational alternative approach is to eliminate neo-synthesized intestinal TMA. This can be achieved through bioremediation of TMA by these peculiar methanogenic archaea, either by stimulating or providing them, leading to a novel kind of next-generation probiotics referred to as archaebiotics. Finally, specific components which are involved in this archaeal metabolism could also be used as intestinal TMA sequesters, facilitating TMA excretion along with stool. Referring to a standard pharmacological approach, these TMA traps could be synthesized ex vivo and then delivered into the human gut. Another approach is the engineering of known probiotic strain in order to metabolize TMA, i.e., live engineered biotherapeutic products. These alternatives would require, however, to take into account the necessity of synthesizing the 22nd amino acid pyrrolysine, i.e., some specificities of the genetics of TMA-consuming archaea. Here, we present an overview of these different strategies and recent advances in the field that will sustain such biotechnological developments. KEY POINTS: • Some autochthonous human archaea can use TMA for their essential metabolism, a methyl-dependent hydrogenotrophic methanogenesis. • They could therefore be used as next-generation probiotics for preventing some human diseases, especially cardiovascular diseases and trimethylaminuria. • Their genetic capacities can also be used to design live recombinant biotherapeutic products. • Encoding of the 22nd amino acid pyrrolysine is necessary for such alternative developments.

RevDate: 2020-04-08

Compte-Port S, Fillol M, Gich F, et al (2020)

Metabolic versatility of freshwater sedimentary archaea feeding on different organic carbon sources.

PloS one, 15(4):e0231238 pii:PONE-D-19-33592.

Members of the phylum Bathyarchaeota and the class Thermoplasmata are widespread in marine and freshwater sediments where they have been recognized as key players in the carbon cycle. Here, we tested the responsiveness of archaeal communities on settled plant debris and sediment from a karstic lake to different organic carbon amendments (amino acids, plant-derived carbohydrates, and aromatics) using a lab-scale microcosm. Changes in the composition and abundance of sediment and biofilm archaeal communities in both DNA and RNA fractions were assessed by 16S rRNA gene amplicon sequencing and qPCR, respectively, after 7 and 30 days of incubation. Archaeal communities showed compositional changes in terms of alpha and beta diversity in relation to the type of carbon source (amino acids vs. plant-derived compounds), the nucleic acid fraction (DNA vs. RNA), and the incubation time (7 vs. 30 days). Distinct groups within the Bathyarchaeota (Bathy-15 and Bathy-6) and the Thermoplasmata (MBG-D) differently reacted to carbon supplements as deduced from the analysis of RNA libraries. Whereas Bathyarchaeota in biofilms showed a long-term positive response to humic acids, their counterparts in the sediment were mainly stimulated by the addition of tryptophan, suggesting the presence of different subpopulations in both habitats. Overall, our work presents an in vitro assessment of the versatility of archaea inhabiting freshwater sediments towards organic carbon and introduces settled leaf litter as a new habitat for the Bathyarchaeota and the Thermoplasmata.

RevDate: 2020-04-05

Jin D, Zhang F, Shi Y, et al (2020)

Diversity of bacteria and archaea in the groundwater contaminated by chlorinated solvents undergoing natural attenuation.

Environmental research, 185:109457 pii:S0013-9351(20)30350-9 [Epub ahead of print].

Chlorinated solvents (CS)-contaminated groundwater poses serious risks to the environment and public health. Microorganisms play a vital role in efficient remediation of CS. In this study, the microbial community (bacterial and archaeal) composition of three CS-contaminated groundwater wells located at an abandoned chemical factory which covers three orders of magnitude in concentration (0.02-16.15 mg/L) were investigated via 16S rRNA gene high-throughput sequencing. The results indicated that Proteobacteria and Thaumarchaeota were the most abundant bacterial and archaeal groups at the phylum level in groundwater, respectively. The major bacterial genera (Flavobacterium sp., Mycobacterium sp. and unclassified Parcubacteria taxa, etc.) and archaeal genera (Thaumarchaeota Group C3, Miscellaneous Crenarchaeotic Group and Miscellaneous Euryarchaeotic Group, etc.) might be involved in the dechlorination processes. In addition, Pearson's correlation analyses showed that alpha diversity of the bacterial community was not significantly correlated with CS concentration, while alpha diversity of archaeal community greatly decreased with the increased contamination of CS. Moreover, partial Mantel test indicated that oxidation-reduction potential, dissolved oxygen, temperature and methane concentration were major drivers of bacterial and archaeal community composition, whereas CS concentration had no significant impact, indicating that both indigenous bacterial and archaeal community compositions are capable of withstanding elevated CS contamination. This study improves our understanding of how the natural microbial community responds to high CS-contaminated groundwater.

RevDate: 2020-04-01

Abril AG, Rama JLR, Sánchez-Pérez A, et al (2020)

Prokaryotic sigma factors and their transcriptional counterparts in Archaea and Eukarya.

Applied microbiology and biotechnology pii:10.1007/s00253-020-10577-0 [Epub ahead of print].

RNA polymerases (RNAPs) carry out transcription in the three domains of life, Bacteria, Archaea, and Eukarya. Transcription initiation is highly regulated by a variety of transcription factors, whose number and subunit complexity increase during evolution. This process is regulated in Bacteria by the σ factor, while the three eukaryotic RNAPs require a complex set of transcription factors (TFs) and a TATA-binding protein (TBP). The archaeal transcription system appears to be an ancestral version of the eukaryotic RNAPII, requiring transcription factor B (TFB), TBP, and transcription factor E (TFE). The function of the bacterial sigma (σ) factor has been correlated to the roles played by the eukaryotic RNAP II and the archaeal RNAP. In addition, σ factors, TFB, and TFIIB all contain multiple DNA binding helix-turn-helix (HTH) structural motifs; although TFIIB and TFB display two HTH domains, while the bacterial σ factor spans 4 HTH motifs. The sequence similarities and structure alignments of the bacterial σ factor, eukaryotic TFIIB, and archaeal TFB evidence that these three proteins are homologs.Key Points• Transcription initiation is highly regulated by TFs.• Transcription is finely regulated in all domains of life by different sets of TFs.• Specific TFs in Bacteria, Eukarya and Archaea are homologs.

RevDate: 2020-03-27

Sun J, Xu Z, B Hao (2010)

Whole-genome based Archaea phylogeny and taxonomy: A composition vector approach.

Chinese science bulletin = Kexue tongbao, 55(22):2323-2328.

The newly proposed alignment-free and parameter-free composition vector (CVtree) method has been successfully applied to infer phylogenetic relationship of viruses, chloroplasts, bacteria, and fungi from their whole-genome data. In this study we pay special attention to the phylogenetic positions of 56 Archaea genomes among which 7 species have not been listed either in Bergey's Manual of Systematic Bacteriology or in Taxonomic Outline of Bacteria and Archaea (TOBA). By inspecting the stable monophyletic branchings in CVTrees reconstructed from a total of 861 genomes (56 Archaea plus 797 Bacteria, using 8 Eukarya as outgroups) definite taxonomic assignments were proposed for these not-fully-classified species. Further development of Archaea taxonomy may verify the predicted phylogenetic results of the CVTree approach.

RevDate: 2020-03-23

Cai M, Liu Y, Yin X, et al (2020)

Diverse Asgard archaea including the novel phylum Gerdarchaeota participate in organic matter degradation.

Science China. Life sciences pii:10.1007/s11427-020-1679-1 [Epub ahead of print].

Asgard is an archaeal superphylum that might hold the key to understand the origin of eukaryotes, but its diversity and ecological roles remain poorly understood. Here, we reconstructed 15 metagenomic-assembled genomes from coastal sediments covering most known Asgard archaea and a novel group, which is proposed as a new Asgard phylum named as the "Gerdarchaeota". Genomic analyses predict that Gerdarchaeota are facultative anaerobes in utilizing both organic and inorganic carbon. Unlike their closest relatives Heimdallarchaeota, Gerdarchaeota have genes encoding for cellulase and enzymes involved in the tetrahydromethanopterin-based Wood-Ljungdahl pathway. Transcriptomics showed that most of our identified Asgard archaea are capable of degrading organic matter, including peptides, amino acids and fatty acids, occupying ecological niches in different depths of layers of the sediments. Overall, this study broadens the diversity of the mysterious Asgard archaea and provides evidence for their ecological roles in coastal sediments.

RevDate: 2020-03-11

Zhao R, Dahle H, Ramírez GA, et al (2020)

Indigenous Ammonia-Oxidizing Archaea in Oxic Subseafloor Oceanic Crust.

mSystems, 5(2): pii:5/2/e00758-19.

Oceanic ridge flank systems represent one of the largest and least-explored microbial habitats on Earth. Fundamental ecological questions regarding community activity, recruitment, and succession in this environment remain unanswered. Here, we investigated ammonia-oxidizing archaea (AOA) in the sediment-buried basalts on the oxic and young ridge flank at North Pond, a sediment-filled pond on the western flank of the Mid-Atlantic Ridge, and compared them with those in the overlying sediments and bottom seawater. Nitrification in the North Pond basement is thermodynamically favorable and is supported by a reaction-transport model simulating the dynamics of nitrate in the crustal fluids. Nitrification rate is estimated to account for 6% to 7% of oxygen consumption, which is similar to the ratios found in marine oxic sediments, suggesting that aerobic mineralization of organic matter is the major ammonium source for crustal nitrifiers. Using the archaeal 16S rRNA and amoA genes as phylogenetic markers, we show that AOA, composed solely of Nitrosopumilaceae, are the major archaeal dwellers at North Pond. Phylogenetic analysis reveals that the crustal AOA communities are distinct from those in the bottom seawater and the upper oxic sediments but are similar to those in the basal part of the overlying sediment column, suggesting either similar environmental selection or the dispersal of microbes across the sediment-basement interface. Additionally, quantitative abundance data suggest enrichment of the dominant Nitrosopumilaceae clade (Eta clade) in the basement compared to the seawater. This study explored AOA and their activity in the upper oceanic crust, and our results have ecological implications for the biogeochemical cycling of nitrogen in the crustal subsurface.IMPORTANCE Ridge flanks represent the major avenue of chemical and heat exchange between the Earth's oceans and the lithosphere and are thought to harbor an enormous and understudied biosphere. However, little is known about the diversity and functionality of the crustal biosphere. Here, we report an indigenous community of archaea specialized in ammonia oxidation (i.e., AOA) in the oxic oceanic crust at North Pond. These AOA are the dominant archaea and are likely responsible for most of the cycling taking place in the first step of nitrification, a feasible nitrogen cycling step in the oxic basement. The crustal AOA community structure significantly differs from that in deep ocean water but is similar to that of the community in the overlying sediments in close proximity. This report links the occurrence of AOA to their metabolic activity in the oxic subseafloor crust and suggests that ecological selection and in situ proliferation may shape the microbial community structure in the rocky subsurface.

RevDate: 2020-03-09

Jeon JH, Lee HS, Shin HC, et al (2020)

Evidence for binary Smc complexes lacking kite subunits in archaea.

IUCrJ, 7(Pt 2):193-206 pii:be5282.

SMC complexes play a central role in chromosome organization in all domains of life. The bacterial Smc-ScpAB complex is a three-subunit complex composed of Smc, ScpA and ScpB. ScpA bridges the two ATPase domains of the Smc homodimer, while ScpB, which belongs to the kite family of proteins, interacts with ScpA. The three subunits are known to be equally important for the function of Smc-ScpAB in bacteria. From crystallographic and biochemical studies, evidence is provided that six archaeal ScpA proteins are unable to interact with the only putative ScpB found in these species. Structure-based sequence alignment reveals that these archaeal ScpAs lack the ScpB-binding segment that is commonly present in the middle of bacterial ScpA sequences, which is thus responsible for their inability to interact with ScpB. ScpA proteins lacking the ScpB-binding segment are found to prevail in archaea. Moreover, two archaeal ScpA proteins with a longer middle region also failed to bind their putative ScpB partner. Furthermore, all or most species belonging to five out of 14 euryarchaeotal orders contain Smc and ScpA but not a detectable ScpB homologue. These data support the notion that archaeal Smc-based complexes generally function as a two-subunit complex composed of only Smc and ScpA.

RevDate: 2020-03-03

Taylor HB, HD Kurtz (Jr) (2020)

Composition, diversity, and activity of aerobic ammonia-oxidizing Bacteria and Archaea in the intertidal sands of a grand strand South Carolina beach.

MicrobiologyOpen [Epub ahead of print].

Aerobic ammonia oxidation to nitrite has been established as an important ecosystem process in regulating the level of nitrogen in marine ecosystems. This process is carried out by ammonia-oxidizing bacteria (AOB) within the classes Betaproteobacteria and Gammaproteobacteria and ammonia-oxidizing Archaea (AOA) from the phylum Thaumarchaeota, and the latter of which has been established as more prevalent in marine systems. This study investigated the presence, abundance, and activity of these groups of microbes at a beach near Springmaid Pier in Myrtle Beach, South Carolina, through the implementation of next generation sequencing, quantitative PCR (qPCR), and microcosm experiments to monitor activity. Sequencing analysis revealed a diverse community of ammonia-oxidizing microbes dominated by AOA classified within the family Nitrosopumilaceae, and qPCR revealed the abundance of AOA amoA genes over AOB by at least an order of magnitude in most samples. Microcosm studies indicate that the rates of potential ammonia oxidation in these communities satisfy Michaelis-Menten substrate kinetics and this process is more active at temperatures corresponding to summer months than winter. Potential rates in AOA medium were higher than that of AOB medium, indicating a potentially greater contribution of AOA to this process in this environment. In conclusion, this study provides further evidence of the dominance of AOA in these environments compared with AOB and highlights the overall efficiency of this process at turning over excess ammonium that may be present in these environments.

RevDate: 2020-02-25

Sanders TJ, Wenck BR, Selan JN, et al (2020)

FttA is a CPSF73 homologue that terminates transcription in Archaea.

Nature microbiology pii:10.1038/s41564-020-0667-3 [Epub ahead of print].

Regulated gene expression is largely achieved by controlling the activities of essential, multisubunit RNA polymerase transcription elongation complexes (TECs). The extreme stability required of TECs to processively transcribe large genomic regions necessitates robust mechanisms to terminate transcription. Efficient transcription termination is particularly critical for gene-dense bacterial and archaeal genomes1-3 in which continued transcription would necessarily transcribe immediately adjacent genes and result in conflicts between the transcription and replication apparatuses4-6; the coupling of transcription and translation7,8 would permit the loading of ribosomes onto aberrant transcripts. Only select sequences or transcription termination factors can disrupt the otherwise extremely stable TEC and we demonstrate that one of the last universally conserved archaeal proteins with unknown biological function is the Factor that terminates transcription in Archaea (FttA). FttA resolves the dichotomy of a prokaryotic gene structure (operons and polarity) and eukaryotic molecular homology (general transcription apparatus) that is observed in Archaea. This missing link between prokaryotic and eukaryotic transcription regulation provides the most parsimonious link to the evolution of the processing activities involved in RNA 3'-end formation in Eukarya.

RevDate: 2020-02-22

Wright CL, Schatteman A, Crombie AT, et al (2020)

Inhibition of ammonia monooxygenase from ammonia oxidising archaea by linear and aromatic alkynes.

Applied and environmental microbiology pii:AEM.02388-19 [Epub ahead of print].

Ammonia monooxygenase (AMO) is a key nitrogen transforming enzyme belonging to the same copper-dependent membrane monooxygenase family (CuMMO) as the particulate methane monooxygenase (pMMO). The AMO from ammonia oxidising archaea (AOA) is very divergent from both the AMO of ammonia oxidising bacteria (AOB) and the pMMO from methanotrophs and little is known about the structure or substrate range of the archaeal AMO. This study compares inhibition by C2-C8 linear 1-alkynes of AMO from two phylogenetically distinct strains of AOA, "Candidatus Nitrosocosmicus franklandus" C13 and "Candidatus Nitrosotalea sinensis" Nd2, with AMO from Nitrosomonas europaea and pMMO from Methylococcus capsulatus (Bath). An increased sensitivity of the archaeal AMO to short-chain-length alkynes (≤C5) appeared to be conserved across AOA lineages. Similarities in C2-C8 alkyne inhibition profiles between AMO from AOA and pMMO from M. capsulatus suggested that the archaeal AMO has a narrower substrate range compared to that of N. europaea AMO. Inhibition of AMO from "Ca. Nitrosocosmicus franklandus" and N. europaea by the aromatic alkyne phenylacetylene was also investigated. Kinetic data revealed that the mechanism by which phenylacetylene inhibits "Ca. Nitrosocosmicus franklandus" and N. europaea is different, indicating differences in the AMO active site between AOA and AOB. Phenylacetylene was found to be a specific and irreversible inhibitor of AMO from "Ca. Nitrosocosmicus franklandus" which does not compete with NH3 for binding at the active site.ImportanceArchaeal and bacterial ammonia oxidisers (AOA and AOB) initiate nitrification by oxidising ammonia to hydroxylamine, a reaction catalysed by ammonia monooxygenase (AMO). AMO enzyme is difficult to purify in active form and its structure and biochemistry remain largely unexplored. The bacterial AMO and the closely related particulate methane monooxygenase (pMMO) have a broad range of hydrocarbon co-oxidation substrates. This study provides insights into the AMO of previously unstudied archaeal genera, by comparing the response of the archaeal AMO, a bacterial AMO and pMMO to inhibition by linear 1-alkynes and the aromatic alkyne, phenylacetylene. Reduced sensitivity to inhibition by larger alkynes suggests that the archaeal AMO has a narrower hydrocarbon substrate range compared to the bacterial AMO, as previously reported for other genera of AOA. Phenylacetylene inhibited the archaeal and bacterial AMO at different thresholds and by different mechanisms of inhibition, highlighting structural differences between the two forms of monooxygenase.

RevDate: 2020-02-22

Yang X, Ni K, Shi Y, et al (2020)

Heavy nitrogen application increases soil nitrification through ammonia-oxidizing bacteria rather than archaea in acidic tea (Camellia sinensis L.) plantation soil.

The Science of the total environment, 717:137248 pii:S0048-9697(20)30758-0 [Epub ahead of print].

Nitrogen (N) fertilizer is widely used in agricultural ecosystems and influences N transformation processes in the soil such as nitrification. However, whether nitrification is primarily dominated by ammonia-oxidizing bacteria (AOB) or archaea (AOA) under heavy N application is still under debate. In the present work, the effect of long-term (12 years) N fertilization on soil nitrification and the key influencing factors were investigated in acidic tea plantation soil that received four different rates of N application (0, 119, 285, and 569 kg N ha-1 yr-1). Nitrification potential was measured and partitioned using chemical inhibitors. The abundance of functional genes involved in ammonia oxidation was quantified using quantitative polymerase chain reaction (qPCR). Ammonia-oxidizing communities were identified by shotgun metagenome sequencing. Potential nitrification rate in tea plantation soil was mainly dominated by autotrophic nitrification (PNRA) (71-79%). PNRA and heterotrophic nitrification (PNRH) were both significantly increased by heavy N (569 kg ha-1) application. Moreover, PNRA was mainly due to the contribution of AOB (52-66%) in N-treated soils, and N569 significantly increased the AOB contribution without affecting the AOA contribution. N569 increased the functional gene abundance of AOB and TAO100 (a non-halophilic γ-AOB) but decreased that of AOA. The dominant AOB (Nitrosomonas, Nitrosospira, and Nitrosococcus), AOA (Nitrososphaera and Nitrosopumilus) and commamox (Nitrospira) groups were profoundly altered by long-term N application rates. Partial least squares regression showed that total nitrification (PNRT), PNRA, and PNRAOB were primarily explained by the functional gene abundance of nitrifiers whereas PNRH and PNRAOA were closely associated with soil and pruned litter properties. Moreover, structural equation modeling (SEM) revealed that long-term N application significantly and indirectly affected nitrification potential by directly influencing soil properties, pruned litter properties, and functional gene abundance. Understanding the relative contribution of AOA and AOB to nitrification may help to better regulate N fertilizer use in agricultural ecosystems.

RevDate: 2020-02-19

Eckl DB, Huber H, W Bäumler (2020)

First Report on Photodynamic Inactivation of Archaea Including a Novel Method for High-Throughput Reduction Measurement.

Photochemistry and photobiology [Epub ahead of print].

Archaea are considered third, independent domain of living organisms besides eukaryotic and bacterial cells. To date, no report is available of photodynamic inactivation (PDI) of any Archaea cells. Two commercially available photosensitizers (SAPYR, TMPyP) were used to investigate photodynamic inactivation of Halobacterium salinarum. In addition, a novel high throughput method was tested to evaluate microbial reduction in vitro. Due to the high salt content of the culture medium, the physical and chemical properties of photosensitizers were analyzed via spectroscopy and fluorescence based DPBF assays. Attachment or uptake of photosensitizers to or in archaeal cells was investigated. The photodynamic inactivation of Halobacterium salinarum was evaluated via growth curve method allowing a high throughput of samples. The presented results indicate that the photodynamic mechanisms are working even in high salt environments. Either photosensitizer inactivated the bacterial cells with a reduction of 99.9% at least. The growth curves provided a fast and precise measurement of cell viability. The results show for the first time that PDI can kill not only bacterial cells but also robust Archaea. The novel method for generating high throughput growth curves provides benefits for future research regarding antimicrobial substances in general.

RevDate: 2020-02-19

Liechty Z, Santos-Medellín C, Edwards J, et al (2020)

Comparative Analysis of Root Microbiomes of Rice Cultivars with High and Low Methane Emissions Reveals Differences in Abundance of Methanogenic Archaea and Putative Upstream Fermenters.

mSystems, 5(1): pii:5/1/e00897-19.

Rice cultivation worldwide accounts for ∼7 to 17% of global methane emissions. Methane cycling in rice paddies is a microbial process not only involving methane producers (methanogens) and methane metabolizers (methanotrophs) but also other microbial taxa that affect upstream processes related to methane metabolism. Rice cultivars vary in their rates of methane emissions, but the influence of rice genotypes on methane cycling microbiota has been poorly characterized. Here, we profiled the rhizosphere, rhizoplane, and endosphere microbiomes of a high-methane-emitting cultivar (Sabine) and a low-methane-emitting cultivar (CLXL745) throughout the growing season to identify variations in the archaeal and bacterial communities relating to methane emissions. The rhizosphere of the high-emitting cultivar was enriched in methanogens compared to that in the low emitter, whereas the relative abundances of methanotrophs between the cultivars were not significantly different. Further analysis of cultivar-sensitive taxa identified families enriched in the high emitter that are associated with methanogenesis-related processes. The high emitter had greater relative abundances of sulfate-reducing and iron-reducing taxa which peak earlier in the season than methanogens and are necessary to lower soil oxidation reduction potential before methanogenesis can occur. The high emitter also had a greater abundance of fermentative taxa which produce methanogenesis precursors (acetate, CO2, and H2). Furthermore, the high emitter was enriched in taxa related to acetogenesis which compete with methanogens for CO2 and H2 These taxa were enriched in a spatio-specific manner and reveal a complex network of microbial interactions on which plant genotype-dependent factors can act to affect methanogenesis and methane emissions.IMPORTANCE Rice cultivation is a major source of anthropogenic emissions of methane, a greenhouse gas with a potentially severe impact on climate change. Emission variation between rice cultivars suggests the feasibility of breeding low-emission rice, but there is a limited understanding of how genotypes affect the microbiota involved in methane cycling. Here, we show that the root microbiome of the high-emitting cultivar is enriched both in methanogens and in taxa associated with fermentation, iron, and sulfate reduction and acetogenesis, processes that support methanogenesis. Understanding how cultivars affect microbes with methanogenesis-related functions is vital for understanding the genetic basis for methane emission in rice and can aid in the development of breeding programs that reduce the environmental impact of rice cultivation.

RevDate: 2020-02-18

Badel C, Da Cunha V, Forterre P, et al (2020)

Pervasive suicidal integrases in deep-sea archaea.

Molecular biology and evolution pii:5739972 [Epub ahead of print].

Mobile genetic elements often encode integrases which catalyze the site-specific insertion of their genetic information into the host genome and the reverse reaction of excision. Hyperthermophilic archaea harbor integrases belonging to the SSV-family which carry the MGE recombination site within their open reading frame. Upon integration into the host genome, SSV integrases disrupt their own gene into two inactive pseudogenes and are termed suicidal for this reason. The evolutionary maintenance of suicidal integrases, concurring with the high prevalence and multiples recruitments of these recombinases by archaeal MGEs, is highly paradoxical. To elucidate this phenomenon, we analyzed the wide phylogenomic distribution of a prominent class of suicidal integrases which revealed a highly variable integration site specificity. Our results highlighted the remarkable hybrid nature of these enzymes encoded from the assembly of inactive pseudogenes of different origins. The characterization of the biological properties of one of these integrases, IntpT26-2 showed that this enzyme was active over a wide range of temperatures up to 99 °C and displayed a less stringent site specificity requirement than comparable integrases. These observations concurred in explaining the pervasiveness of these suicidal integrases in the most hyperthermophilic organisms. The biochemical and phylogenomic data presented here revealed a target site switching system operating on highly thermostable integrases and suggested a new model for split gene reconstitution. By generating fast-evolving pseudogenes at high frequency, suicidal integrases constitute a powerful model to approach the molecular mechanisms involved in the generation of active genes variants by the recombination of proto-genes.

RevDate: 2020-02-14

Tästensen JB, Johnsen U, Reinhardt A, et al (2020)

D-Galactose catabolism in archaea: Operation of the DeLey-Doudoroff pathway in Haloferax volcanii.

FEMS microbiology letters pii:5736015 [Epub ahead of print].

The haloarchaeon Haloferax volcanii was found to grow on D-galactose as carbon and energy source. Here we report a comprehensive analysis of D-galactose catabolism in H. volcanii. Genome analyses indicated a cluster of genes encoding putative enzymes of the DeLey-Doudoroff pathway for D-galactose degradation including galactose dehydrogenase, galactonate dehydratase, 2-keto-3-deoxygalactonate kinase and 2-keto-3-deoxy-6-phosphogalactonate (KDPGal) aldolase. The recombinant galactose dehydrogenase and galactonate dehydratase showed high specificity for D-galactose and galactonate, respectively, whereas KDPGal aldolase was promiscuous in utilizing KDPGal and also the C4 epimer 2-keto-3-deoxy-6-phosphogluconate as substrates. Growth studies with knock-out mutants indicated the functional involvement of galactose dehydrogenase, galactonate dehydratase and KDPGal aldolase in D-galactose degradation. Further, the transcriptional regulator GacR was identified which was characterized as an activator of genes of the DeLey-Doudoroff pathway. Finally, genes were identified encoding components of an ABC transporter and a knock-out mutant of the substrate binding protein indicated the functional involvement of this transporter in D-galactose uptake. This is the first report of D-galactose degradation via the DeLey-Doudoroff pathway in the domain of archaea.

RevDate: 2020-02-12

Roux S, Krupovic M, Daly RA, et al (2020)

Author Correction: Cryptic inoviruses revealed as pervasive in bacteria and archaea across Earth's biomes.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

RevDate: 2020-02-11

Roy D, McEvoy J, E Khan (2020)

Abundance and activity of ammonia oxidizing archaea and bacteria in bulk water and biofilm in water supply systems practicing chlorination and chloramination: Full and laboratory scale investigations.

The Science of the total environment, 715:137043 pii:S0048-9697(20)30553-2 [Epub ahead of print].

The abundance and nitrification activity of ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) in bulk water and biofilm in chloraminated and chlorinated water supply systems were investigated. The abundance of AOB varied between cold and warm periods while that was the case for AOA only in biofilm. Lower ammonia concentrations favored the abundance of AOA over AOB. AOA and AOB were found more in distal zones of the distribution system (DS). Higher numbers of AOA and AOB were observed in DS associated with chloramination compared to those associated with chlorination. Significant positive correlations between ammonia-N in bulk water and AOA indicate a possibility of involvement of AOA in nitrification in DS. A separate laboratory-based experiment simulating DS condition was conducted to understand the effects of chlorine and chloramine dosages and temperature on AOA and AOB. AOA were inhibited less than AOB in the presence of lower concentrations of chlorine and chloramine (1.5 and 2.0 mg/L chlorine; 0.05-0.1 and 0.3-0.4 mg/L chloramine) while both of them were not detected at higher dosages (2.5 mg/L chlorine and 1.5-1.6 mg/L chloramine). At a low temperature (10-12 °C), chloramine and chlorine provided similar inhibition trends in which AOB were inhibited more than AOA. At a high temperature (25 °C), chloramine was less inhibitory to AOA and AOB than chlorine.

RevDate: 2020-02-07

Phung DK, Etienne C, Batista M, et al (2020)

RNA processing machineries in Archaea: the 5'-3' exoribonuclease aRNase J of the β-CASP family is engaged specifically with the helicase ASH-Ski2 and the 3'-5' exoribonucleolytic RNA exosome machinery.

Nucleic acids research pii:5728875 [Epub ahead of print].

A network of RNA helicases, endoribonucleases and exoribonucleases regulates the quantity and quality of cellular RNAs. To date, mechanistic studies focussed on bacterial and eukaryal systems due to the challenge of identifying the main drivers of RNA decay and processing in Archaea. Here, our data support that aRNase J, a 5'-3' exoribonuclease of the β-CASP family conserved in Euryarchaeota, engages specifically with a Ski2-like helicase and the RNA exosome to potentially exert control over RNA surveillance, at the vicinity of the ribosome. Proteomic landscapes and direct protein-protein interaction analyses, strengthened by comprehensive phylogenomic studies demonstrated that aRNase J interplay with ASH-Ski2 and a cap exosome subunit. Finally, Thermococcus barophilus whole-cell extract fractionation experiments provide evidences that an aRNase J/ASH-Ski2 complex might exist in vivo and hint at an association of aRNase J with the ribosome that is emphasised in absence of ASH-Ski2. Whilst aRNase J homologues are found among bacteria, the RNA exosome and the Ski2-like RNA helicase have eukaryotic homologues, underlining the mosaic aspect of archaeal RNA machines. Altogether, these results suggest a fundamental role of β-CASP RNase/helicase complex in archaeal RNA metabolism.

RevDate: 2020-02-06

Lyubetsky VA, Zverkov OA, Rubanov LI, et al (2020)

Optimal Growth Temperature and Intergenic Distances in Bacteria, Archaea, and Plastids of Rhodophytic Branch.

BioMed research international, 2020:3465380.

The lengths of intergenic regions between neighboring genes that are convergent, divergent, or unidirectional were calculated for plastids of the rhodophytic branch and complete archaeal and bacterial genomes. Statistically significant linear relationships between any pair of the medians of these three length types have been revealed in each genomic group. Exponential relationships between the optimal growth temperature and each of the three medians have been revealed as well. The leading coefficients of the regression equations relating all pairs of the medians as well as temperature and any of the medians have the same sign and order of magnitude. The results obtained for plastids, archaea, and bacteria are also similar at the qualitative level. For instance, the medians are always low at high temperatures. At low temperatures, the medians tend to statistically significant greater values and scattering. The original model was used to test our hypothesis that the intergenic distances are optimized in particular to decrease the competition of RNA polymerases within the locus that results in transcribing shortened RNAs. Overall, this points to an effect of temperature for both remote and close genomes.

RevDate: 2020-02-04

Fusco S, Aulitto M, Iacobucci I, et al (2020)

The interaction between the F55 virus-encoded transcription regulator and the RadA host recombinase reveals a common strategy in Archaea and Bacteria to sense the UV-induced damage to the host DNA.

Biochimica et biophysica acta. Gene regulatory mechanisms pii:S1874-9399(19)30442-0 [Epub ahead of print].

Sulfolobus spindle-shaped virus 1 is the only UV-inducible member of the virus family Fuselloviridae. Originally isolated from Saccharolobus shibatae B12, it can also infect Saccharolobus solfataricus. Like the CI repressor of the bacteriophage λ, the SSV1-encoded F55 transcription repressor acts as a key regulator for the maintenance of the SSV1 carrier state. In particular, F55 binds to tandem repeat sequences located within the promoters of the early and UV-inducible transcripts. Upon exposure to UV light, a temporally coordinated pattern of gene expression is triggered. In the case of the better characterized bacteriophage λ, the switch from lysogenic to lytic development is regulated by a crosstalk between the virus encoded CI repressor and the host RecA, which regulates also the SOS response. For SSV1, instead, the regulatory mechanisms governing the switch from the carrier to the induced state have not been completely unravelled. In this study we have applied an integrated biochemical approach based on a variant of the EMSA assay coupled to mass spectrometry analyses to identify the proteins associated with F55 when bound to its specific DNA promoter sequences. Among the putative F55 interactors, we identified RadA and showed that the archaeal molecular components F55 and RadA are functional homologs of bacteriophage λ (factor CI) and Escherichia coli (RecA) system.

RevDate: 2020-02-04

Zhang RY, Zou B, Yan YW, et al (2020)

Design of targeted primers based on 16S rRNA sequences in meta-transcriptomic datasets and identification of a novel taxonomic group in the Asgard archaea.

BMC microbiology, 20(1):25 pii:10.1186/s12866-020-1707-0.

BACKGROUND: Amplification of small subunit (SSU) rRNA genes with universal primers is a common method used to assess microbial populations in various environmental samples. However, owing to limitations in coverage of these universal primers, some microorganisms remain unidentified. The present study aimed to establish a method for amplifying nearly full-length SSU rRNA gene sequences of previously unidentified prokaryotes, using newly designed targeted primers via primer evaluation in meta-transcriptomic datasets.

METHODS: Primer binding regions of universal primer 8F/Arch21F for bacteria or archaea were used for primer evaluation of SSU rRNA sequences in meta-transcriptomic datasets. Furthermore, targeted forward primers were designed based on SSU rRNA reads from unclassified groups unmatched with the universal primer 8F/Arch21F, and these primers were used to amplify nearly full-length special SSU rRNA gene sequences along with universal reverse primer 1492R. Similarity and phylogenetic analysis were used to confirm their novel status.

RESULTS: Using this method, we identified unclassified SSU rRNA sequences that were not matched with universal primer 8F and Arch21F. A new group within the Asgard superphylum was amplified by the newly designed specific primer based on these unclassified SSU rRNA sequences by using mudflat samples.

CONCLUSION: We showed that using specific primers designed based on universal primer evaluation from meta-transcriptomic datasets, identification of novel taxonomic groups from a specific environment is possible.

RevDate: 2020-02-01

Menéndez-Serra M, Ontiveros V, Triadó-Margarit X, et al (2020)

Dynamics and ecological distributions of the Archaea microbiome from inland saline lakes (Monegros Desert, Spain).

FEMS microbiology ecology pii:5719565 [Epub ahead of print].

We characterized the rich Archaea microbiome of shallow inland lakes (Monegros Desert, NE Spain) by 16S rRNA gene tag sequencing covering a wide salinity range (0.1-40% w/v) along three years. Up to 990 OTUs (<97% identity) were detected allocated in 14 major archaeal phyla and heterogeneously distributed along the salt gradient. Dynamics and idiosyncratic ecological distributions were uncovered for the different phyla. A high genetic richness was observed for Woesearchaota and Pacearchaeota (>370 OTUs each), followed by Halobacteria (105), Nanohaloarchaeota (62) and Thermoplasmata (19). Overall, the distribution of genetic richness was strongly correlated with environmental niche amplitude, but not with occurrence. We unveiled high occurrence for a very rich Woesearchaeota assemblage, and an unexpected positive correlation of Pacearchaeota abundance with salinity at >15% dissolved salt content. The estimated dynamic behaviour (temporal 'turnover' rates of presence/absence data) unveiled Thaumarchaeota and Halobacteria as the most dynamic groups, and Aenigmarchaeota and Thermoplasmata as the most stable. The DPANN Pacearchaeota, Woesearchaeota, and Nanohaloarchaeota showed intermediate rates, suggesting higher resilience to environmental perturbations. A rich and dynamic Archaea microbiome was unveiled including unseen ecological traits for relevant members of the still largely unknown DPANN group, supporting a strong ecological differentiation between Pacearchaeota and Woesearchaeota.

RevDate: 2020-01-30

Roy C, Kumar R, S Datta (2020)

Comparative Studies on Ion-pair Energetic, Distribution among Three Domains of Life: Archaea, Eubacteria and Eukarya.

Proteins [Epub ahead of print].

Salt-bridges play a unique role in the structural and functional stability of proteins, especially under harsh environments. How these salt-bridges contribute to the overall thermodynamic stability of protein structure and function across different domains of life is elusive still date. To address the issue, statistical analyses on the energies of salt-bridges, involved in proteins' structure and function, are performed across three domains of life i.e. archaea, eubacteria and eukarya. Results show that although the majority of salt-bridges are stable and conserved, yet the stability of archaeal proteins (∆∆Gnet = -5.06±3.8) is much more than that of eubacteria ∆∆Gnet = -3.7±2.9) and eukarya ∆∆Gnet = -3.54±3.1). Unlike earlier study with archaea, in eukarya and eubacteria, not all buried salt-bridge in our dataset are stable. Buried salt-bridges play surprising role in protein stability, whose variations are clearly observed among these domains. Greater desolvation penalty of buried salt-bridges is compensated by stable network of salt-bridges apart from equal contribution of bridge and background energy terms. On the basis proteins' secondary structure, topology and evolution, our observation show that salt-bridges when present closer to each other in sequence tend to form a greater number. Overall, our comparative study provides insight into the role of specific electrostatic interactions in proteins from different domains of life, which we hope, would be useful for protein engineering and bioinformatics study. This article is protected by copyright. All rights reserved.

RevDate: 2020-01-29

Eichler J (2020)

Modifying Post-Translational Modifications: A Strategy Used by Archaea for Adapting to Changing Environments?: Manipulating the Extent, Position, or Content of Post-Translational Modifications May Help Archaea Adapt to Environmental Change.

BioEssays : news and reviews in molecular, cellular and developmental biology [Epub ahead of print].

In concert with the selective pressures affecting protein folding and function in the extreme environments in which they can exist, proteins in Archaea have evolved to present permanent molecular adaptations at the amino acid sequence level. Such adaptations may not, however, suffice when Archaea encounter transient changes in their surroundings. Post-translational modifications offer a rapid and reversible layer of adaptation for proteins to cope with such situations. Here, it is proposed that Archaea further augment their ability to survive changing growth conditions by modifying the extent, position, and, where relevant, the composition of different post-translational modifications, as a function of the environment. Support for this hypothesis comes from recent reports describing how patterns of protein glycosylation, methylation, and other post-translational modifications of archaeal proteins are altered in response to environmental change. Indeed, adjusting post-translational modifications as a means to cope with environmental variability may also hold true beyond the Archaea.

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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.

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If you thought that the history of life could be organized into a simple tree and that genes only moved from parents to progeny, think again. Recent science has shown that sometimes genes move sideways, skipping the reproductive process, and the tree of life looks more like a tangled bush. David Quammen, a masterful science writer, explains these new findings and more. Read this book and you'll learn about the discovery of the archaea — an entirely different form of life, living right here on this planet, and not noticed until Carl Woese found them, by being among the first to use molecular tools to look at organismal relationships. R. Robbins

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