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Carbon fixation by chemoautotrophic microbes such as homoacetogens had a major impact on the transition from the inorganic to the organic world. Recent reports have shown the presence of genes for key enzymes associated with the Wood–Ljungdahl pathway (WLP) in the phylum Actinobacteria, which adds to the diversity of potential autotrophs. Here, we compiled 42 actinobacterial metagenome-assembled genomes (MAGs) from new and existing metagenomic datasets and propose three novel classes, Ca. Aquicultoria, Ca. Geothermincolia and Ca. Humimicrobiia. Most members of these classes contain genes coding for acetogenesis through the WLP, as well as a variety of hydrogenases (NiFe groups 1a and 3b–3d; FeFe group C; NiFe group 4-related hydrogenases). We show that the three classes acquired the hydrogenases independently, yet the carbon monoxide dehydrogenase/acetyl-CoA synthase complex (CODH/ACS) was apparently present in their last common ancestor and was inherited vertically. Furthermore, the Actinobacteria likely donated genes for CODH/ACS to multiple lineages within Nitrospirae, Deltaproteobacteria (Desulfobacterota), and Thermodesulfobacteria through multiple horizontal gene transfer events. Finally, we show the apparent growth of Ca. Geothermincolia and H(2)-dependent acetate production in hot spring enrichment cultures with or without the methanogenesis inhibitor 2-bromoethanesulfonate, which is consistent with the proposed homoacetogenic metabolism.

The study reports diversity in nitrifying microbial enrichments from low (0·5-5‰) and high (18-35‰) saline ecosystems. Microbial community profiling of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) enrichments was analysed by sequencing 16S rRNA and was processed using Mothur pipeline. The α-diversity indices showed the richness of nitrifying bacterial consortia from the high saline environment and were clustering based on the source of the sample. AOB and NOB enrichments from both the environments showed diverse lineages of phyla distributed in both groups with 38 and 34 phyla from low saline and 53 and 40 phyla in high saline sources, respectively. At class level, α- and γ-proteobacteria were found to be more dominant in both the enrichments. AOBs and NOBs in enrichments from low saline environments were dominated by Nitrosomonadaceae, Gallionellaceae (Nitrotoga sp.) and Ectothiorhodospiraceae and Nitrospira, respectively. Though Chromatiaceae were present in both AOB and NOB enrichments, Nitrosoglobus and Nitrosococcus dominated the AOBs while NOBs were dominated by uncultured genera, whereas Rhizobiales were found in both the enrichments. AOBs and NOBs in enrichments from high saline environments were dominated by Nitrospira-like AOBs, Nitrosomonas and Nitrosococcus genera, whereas ammonia-oxidizing archaea (AOA) group included Nitrosopumilus and Nitrososphaera genera comprising and Nitrospirae, respectively. The majority of the genera obtained in both the salinities were found to be either uncultured or unclassified groups. Results of the study suggest that the AOB and NOB consortia have unique and diverse microbes in each of the enrichments, capable of functioning in aquaculture systems practised at different salinities (0-60 ppt).

Bacteria play a major role in metabolizing ammonia and other metabolites in recirculating aquaculture systems (RASs). To characterize and compare the bacterial communities in the biofilters of two full-scale RASs for the culture of puffer fish, Takifugu rubripes, at different ages and densities were studied. In overall, 47 807 optimized reads of the 16S rRNA gene with V4–V5 region were obtained from four biofilm samples collected after biofilm maturation. At 97% cut-off level, these sequences were clustered into 500 operational taxonomic units, and were classified into 19 bacterial phyla and 138 genera. At the phylum level, Proteobacteria and Bacteroidetes were the most abundant, followed by Nitrospirae and Planctomycetes. At the genus level, Colwellia, Marinifilum, Oceanospirillum, Lutibacter, Winogradskyella, Pseudoalteromonas, Arcobacter, and Phaeobacter were the top members. Nitrosomonas and Nitrospira were main ammonia- and nitrite-oxidizing bacteria. Differences in bacterial communities at different sampling dates and similarities of both biofilters were revealed in the Venn diagram and cluster analysis. Maintaining a good water quality and health of farmed fish in RASs depended on the correct management of the bacterial communities. This study provides more accurate information on the bacterial communities associated with the bifilters of both RASs.

Conventional role of ribosomal proteins is ribosome assembly and protein translation, but some ribosomal proteins also show antimicrobial peptide (AMP) activity, though their mode of action remains ill-defined. Here we demonstrated for the first time that amphioxus RPS15, BjRPS15, was a previously uncharacterized AMP, which was not only capable of identifying Gram-negative and -positive bacteria via interaction with LPS and LTA but also capable of killing the bacteria. We also showed that both the sequence and 3D structure of RPS15 and its prokaryotic homologs were highly conserved, suggesting its antibacterial activity is universal across widely separated taxa. Actually this was supported by the facts that the residues positioned at 45-67 formed the core region for the antimicrobial activity of BjRPS15, and its prokaryotic counterparts, including Nitrospirae RPS1933-55, Aquificae RPS1933-55 and P. syringae RPS1950-72, similarly displayed antibacterial activities. BjRPS15 functioned by both interaction with bacterial surface via LPS and LTA and membrane depolarization as well as induction of intracellular ROS. Moreover, we showed that RPS15 existed extracellularly in amphioxus, shrimp, zebrafish and mice, hinting it may play a critical role in systematic immunity in different animals. In addition, we found that neither BjRPS15 nor its truncated form BjRPS1545-67 were toxic to mammalian cells, making them promising lead molecules for the design of novel AMPs against bacteria. Collectively, these indicate that RPS15 is a new member of AMP with ancient origin and high conservation throughout evolution.

Magnetotactic bacteria (MTB) are prokaryotes that possess genes for the synthesis of membrane-bounded crystals of magnetite or greigite, called magnetosomes. Despite over half a century of studying MTB, only about 60 genomes have been sequenced. Most belong to Proteobacteria, with a minority affiliated with the Nitrospirae, Omnitrophica, Planctomycetes, and Latescibacteria. Due to the scanty information available regarding MTB phylogenetic diversity, little is known about their ecology, evolution and about the magnetosome biomineralization process. This study presents a large-scale search of magnetosome biomineralization genes and reveals 38 new MTB genomes. Several of these genomes were detected in the phyla Elusimicrobia, Candidatus Hydrogenedentes, and Nitrospinae, where magnetotactic representatives have not previously been reported. Analysis of the obtained putative magnetosome biomineralization genes revealed a monophyletic origin capable of putative greigite magnetosome synthesis. The ecological distributions of the reconstructed MTB genomes were also analyzed and several patterns were identified. These data suggest that open databases are an excellent source for obtaining new information of interest.

Diazotrophic microorganisms regulate marine productivity by alleviating nitrogen limitation. However, we know little about the identity and activity of diazotrophs in deep-sea sediments, a habitat covering nearly two-thirds of the planet. Here, we identify candidate diazotrophs from Pacific Ocean sediments collected at 2893 m water depth using 15N-DNA stable isotope probing and a novel pipeline for nifH sequence analysis. Together, these approaches detect an unexpectedly diverse assemblage of active diazotrophs, including members of the Acidobacteria, Firmicutes, Nitrospirae, Gammaproteobacteria, and Deltaproteobacteria. Deltaproteobacteria, predominately members of the Desulfobacterales and Desulfuromonadales, are the most abundant diazotrophs detected, and display the most microdiversity of associated nifH sequences. Some of the detected lineages, including those within the Acidobacteria, have not previously been shown to fix nitrogen. The diazotrophs appear catabolically diverse, with the potential for using oxygen, nitrogen, iron, sulfur, and carbon as terminal electron acceptors. Therefore, benthic diazotrophy may persist throughout a range of geochemical conditions and provide a stable source of fixed nitrogen over geologic timescales. Our results suggest that nitrogen-fixing communities in deep-sea sediments are phylogenetically and catabolically diverse, and open a new line of inquiry into the ecology and biogeochemical impacts of deep-sea microorganisms.

Microbially induced calcium carbonate precipitation (MICP), a widespread biochemical process involving heterotopic bacterial communities, generally occurs in organic matter-rich environments. Limestone caves, whose oligotrophic conditions result from the absence of sunlight, are considered an extreme environment. In such environments, bacteria have the potential to form calcium carbonate. In this study, the microbial community diversity and taxonomical structure outside and inside a limestone cave was investigated with their community-level carbon source by fingerprinting and functional metabolic pathway prediction using 16S rRNA amplicon sequencing analysis. The Biolog EcoPlate™ assay revealed that microbes from outside the cave were metabolically highly active, resulting in a rising carbon source utilization rate curve. Conversely, the microbial community within the cave was not very active in consuming the carbon substrates of Biolog EcoPlate™. Although major carbon sources were found to be used by microbial communities both inside and outside the cave, the microbial utilization rate of carbon bacteria inside was much lower than for bacteria outside the cave. The taxonomic classification of microbial diversity using 16S rRNA metagenomic analysis revealed eight predominant bacterial phyla associated with both sampling areas: Proteobacteria, Acidobacteria, Actinobacteria, Planctomycetes, Nitrospirae, Chloroflexi, Gemmatimonadetes, and Cyanobacteria. Among these, Planctomycetes, Proteobacteria, Cyanobacteria, and Nitrospirae were predominantly associated with external cave samples, whereas Acidobacteria, Actinobacteria, Chloroflexi, and Gemmatimonadetes were associated with internal cave samples. Functional prediction analysis showed that bacterial communities both inside and outside the cave were functionally involved in the metabolism of carbohydrates, amino acids, other amino acid, lipids, xenobiotic compounds, energy metabolism, and environmental information processing. However, the amino acid and carbohydrate metabolic pathways were predominantly linked to the external cave samples, while xenobiotic compounds, lipids, other amino acids, and energy metabolism were associated with internal cave samples. Overall, a positive correlation was observed between Biolog EcoPlate™ assay carbon utilization and metagenomically observed metabolic function.

Using the metagenomics approach and high throughput sequencing of the 16S rRNA gene amplicons, we studied the taxonomic diversity of nitrifying bacteria in microbial communities from epilithic biofilms and plankton of the littoral zone of Lake Baikal. The family Nitrosomonadaceae represents the diversity of ammonia-oxidizing bacteria; the genera (Nitrospirae) and Candidatus Nitrotoga (Gammaproteobacteria) nitrite-oxidizing bacteria; and the phyla Nitrospinae unidentified bacteria. Microbial communities from epilithic biofilms and the near-bottom water layer showed the highest diversity and those from the surface water layer the lowest one. Among ammonia oxidizers, bacteria of the uncultured genus Ellin6067 (27 phylotypes) dominated and were ubiquitous, and among nitrite oxidizers bacteria of the genus Nitrospira (7 phylotypes).

Subsurface ecosystems like groundwater harbour diverse microbial communities, including small-sized, putatively symbiotic organisms of the Candidate Phyla Radiation, yet little is known about their ecological preferences and potential microbial partners. Here, we investigated a member of the superphylum Microgenomates (Cand. Roizmanbacterium ADI133) from oligotrophic groundwater using mini-metagenomics and monitored its spatio-temporal distribution using 16S rRNA gene analyses. A Roizmanbacteria-specific quantitative PCR assay allowed us to track its abundance over the course of 1 year within eight groundwater wells along a 5.4 km hillslope transect, where Roizmanbacteria reached maximum relative abundances of 2.3%. In-depth genomic analyses suggested that Cand. Roizmanbacterium ADI133 is a lactic acid fermenter, potentially able to utilize a range of complex carbon substrates, including cellulose. We hypothesize that it attaches to host cells using a trimeric autotransporter adhesin and inhibits their cell wall biosynthesis using a toxin-antitoxin system. Network analyses based on correlating Cand. Roizmanbacterium ADI133 abundances with amplicon sequencing-derived microbial community profiles suggested one potential host organism, classified as a member of the class Thermodesulfovibrionia (Nitrospirae). By providing lactate as an electron donor Cand. Roizmanbacterium ADI133 potentially mediates the transfer of carbon to other microorganisms and thereby is an important connector in the microbial community.

Long-term intensive greenhouse production commonly leads to continuous cropping obstacles and therefore declines the productivity of greenhouse system, soil microbiological mechanisms behind which remain poorly understood so far. Here, based on a continuous greenhouse cucumber cropping system, the differences in bacterial community structure of the soils with different cucumber cultivation history were assessed through high-throughput sequencing. The β diversity of bacterial community, but not α diversity, significantly changed as consecutive cucumber cultivation and also positively linked to cucumber yield. As for bacterial community members, at phylum level, prolonged cucumber cultivation increased average relative abundances of Chloroflexi and Gemmatimonadetes while decreasing average relative abundance of Nitrospirae; at genus level, continuous cucumber cultivation decreased average relative abundances of some beneficial microbes (i.e. Bacillus, Solirubrobacter, and Rubrobacter) and N-cycling related microbes (i.e. Nitrospira and Azoarcus) while increasing average relative abundance of some functional microbes (i.e. Agromyces, Thermomicrobium, Desulfotomaculum, Sphaerobacter, and Mycobacterium). Soil available phosphorus and organic carbon contents were the most important contributors to the shifts of bacterial community structure. Co-occurrence network analysis indicated long-term greenhouse cucumber cultivation weakened the interaction of species within bacterial community and led to less complex and connected organization among bacterial taxa. Overall, our results suggested that soil bacterial community structure and the interactions of bacterial taxa may play the important roles in the occurrence of continuous cropping obstacles in a long-term intensive greenhouse production system.

Recently, both sand and fly ash have been used for nutrient removal in bioretention systems. However, the improvement in nutrient removal was hampered by a lack of data about of microbial diversity and metabolism effects in the mentioned materials based bioretention systems. Therefore, a mixture with sand, soil and fly ash (1:1:1) was selected as the base in bioretention systems. The investigation of microbial diversity implied that 11 dominant microflora were found, which changed weakly at phylum level but significantly at genus level. The analysis for both urease and extracellular polymer (EPS) showed that urease levels increased with the increase of submerged zone height, which was in line with nitrogen removal, while EPS had the opposite situation. Overall evaluation of microbial role suggested that the enhancement of dominant microflora in the used bioretention systems, like Chloroflexi and Nitrospirae, could strengthen nitrogen removal.

Bacteria are involved in many vital biogeochemical functions in aquatic ecosystems. Owing to their small size and high growth rates, they tend to be highly responsive to any changes in their environment. This potential to reflect any kind of environmental change makes them sensitive indicators towards the effect of pollutants in aquatic systems. The present study focused on investigation of change in the bacterial community structure of Hindon River in Ghaziabad in North India, in relation to the river’s pollution levels. Both spatial and temporal variation in the resident as well as active bacterial community was determined using 16S rRNA gene and transcript as molecular markers through denaturing gradient gel electrophoresis. Sequence analysis of eluted bands showed that Bacteroidetes followed by γ-proteobacteria, Actinobacteria, β-proteobacteria, δ-proteobacteria, e-proteobacteria and Nitrospirae, represented the dominant phyla. Moreover, the effect of pollutants on the bacterial diversity was more conspicuous at RNA level. In addition, when assessing the diversity of culturables, 8 bacterial strains, having minimum inhibitory concentrations in the range of 200–250 mg l−1 for Ni, 75–200 mg l−1 for Co and 75–200 mg l−1 for Cd, were isolated and characterized. The identified bacteria have the potential to be used as sensitive biomarkers for the development of bioremediation strategies and their monitoring.

Unlike other macroecological principles, relationships between productivity and diversity have not been effectively tested for microbial communities. Here we describe an experiment in which the availability of resources to soil bacterial communities was manipulated in a model system, the McMurdo Dry Valleys of Antarctica. Mannitol additions were used to simulate a productivity gradient such that a response in bacterial biomass production, taxonomic diversity and functioning (e.g., enzyme activity) were induced. Resource amendment induced a positive linear response in microbial productivity (P < 0.001) but a unimodal (hump-shaped) response in microbial diversity at multiple taxonomic scales (P = 0.035). Putative oligotrophic (e.g., phyla Nitrospirae and Cyanobacteria) and copiotrophic (e.g., phylum Proteobacteria) taxa were apparent through substantial community turnover along the resource gradient. Soil enzyme activity was inversely related to bacterial biomass but positively related to diversity, suggesting the latter may be a stronger control over enzyme-mediated decomposition. The mechanisms behind this pattern are consistent with macroecological theory of a shift from environmental (e.g., stress tolerance) to biotic (e.g., competition) drivers with increasing resource availability. This evidence is among the first of its kind to document a significant unimodal productivity-diversity relationship for soil bacteria.

Magnetotactic bacteria (MTB) play an important role in biogeochemical cycles of iron and remanent magnetization acquisition of sediments. It is generally considered that magnetite-producing MTB prefer chemical conditions in the oxic-anoxic transition zone (OATZ). We studied the distribution of fossil MTB magnetite (magnetofossils) and microbes phylogenetically related to MTB within deep-sea surface sediments across the OATZ. Transmission electron microscope (TEM) observations and rock-magnetic proxies show that magnetofossils commonly occur both within the OATZ and above it, even at the top of surface oxidized layers, and that the proportion of magnetofossils with a teardrop morphology increases within the OATZ. Consistent results were obtained from the pyrosequencing of 16S rRNA gene fragments. Operational taxonomic units (OTUs) related to Nitrospirae and OP3 MTB, which produce teardrop-shape magnetosomes, were detected only within the OATZ, whereas OTUs related to alphaproteobacterial MTB, which produce equant or elongated magnetite particles, were distributed above the OATZ. These results suggest that magnetofossil morphology can be used to detect past OATZs, and that some MTB lineages can occur ubiquitously in marine sediments rather than being limited within the OATZ. Our results imply that the timing of remanent magnetization acquisition may depend on the inhabiting MTB lineages.

Metal-sulfides are wide-spread in marine benthic habitats. At deep-sea hydrothermal vents, they occur as massive sulfide chimneys formed by mineral precipitation upon mixing of reduced vent fluids with cold oxygenated sea water. Although microorganisms inhabiting actively venting chimneys and utilizing compounds supplied by the venting fluids are well studied, only little is known about microorganisms inhabiting inactive chimneys. In this study, we combined 16S rRNA gene-based community profiling of sulfide chimneys from the Manus Basin (SW Pacific) with radiometric dating, metagenome (n = 4) and metaproteome (n = 1) analyses. Our results shed light on potential lifestyles of yet poorly characterized bacterial clades colonizing inactive chimneys. These include sulfate-reducing Nitrospirae and sulfide-oxidizing Gammaproteobacteria dominating most of the inactive chimney communities. Our phylogenetic analysis attributed the gammaproteobacterial clades to the recently described Woeseiaceae family and the SSr-clade found in marine sediments around the world. Metaproteomic data identified these Gammaproteobacteria as autotrophic sulfide-oxidizers potentially facilitating metal-sulfide dissolution via extracellular electron transfer. Considering the wide distribution of these gammaproteobacterial clades in marine environments such as hydrothermal vents and sediments, microbially accelerated neutrophilic mineral oxidation might be a globally relevant process in benthic element cycling and a considerable energy source for carbon fixation in marine benthic habitats.

Lakes of meltwater in the Artic have become one of the transforming landscape changes under global warming. We herein compared microbial communities between sediments and bank soils at an arctic lake post land submergence using geochemistry, 16S rRNA amplicons, and metagenomes. The results obtained showed that each sample had approximately 2,609 OTUs on average and shared 1,716 OTUs based on the 16S rRNA gene V3-V4 region. Dominant phyla in sediments and soils included Proteobacteria, Acidobacteria, Actinobacteria, Gemmatimonadetes, and Nitrospirae; sediments contained a unique phylum, Euryarchaeota, with the phylum Thaumarchaeota being primarily present in bank soils. Among the top 35 genera across all sites, 17 were more abundant in sediments, while the remaining 18 were more abundant in bank soils; seven out of the top ten genera across all sites were only from sediments. A redundancy analysis separated sediment samples from soil samples based on the components of nitrite and ammonium. Metagenome results supported the role of nitrite because most of the genes for denitrification and methane metabolic genes were more abundant in sediments than in soils, while the abundance of phosphorus-utilizing genes was similar and, thus, was not a significant explanatory factor. We identified several modules from the global networks of OTUs that were closely related to some geochemical factors, such as pH and nitrite. Collectively, the present results showing consistent changes in geochemistry, microbiome compositions, and functional genes suggest an ecological mechanism across molecular and community levels that structures microbiomes post land submergence.

The study reports diversity in nitrifying microbial enrichments from low (0.5-5‰) and high (18-35‰) saline ecosystems. Microbial community profiling of AOB and NOB enrichments were analysed by sequencing 16S rRNA and were processed using Mothur pipeline. The α-diversity indices showed the richness of nitrifying bacterial consortia from the high saline environment and were clustering based on the source of the sample. AOB and NOB enrichments from both the environments showed diverse lineages of phyla distributed in both groups with 38 and 34 phyla from low saline and 53 and 40 phyla in high saline sources respectively. At class level α and ϒ-Proteobacteria were found to be more dominant in both the enrichments. AOB and NOBs in enrichments from low saline environments were dominated by Nitrosomonadaceae, Gallionellaceae (Nitrotoga spp.) and Ectothiorhodospiraeceae and Nitrospira respectively. Though Chromatiaceae were present in both AOB and NOB enrichments Nitrosoglobus and Nitrosococcus dominated the AOB while NOB was dominated by uncultured genera, while Rhizobiales were found in both the enrichments. AOB and NOBs in enrichments from high saline environments were dominated by Nitrospira-like AOBs, Nitrosomonas and Nitrosococcus genera; while AOA group included Nitrosopumilus and Nitrososphaeraea genera comprising and Nitrospirae respectively. The majority of the genera obtained in both the salinities were found to be either uncultured or unclassified groups. Results of the study suggest that the AOB and NOB consortia have unique and diverse microbes in each of the enrichments, capable of functioning in aquaculture systems practiced at different salinities (0-60ppt).

The southeast Andaman Sea 52-m off the west coast of Phang Nga province, Thailand, is located in the Indian Ocean, representing a hotspot for marine biodiversity of the world. This study utilized metagenomics combined 16S rRNA gene (V3–V4) sequencing, and firstly revealed the microbiota and their metabolism potentials of this site at an epipelagic depth (150-m depth, TC150M), including comparison with its pelagic depth (30-m depth, TC30M) as well as other nearby Thailand and global ocean sites. Between TC150M and TC30M, the TC150M microbial metagenomics was an eight-fold higher, and the microbiota comprised, for examples more abundant Bacteroidetes while fewer Proteobacteria, than the TC30M. The microbial metabolic potentials of the TC150M were statistically higher in replication repair and metabolisms of amino acids, lipids, nucleotides, and xenobiotics biodegradation, etc. Following comparative microbiota analyses between three Andaman Sea sites and two Gulf of Thailand sites, the relatively great proportions of Bacteroidetes, Nitrospirae, Gemmatimonadetes, and Chlorobi characterized the southeast Andaman Sea. Nevertheless, the microbiota representing Thailand marine sites remained distinguished from the global ocean sites where beta diversities were close. Thai maritime sites showed proportionally higher Proteobacteria, Bacteroides, Nitrospirae, Gemmatimonadetes, and Chlorobi. Thus, the Thai marine microbiota database helps better understand our global ocean microbiota and microbial metabolic potentials. Here, the microbial metabolism potentials between Thailand and the global ocean sites of relatively close microbiota databases encompose the similar functions yet in statistically different frequencies. Our research provided the first preliminary marine microbiome comparison between the epipelagic and pelagic sea levels of the southeast Andaman Sea, Thailand.

An innovative investigation was undertaken into the abundance and diversity of high antibiotic-resistant bacteria in aquaculture waters in Shandong Province, China, through cumulation incubation, PCR amplification of 16S rDNA, and high-throughput sequencing. The results showed that Vibrio, Bacillus, Vagococcus, Acinetobacter, Shewanella, Psychrobacter, Lactococcus, Enterococcus, Marinimonus and Myroids were abundant in the aquaculture waters, whereas other phylum including Actinobacteria, Deinococcus-Thermus, Omnitrophica and Nitrospirae had relatively lower abundance. Our studies revealed the presence of different bacteria in different locations in the aquaculture waters, most of which were resistant to multiple antibiotics. That is, the same microbial species from the same aquaculture wastewater can resist different antibiotics. Altogether, a considerable portion of the microbial community were found to be multi-drug resistant. It is essential that the spread of the antibiotic-resistant bacteria is controlled so that the distribution of antibiotic resistance genes to other environments is avoided. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02656-4.

Empirical evidence supports selection of soil microbial communities by edaphic properties across large spatial scales; however, less is known at smaller spatial scales. The goal of this research was to evaluate relationships between ecosystem characteristics and bacterial community structure/function at broad taxonomic resolutions in soils across small spatial scales. We employed 16S rRNA gene sequencing, community-level physiological profiling and soil chemical analysis to address this goal. We found weak relationships between gradients in soil characteristics and community structure/function. Specific operational taxonomic units did not respond to edaphic variation, but Acidobacteria, Bacteroidetes and Nitrospirae shifted their relative abundances. High metabolic diversity within the bacterial communities was observed despite general preference of Tween 40/80. Carbon metabolism patterns suggest dominance of functional specialists at our times of measurement. Pairwise comparison of carbon metabolism patterns indicates high levels of functional redundancy. Lastly, at broad taxonomic scales, community structure and function weakly covary with edaphic properties. This evidence suggests that stochasticity or unmeasured environmental gradients may be influential in bacterial community assembly in soils at small spatial scales.

13 páginas.- 4 figuras.- 3 tablas.- 60 referencias, The microbiota associated with vermiculations from karst caves is largely unknown. Vermiculations are enigmatic deposits forming worm-like patterns on cave walls all over the world. They represent a precious focus for geomicrobiological studies aimed at exploring both the microbial life of these ecosystems and the vermiculation genesis. This study comprises the first approach on the microbial communities thriving in Pertosa-Auletta Cave (southern Italy) vermiculations by next-generation sequencing. The most abundant phylum in vermiculations was Proteobacteria, followed by Acidobacteria > Actinobacteria > Nitrospirae > Firmicutes > Planctomycetes > Chloroflexi > Gemmatimonadetes > Bacteroidetes > Latescibacteria. Numerous less-represented taxonomic groups (< 1%), as well as unclassified ones, were also detected. From an ecological point of view, all the groups co-participate in the biogeochemical cycles in these underground environments, mediating oxidation-reduction reactions, promoting host rock dissolution and secondary mineral precipitation, and enriching the matrix in organic matter. Confocal laser scanning microscopy and field emission scanning electron microscopy brought evidence of a strong interaction between the biotic community and the abiotic matrix, supporting the role of microbial communities in the formation process of vermiculations., Open access funding provided by Università degli Studi di Salerno within the CRUI-CARE Agreement. This work was supported by Musei Integrati dell’Ambiente Foundation, by the Spanish project MINECO [CGL2016-75590-P] with European Regional Development Fund and by University of Salerno [ORSA197159].

Term heterotypic synonym refers to different names have been associated with different type strains, however from the opinion of a bacteriologist, different names belongs to the same taxon and term subspecies refers to strains and genetically close organisms that were diverging phenotypically. In this study, sequenced and publicly available genomes in the Edgar 2.0 server were carefully analysed and based on high (>98 %) amino acid identity value, synonyms were putatively identified. The 16S rRNA gene sequence of those species were used for the construction of maximum likelihood based phylogenetic trees to infer the genetic closeness or distance by examining the tree topology and clustering of the organisms within clades. They were further subjected to overall genome related indices like digital DNA-DNA hybridization, average nucleotide identity to confirm the presence of synonyms or subspecies with phenotypic data support. The outcome of this polyphasic taxonomic re-analysis was identification of 40 later heterotypic synonyms and 13 subspecies spread over phylumActinobacteria,Bacteroidetes,Firmicutes,Nitrospirae,ProteobacteriaandThermotogaeand in domainArchaea.

Parys Mountain or Mynydd Parys (Isle of Anglesey, United Kingdom) is a mine-impacted environment, which accommodates a variety of acidophilic organisms. Our previous research of water and sediments from one of the surface acidic streams showed a high proportion of archaea in the total microbial community. To understand the spatial distribution of archaea, we sampled cores (0–20 cm) of sediment and conducted chemical analyses and taxonomic profiling of microbiomes using 16S rRNA gene amplicon sequencing in different core layers. The taxonomic affiliation of sequencing reads indicated that archaea represented between 6.2 and 54% of the microbial community at all sediment depths. Majority of archaea were associated with the order Thermoplasmatales, with the most abundant group of sequences being clustered closely with the phylotype B_DKE, followed by “E-plasma,” “A-plasma,” other yet uncultured Thermoplasmatales with Ferroplasma and Cuniculiplasma spp. represented in minor proportions. Thermoplasmatales were found at all depths and in the whole range of chemical conditions with their abundance correlating with sediment Fe, As, Cr, and Mn contents. The bacterial microbiome component was largely composed in all layers of sediment by members of the phyla Proteobacteria, Actinobacteria, Nitrospirae, Firmicutes, uncultured Chloroflexi (AD3 group), and Acidobacteria. This study has revealed a high abundance of Thermoplasmatales in acid mine drainage-affected sediment layers and pointed at these organisms being the main contributors to carbon, and probably to iron and sulfur cycles in this ecosystem.

The gene pairhgcABis essential for microbial mercury methylation. Our understanding of its abundance and diversity in nature is rapidly evolving. In this study we developed a new broad-range primer set forhgcAB, plus an expandedhgcABreference library, and used these to characterize Hg-methylating communities from diverse environments. We applied this new Hg-methylator database to assign taxonomy tohgcAsequences from clone, amplicon, and metagenomic datasets. We evaluated potential biases introduced in primer design, sequence length, and classification, and suggest best practices for studying Hg-methylator diversity. Our study confirms the emerging picture of an expanded diversity of HgcAB-encoding microbes in many types of ecosystems, with abundant putative mercury methylatorsNitrospiraeandChloroflexiin several new environments including salt marsh and peat soils. Other common microbes encoding HgcAB includedPhycisphaerae, Aminicenantes, Spirochaetes, andElusimicrobia. Gene abundance data also corroborate the important role of two “classic” groups of methylators (DeltaproteobacteriaandMethanomicrobia) in many environments, but generally show a scarcity ofhgcAB+Firmicutes. The new primer set was developed to specifically targethgcABsequences found in nature, reducing degeneracy and providing increased sensitivity while maintaining broad diversity capture. We evaluated mock communities to confirm primer improvements, including culture spikes to environmental samples with variable DNA extraction and PCR amplification efficiencies. For select sites, this new workflow was combined with direct high-throughputhgcABsequencing. ThehgcABdiversity generated by direct amplicon sequencing confirmed the potential for novel Hg-methylators previously identified using metagenomic screens. A new phylogenetic analysis using sequences from freshwater, saline, and terrestrial environments showedDeltaproteobacteriaHgcA sequences generally clustered among themselves, while metagenome-resolved HgcA sequences in other phyla tended to cluster by environment, suggesting horizontal gene transfer into many clades. HgcA from marine metagenomes often formed distinct subtrees from those sequenced from freshwater ecosystems. Overall the majority of HgcA sequences branch from a cluster of HgcAB fused proteins related toThermococci, Atribacteria(candidate division OP9),Aminicenantes(OP8), andChloroflexi. The improved primer set and library, combined with direct amplicon sequencing, provide a significantly improved assessment of the abundance and diversity ofhgcAB+ microbes in nature.Contribution to the Field StatementThe gene pairhgcABis essential for microbial production of the neurotoxin methylmercury. In recent years these genes have been used as biomarkers to determine the potential of a microbiome to generate methylmercury via PCR amplification using degenerate primers from several research groups. However, improved techniques for capturinghgcABdiversity are necessary for identifying the major environmental producers of the neurotoxin as well as the expanding diversity of novel putative methylators, and the genes’ evolutionary history. The work described herein advanceshgcABdetection in environmental samples through an updated primer set coupled with a direct high-throughput sequencing method that enables broader diversity capture. We provide an expandedhgcABsequence reference library that allows for more sensitive and robust estimations of Hg-methylator diversity and potential for MeHg generation in the environment. ThehgcABdiversity generated by high-throughput sequencing confirms the potential for novel Hg-methylators previously only identified using metagenomic screens. This study provides a significantly improved assessment of the abundance and diversity ofhgcAB+ microbes in nature. By expanding our understanding of the microbial metabolic clades associated with mercury methylation, this work improves our ability to predict environmental conditions that drive production and accumulation of the neurotoxin in aquatic ecosystems.

To get insights into microbial diversity and biogeochemical processes in the terrestrial deep subsurface aquifer, we sequenced the metagenome of artesian water collected at a 2.8 km deep oil exploration borehole 5P in Western Siberia, Russia. We obtained 71 metagenome-assembled genomes (MAGs), altogether comprising 93% of the metagenome. Methanogenic archaea accounted for about 20% of the community and mostly belonged to hydrogenotrophic Methanobacteriaceae; acetoclastic and methylotrophic lineages were less abundant. ANME archaea were not found. The most numerous bacteria were the Firmicutes, Ignavibacteriae, Deltaproteobacteria, Chloroflexi, and Armatimonadetes. Most of the community was composed of anaerobic heterotrophs. Only six MAGs belonged to sulfate reducers. These MAGs accounted for 5% of the metagenome and were assigned to the Firmicutes, Deltaproteobacteria, Candidatus Kapabacteria, and Nitrospirae. Organotrophic bacteria carrying cytochrome c oxidase genes and presumably capable of aerobic respiration mostly belonged to the Chloroflexi, Ignavibacteriae, and Armatimonadetes. They accounted for 13% of the community. The first complete closed genomes were obtained for members of the Ignavibacteriae SJA-28 lineage and the candidate phylum Kapabacteria. Metabolic reconstruction of the SJA-28 bacterium, designated Candidatus Tepidiaquacella proteinivora, predicted that it is an anaerobe growing on proteinaceous substrates by fermentation or anaerobic respiration. The Ca. Kapabacteria genome contained both the sulfate reduction pathway and cytochrome c oxidase. Presumably, the availability of buried organic matter of Mesozoic marine sediments, long-term recharge of the aquifer with meteoric waters and its spatial heterogeneity provided the conditions for the development of microbial communities, taxonomically and functionally more diverse than those found in oligotrophic underground ecosystems.

Made available in DSpace on 2020-12-12T02:15:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-08-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The objectives of this study were to analyze the difference in ways in which metals polluting Brazilian port areas influence bacterial communities and the selection of resistant strains. The hypothesis tested was that port areas would have microbial communities significantly different from a pristine area, mainly due to a greater load of metals found in these areas. Sediment samples were collected in two port areas (Santos and São Sebastião) and one pristine area (Ubatuba). Total DNA was extracted and MiSeq sequencing was performed. A hundred strains were isolated from the same samples and were tested for metal resistance. The community composition was similar in the two port regions, but differed from the pristine area. Microbial diversity was significantly lower in the port areas. The phyla Proteobacteria, Cyanobacteria, and Thermodesulfobacteria exhibited positive correlations with copper and zinc concentrations. Chloroflex, Nitrospirae, Planctomycetes, and Chlorobi exhibited negative correlations with copper, chromium, and zinc. Cr and Zn had higher concentrations at port areas and were responsible to select more metal-resistant strains. Some genera were found to be able to easily develop metal resistance. The most isolated genera were Bacillus, Vibrio, and Pseudomonas. This type of study can illustrate, even in very complex natural environments, the influence of pollution on the community as a whole and the consequences of these changes. Department of Biochemistry and Microbiology School of Biology São Paulo State University – Rio Claro Campus (UNESP Rio Claro), Av. 24 A, 1515 - Jardim Vila Bela School of Biosciences São Paulo State University – São Vicente Campus (UNESP São Vicente), Praça Infante Dom Henrique, s/n Department of Chemistry Center for Exact Sciences and Technology Federal University of Sergipe – São Cristóvão Campus (UFS São Cristóvão), Cidade Universitária Prof. José Aloísio de Campos Rosa Elze School of Technological Sciences Federal University of Alfenas (UNIFAL-MG), Rodovia Aurélio Vilela, n 11.999 Cidade Universitária Department of Biochemistry and Microbiology School of Biology São Paulo State University – Rio Claro Campus (UNESP Rio Claro), Av. 24 A, 1515 - Jardim Vila Bela School of Biosciences São Paulo State University – São Vicente Campus (UNESP São Vicente), Praça Infante Dom Henrique, s/n FAPESP: 2015/21020-5 CAPES: 88882.434109/2019-01

Background Avene Thermal Spring Water (TSW) exhibits therapeutic properties in the treatment of skin pathologies. Arising from a dolomitic aquifer system, its physico-chemical properties are well-established and its bacteriological quality regularly monitored. The microbiota of this aquifer have been characterized. Objectives We aimed to describe the structure of the bacterial community inhabiting the deep aquifer and to examine its dynamics over time. Methods The Avene TSW was collected at the catchment point and filtered through 0.1 µm pore size filters. The sampling was carried out every 3 months to generate a 4-year time series. The DNA extracted from filters was analysed using high-throughput 16S rRNA gene amplicon sequencing, and the microorganisms and their contribution were characterized by the taxonomic assignment of sequence variants generated from each sample. Results Bacteria were distributed into 39 phyla. Nitrospirae and Proteobacteria were the most prevalent, accounting for 38% and 23% of the total community on average, respectively. A stable pattern was observed throughout the study. A few bacterial species were always detected, forming a core community of likely chemolithoautotrophic organisms which might use energy sources and nutrients produced from water-bedrock interactions. Most of the species were distantly related to organisms described to date. Conclusions Avene TSW provided by the deep aquifer system harbours a unique microbial community, shaped by the physico-chemical characteristics of the deep environment. Its remarkable stability over time has revealed a high level of confinement of the water resource.

We used high‐throughput DNA sequencing methods combined with bio‐geochemical profiles to characterize the internal environment and community structure of the microbiome of the basidiomycete fungus Pisolithus arhizus (Scop.) Rauschert from soils within a geothermal feature of Yellowstone National Park. Pisolithus arhizus is unique in that it forms closed fruiting bodies that sequester visible sulfur within. Fourier transform infrared spectroscopy (FTIR) analysis demonstrates that the P. arhizus fruiting body also concentrates copper, manganese, nickel, and zinc and contains pure granular silica. Gas chromatography‐mass spectrometry (GC‐MS) analysis indicates an environment rich in hydrocarbons. Oxygen probe analysis reveals that zones of up to 4× atmospheric oxygen exist within nanometers of zones of near anoxia. Analysis of microbial community structure using high‐throughput DNA sequencing methods shows that the fruiting body supports a microbiome that reflects the physiochemical environment of the fruiting body. Diversity and richness measures indicate a microbiome that is significantly richer and more diverse than that of the soils in which P. arhizus grows. Further, P. arhizus sporocarps are enriched significantly in Proteobacteria (primarily Burkholderia) Gemmatimonadetes, Bacteroidetes, Verrucomicrobia, Nitrospirae, Elusimicrobia, and Latescibacteria (WS3) while soils are enriched in Actinobacteria (primarily Mycobacterium), Dormibacteraeota (AD3), and Eremiobacteraeota (WPS‐2). Finally, pairwise % similarity comparisons indicate that P. arhizus harbors two lineages that may represent new groups in the candidate phylum radiation (CPR). Together, these results demonstrate that P. arhizus provides a novel environment for microbiome studies and provides for interesting hypotheses regarding the evolution, origins, and functions of symbioses and novel microbes., This work describes the microbiome of the thermophilic fungus Pisolithus arhizus. Pisolithus arhizus creates an energy‐rich island refugium habitat in a thermal soil desert that harbors microbial community that is distinct from parent soils and includes deeply diverging novel lineages. The results demonstrate that P. arhizus provides for interesting hypotheses regarding the evolution, origins, and functions of symbioses and novel microbes.

BackgroundDeep-sea hydrothermal vents are highly productive biodiversity hotspots in the deep ocean supported by chemosynthetic microorganisms. Prominent features of these systems are sulfide chimneys emanating high-temperature hydrothermal fluids. While several studies have investigated the microbial diversity in both active and inactive sulfide chimneys that have been extinct for up to thousands of years, little is known about chimneys that have ceased activity more recently, as well as the microbial succession occurring during the transition from active to inactive chimneys.ResultsGenome-resolved metagenomics was applied to an active and a recently extinct (~ 7 years) sulfide chimney from the 9–10° N hydrothermal vent field on the East Pacific Rise. Full-length 16S rRNA gene and a total of 173 high-quality metagenome assembled genomes (MAGs) were retrieved for comparative analysis. In the active chimney (L-vent), sulfide- and/or hydrogen-oxidizingCampylobacteriaandAquificaewith the potential for denitrification were identified as the dominant community members and primary producers, fixing carbon through the reductive tricarboxylic acid (rTCA) cycle. In contrast, the microbiome of the recently extinct chimney (M-vent) was largely composed of heterotrophs from various bacterial phyla, includingDelta-/Beta-/AlphaproteobacteriaandBacteroidetes.Gammaproteobacteriawere identified as the main primary producers, using the oxidation of metal sulfides and/or iron oxidation coupled to nitrate reduction to fix carbon through the Calvin-Benson-Bassham (CBB) cycle. Further analysis revealed a phylogenetically distinctNitrospiraecluster that has the potential to oxidize sulfide minerals coupled to oxygen and/or nitrite reduction, as well as for sulfate reduction, and that might serve as an indicator for the early stages of chimneys after venting has ceased.ConclusionsThis study sheds light on the composition, metabolic functions, and succession of microbial communities inhabiting deep-sea hydrothermal vent sulfide chimneys. Collectively, microbial succession during the life span of a chimney could be described to proceed from a “fluid-shaped” microbial community in newly formed and actively venting chimneys supported by the oxidation of reductants in the hydrothermal fluid to a “mineral-shaped” community supported by the oxidation of minerals after hydrothermal activity has ceased. Remarkably, the transition appears to occur within the first few years, after which the communities stay stable for thousands of years.

The microbiota of four Antarctic sponges, Dendrilla antarctica, Sphaerotylus antarcticus, Mycale acerata, and Hemigellius pilosus, collected at two South Shetland Islands and at two locations in the Antarctic Peninsula separated by ca. 670 km, were analyzed together with surrounding seawater. We used high throughput sequencing of the V4 region of the 16S rRNA gene common to Bacteria and Archaea to investigate the microbial diversity and community composition. Our study reveals that sponge-associated prokaryote communities are consistently detected within a particular sponge species regardless of the collection site. Their community structure and composition are typical of low microbial abundance (LMA) sponges. We conclude that prokaryote communities from Antarctic sponges are less diverse and differ in their composition compared to those in the water column. Microbiome analysis indicates that Antarctic sponges harbor a strict core consisting of seven OTUs, and a small variable community comprising several tens of OTUs. Two abundant prokaryotes from the variable microbiota that are affiliated to the archaeal and bacterial phyla Thaumarchaeota and Nitrospirae may be involved in the sponge nitrification process and might be relevant components of the nitrogen cycling in Antarctica. The likely generalist nature of dominant microbes and the host-specific structure of symbiont communities suggest that these Antarctic sponges represent different ecological niches for particular microbial enrichments.