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Wasmund K, Pelikan C, Schintlmeister A, Wagner M, Watzka M, Richter A, Bhatnagar S, Noel A, Hubert CRJ, Rattei T, Hofmann T, Hausmann B, Herbold CW, Loy A. Genomic insights into diverse bacterial taxa that degrade extracellular DNA in marine sediments. Nat Microbiol 2021; 6:885-898. [PMID: 34127845 PMCID: PMC8289736 DOI: 10.1038/s41564-021-00917-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 05/07/2021] [Indexed: 12/13/2022]
Abstract
Extracellular DNA is a major macromolecule in global element cycles, and is a particularly crucial phosphorus, nitrogen and carbon source for microorganisms in the seafloor. Nevertheless, the identities, ecophysiology and genetic features of DNA-foraging microorganisms in marine sediments are largely unknown. Here, we combined microcosm experiments, DNA stable isotope probing (SIP), single-cell SIP using nano-scale secondary isotope mass spectrometry (NanoSIMS) and genome-centric metagenomics to study microbial catabolism of DNA and its subcomponents in marine sediments. 13C-DNA added to sediment microcosms was largely degraded within 10 d and mineralized to 13CO2. SIP probing of DNA revealed diverse ‘Candidatus Izemoplasma’, Lutibacter, Shewanella and Fusibacteraceae incorporated DNA-derived 13C-carbon. NanoSIMS confirmed incorporation of 13C into individual bacterial cells of Fusibacteraceae sorted from microcosms. Genomes of the 13C-labelled taxa all encoded enzymatic repertoires for catabolism of DNA or subcomponents of DNA. Comparative genomics indicated that diverse ‘Candidatus Izemoplasmatales’ (former Tenericutes) are exceptional because they encode multiple (up to five) predicted extracellular nucleases and are probably specialized DNA-degraders. Analyses of additional sediment metagenomes revealed extracellular nuclease genes are prevalent among Bacteroidota at diverse sites. Together, our results reveal the identities and functional properties of microorganisms that may contribute to the key ecosystem function of degrading and recycling DNA in the seabed. Using microcosms, stable isotope probing, genome-resolved metagenomics and NanoSIMS, the authors identify diverse bacterial taxa that can degrade extracellular DNA in marine sediments, including ‘Candidatus Izemoplasma’, which encode numerous extracellular nucleases.
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Affiliation(s)
- Kenneth Wasmund
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria. .,Austrian Polar Research Institute, Vienna, Austria. .,Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark.
| | - Claus Pelikan
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria.,Austrian Polar Research Institute, Vienna, Austria
| | - Arno Schintlmeister
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria.,Large-Instrument Facility for Environmental and Isotope Mass Spectrometry, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Michael Wagner
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria.,Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark.,Large-Instrument Facility for Environmental and Isotope Mass Spectrometry, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Margarete Watzka
- Division of Terrestrial Ecosystem Research, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Andreas Richter
- Austrian Polar Research Institute, Vienna, Austria.,Division of Terrestrial Ecosystem Research, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Srijak Bhatnagar
- Geomicrobiology Group, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Amy Noel
- Geomicrobiology Group, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Casey R J Hubert
- Geomicrobiology Group, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Thomas Rattei
- Division of Computational Systems Biology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Thilo Hofmann
- Division of Environmental Geosciences, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Bela Hausmann
- Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna, Vienna, Austria.,Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
| | - Craig W Herbold
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Alexander Loy
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria.,Austrian Polar Research Institute, Vienna, Austria.,Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna, Vienna, Austria
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Diversity, ecology and evolution of Archaea. Nat Microbiol 2020; 5:887-900. [PMID: 32367054 DOI: 10.1038/s41564-020-0715-z] [Citation(s) in RCA: 193] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 03/30/2020] [Indexed: 12/23/2022]
Abstract
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.
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Zhao R, Summers ZM, Christman GD, Yoshimura KM, Biddle JF. Metagenomic views of microbial dynamics influenced by hydrocarbon seepage in sediments of the Gulf of Mexico. Sci Rep 2020; 10:5772. [PMID: 32238866 PMCID: PMC7113308 DOI: 10.1038/s41598-020-62840-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 03/16/2020] [Indexed: 12/12/2022] Open
Abstract
Microbial cells in the seabed are thought to persist by slow population turnover rates and extremely low energy requirements. External stimulations such as seafloor hydrocarbon seeps have been demonstrated to significantly boost microbial growth; however, the microbial community response has not been fully understood. Here we report a comparative metagenomic study of microbial response to natural hydrocarbon seeps in the Gulf of Mexico. Subsurface sediments (10-15 cm below seafloor) were collected from five natural seep sites and two reference sites. The resulting metagenome sequencing datasets were analyzed with both gene-based and genome-based approaches. 16S rRNA gene-based analyses suggest that the seep samples are distinct from the references by both 16S rRNA fractional content and phylogeny, with the former dominated by ANME-1 archaea (~50% of total) and Desulfobacterales, and the latter dominated by the Deltaproteobacteria, Planctomycetes, and Chloroflexi phyla. Sulfate-reducing bacteria (SRB) are present in both types of samples, with higher relative abundances in seep samples than the references. Genes for nitrogen fixation were predominantly found in the seep sites, whereas the reference sites showed a dominant signal for anaerobic ammonium oxidation (anammox). We recovered 49 metagenome-assembled genomes and assessed the microbial functional potentials in both types of samples. By this genome-based analysis, the seep samples were dominated by ANME-1 archaea and SRB, with the capacity for methane oxidation coupled to sulfate reduction, which is consistent with the 16S rRNA-gene based characterization. Although ANME-1 archaea and SRB are present in low relative abundances, genome bins from the reference sites are dominated by uncultured members of NC10 and anammox Scalindua, suggesting a prevalence of nitrogen transformations for energy in non-seep pelagic sediments. This study suggests that hydrocarbon seeps can greatly change the microbial community structure by stimulating nitrogen fixation, inherently shifting the nitrogen metabolism compared to those of the reference sediments.
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Affiliation(s)
- Rui Zhao
- School of Marine Science and Policy, University of Delaware, Lewes, DE, United States
| | - Zarath M Summers
- Corporate Strategic Research, ExxonMobil Research and Engineering, Annandale, NJ, United States
| | - Glenn D Christman
- School of Marine Science and Policy, University of Delaware, Lewes, DE, United States
| | - Kristin M Yoshimura
- School of Marine Science and Policy, University of Delaware, Lewes, DE, United States
| | - Jennifer F Biddle
- School of Marine Science and Policy, University of Delaware, Lewes, DE, United States.
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Wasmund K, Mußmann M, Loy A. The life sulfuric: microbial ecology of sulfur cycling in marine sediments. ENVIRONMENTAL MICROBIOLOGY REPORTS 2017; 9:323-344. [PMID: 28419734 PMCID: PMC5573963 DOI: 10.1111/1758-2229.12538] [Citation(s) in RCA: 162] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Almost the entire seafloor is covered with sediments that can be more than 10 000 m thick and represent a vast microbial ecosystem that is a major component of Earth's element and energy cycles. Notably, a significant proportion of microbial life in marine sediments can exploit energy conserved during transformations of sulfur compounds among different redox states. Sulfur cycling, which is primarily driven by sulfate reduction, is tightly interwoven with other important element cycles (carbon, nitrogen, iron, manganese) and therefore has profound implications for both cellular- and ecosystem-level processes. Sulfur-transforming microorganisms have evolved diverse genetic, metabolic, and in some cases, peculiar phenotypic features to fill an array of ecological niches in marine sediments. Here, we review recent and selected findings on the microbial guilds that are involved in the transformation of different sulfur compounds in marine sediments and emphasise how these are interlinked and have a major influence on ecology and biogeochemistry in the seafloor. Extraordinary discoveries have increased our knowledge on microbial sulfur cycling, mainly in sulfate-rich surface sediments, yet many questions remain regarding how sulfur redox processes may sustain the deep-subsurface biosphere and the impact of organic sulfur compounds on the marine sulfur cycle.
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Affiliation(s)
- Kenneth Wasmund
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, Research Network “Chemistry meets Microbiology”University of ViennaAlthanstrasse 14ViennaA‐1090Austria
- Austrian Polar Research InstituteViennaAustria
| | - Marc Mußmann
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, Research Network “Chemistry meets Microbiology”University of ViennaAlthanstrasse 14ViennaA‐1090Austria
| | - Alexander Loy
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, Research Network “Chemistry meets Microbiology”University of ViennaAlthanstrasse 14ViennaA‐1090Austria
- Austrian Polar Research InstituteViennaAustria
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Archaeal Diversity and CO 2 Fixers in Carbonate-/Siliciclastic-Rock Groundwater Ecosystems. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2017; 2017:2136287. [PMID: 28694737 PMCID: PMC5485487 DOI: 10.1155/2017/2136287] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 02/22/2017] [Accepted: 04/18/2017] [Indexed: 11/18/2022]
Abstract
Groundwater environments provide habitats for diverse microbial communities, and although Archaea usually represent a minor fraction of communities, they are involved in key biogeochemical cycles. We analysed the archaeal diversity within a mixed carbonate-rock/siliciclastic-rock aquifer system, vertically from surface soils to subsurface groundwater including aquifer and aquitard rocks. Archaeal diversity was also characterized along a monitoring well transect that spanned surface land uses from forest/woodland to grassland and cropland. Sequencing of 16S rRNA genes showed that only a few surface soil-inhabiting Archaea were present in the groundwater suggesting a restricted input from the surface. Dominant groups in the groundwater belonged to the marine group I (MG-I) Thaumarchaeota and the Woesearchaeota. Most of the groups detected in the aquitard and aquifer rock samples belonged to either cultured or predicted lithoautotrophs (e.g., Thaumarchaeota or Hadesarchaea). Furthermore, to target autotrophs, a series of 13CO2 stable isotope-probing experiments were conducted using filter pieces obtained after filtration of 10,000 L of groundwater to concentrate cells. These incubations identified the SAGMCG Thaumarchaeota and Bathyarchaeota as groundwater autotrophs. Overall, the results suggest that the majority of Archaea on rocks are fixing CO2, while archaeal autotrophy seems to be limited in the groundwater.
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Abstract
The diversity of the genetic code systems used by microbes on earth is yet to be elucidated. It is known that certain methanogenic archaea employ an alternative system for cysteine (Cys) biosynthesis and encoding; tRNACys is first acylated with phosphoserine (Sep) by O-phosphoseryl-tRNA synthetase (SepRS) and then converted to Cys-tRNACys by Sep-tRNA:Cys-tRNA synthase (SepCysS). In this study, we searched all genomic and metagenomic protein sequence data in the Integrated Microbial Genomes (IMG) system and at the NCBI to reveal new clades of SepRS and SepCysS proteins belonging to diverse archaea in the four major groups (DPANN, Euryarchaeota, TACK, and Asgard) and two groups of bacteria (“Candidatus Parcubacteria” and Chloroflexi). Bacterial SepRS and SepCysS charged bacterial tRNACys species with cysteine in vitro. Homologs of SepCysE, a scaffold protein facilitating SepRS⋅SepCysS complex assembly in Euryarchaeota class I methanogens, are found in a few groups of TACK and Asgard archaea, whereas the C-terminally truncated homologs exist fused or genetically coupled with diverse SepCysS species. Investigation of the selenocysteine (Sec)- and pyrrolysine (Pyl)-utilizing traits in SepRS-utilizing archaea and bacteria revealed that the archaea carrying full-length SepCysE employ Sec and that SepRS is often found in Pyl-utilizing archaea and Chloroflexi bacteria. We discuss possible contributions of the SepRS-SepCysS system for sulfur assimilation, methanogenesis, and other metabolic processes requiring large amounts of iron-sulfur enzymes or Pyl-containing enzymes. Comprehensive analyses of all genomic and metagenomic protein sequence data in public databases revealed the distribution and evolution of an alternative cysteine-encoding system in diverse archaea and bacteria. The finding that the SepRS-SepCysS-SepCysE- and the selenocysteine-encoding systems are shared by the Euryarchaeota class I methanogens, the Crenarchaeota AK8/W8A-19 group, and an Asgard archaeon suggests that ancient archaea may have used both systems. In contrast, bacteria may have obtained the SepRS-SepCysS system from archaea. The SepRS-SepCysS system sometimes coexists with a pyrrolysine-encoding system in both archaea and bacteria. Our results provide additional bioinformatic evidence for the contribution of the SepRS-SepCysS system for sulfur assimilation and diverse metabolisms which require vast amounts of iron-sulfur enzymes and proteins. Among these biological activities, methanogenesis, methylamine metabolism, and organohalide respiration may have local and global effects on earth. Taken together, uncultured bacteria and archaea provide an expanded record of the evolution of the genetic code.
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