Biology subjects

Tyson, G. W.

Publications and source records attributed to Tyson, G. W..

17 recordsLinked to original sources

bioRxiv2026

Reversible fixation of microbial cells for targeted genomics

Phylogeny- or activity-based fluorescent labelling of microorganisms coupled with fluorescence activated cell sorting (FACS) is a powerful approach to rapidly isolate cells of interest from complex communities for targeted genomics. However, the method has not been widely adopted because standard paraformaldehyde or ethanol fixation procedures hamper nucleic acid recovery and/or long-term sample storage. Here, we present dithiobis(succinimidyl propionate) (DSP) as a reversible fixative for microbial cells that enables fluorescence imaging and DNA extraction and amplification for sequencing. DSP fixation is compatible with widely used fluorescence in situ hybridization (FISH) approaches and bioorthogonal non-canonical amino acid tagging, and can be applied to diverse sample types, where it consistently performed as well as paraformaldehyde. Furthermore, high-quality genomes were obtained from individual and multiple bacterial cells selectively extracted from complex samples using FISH-FACS. Thus, DSP is a dual-use fixative for microbiome imaging and sequencing, improving targeted microbial genomics.

microbiology↗

bioRxiv2026

Potential for metal-coupled methane oxidation by Candidatus Methanocomedenaceae in coastal sediments

Anaerobic methanotrophic (ANME) archaea are important players in the microbial methane cycle, mitigating methane emissions from anoxic environments. ANME are found ubiquitously in methane-rich sediments, where they can couple anaerobic methane oxidation (AOM) to different electron acceptors such as sulfate, metal oxides, and natural organic matter (NOM). However, we still lack understanding of the geochemical niches and preferred metabolic pathways of most ANME subclades. Here, we investigated the genomic potential and ecophysiology of ANME-2a with respect to metal-dependent AOM in brackish metal-rich coastal sediments. We assembled several high-quality ANME MAGs from subclades with high strain heterogeneity and analyzed the genomic potential for metal-AOM. Additionally, we monitored long-term enrichments with various electron acceptors from the same sediments. Ultimately, we recovered 8 novel genomes of ANME-2a that clustered with an uncharacterized genus with only 2 representatives in public databases for which we propose the name Candidatus Methanoborealis. The analysis of the MAGs showed two different clusters within this genus; one comprising of MAGs from the Baltic Sea that showed high potential for extracellular electron transfer (EET) required for metal-AOM, and another cluster form more diverse environments with less EET potential. The Baltic Sea Ca. Methanoborealis were the only canonical methanotrophs in the incubations during active methane oxidation and metal reduction. Our results contribute to the understanding of the phylogenomic and metabolic diversity in ANME subclades, which will help to further characterize novel ANME lineages from complex sediment samples.

microbiology↗

bioRxiv2025

Carbon monoxide metabolism in freshwater anaerobic methanotrophic archaea

Anaerobic methanotrophic archaea mitigate methane emissions in anoxic environments as key members of the biological methane filter. Despite their ecological significance, physiology of anaerobic methanotrophs remains poorly understood. Here, we demonstrate that the freshwater methanotroph Candidatus Methanoperedens BLZ2 prefers carbon monoxide (CO) over methane as an electron donor. In the absence of respiratory nitrate, CO oxidation led to acetogenesis and methanogenesis with rates comparable to methane oxidation. The circularized genome of Ca. M. BLZ2 encodes six Ni-dependent carbon monoxide dehydrogenases (CODHs), three of which were highly expressed. Furthermore, we identified a 156-kbp mobile genetic element carrying central metabolic gene clusters, including two additional, highly expressed CODHs. CODH genes were widespread in Methanoperedenaceae and showed diverse evolutionary affiliations, including Methanocomedenaceae anaerobic methanotrophs and bacterial lineages. These findings highlight a novel metabolism and genome plasticity in anaerobic methanotrophs challenging their classification as obligate methanotrophs and their ecological role in anoxic carbon cycling.

microbiology↗

bioRxiv2025

Mobile genetic elements that shape microbial diversity and functions inthawing permafrost soils

The worlds ecosystems are shaped by microbiota. Their niches and their impacts depend on functional profiles influenced by gene gains and losses. While culture-based experiments demonstrate that mobile genetic elements (MGEs) can mediate gene flux, quantitative field data on the rates and impacts of MGE activity remains scarce. Here we leverage large-scale soil meta-omic data to develop and apply analytics for studying MGEs in complex natural systems. In our model permafrost-thaw ecosystem, Stordalen Mire, we identify [~]2.1 million MGE recombinases across 89 microbial phyla to assess ecological distributions, affected functions, past mobility, and current activity. This revealed MGEs shaping natural genetic diversity via differential impacts on major phyla; affecting a wide range of functions, including diverse regulatory and metabolic genes affecting carbon flux and nutrient cycling; and moving at rates that should significantly influence the realized functional profiles of natural microbiomes. These findings and this systematic meta-omic framework open new avenues to better investigate MGE diversity, activity, mobility, and impacts in nature.

microbiology↗

bioRxiv2025

Stable states in an unstable landscape: microbial resistance at the front line of climate change

Microbiome responses to warming may amplify or ameliorate terrestrial carbon loss and thus are a critical unknown in predicting climate outcomes. Because the rapid thaw of permafrost peatlands makes a very large store of soil carbon available to microbial metabolism, understanding microbiome dynamics in these systems is particularly urgent. We quantified microbial warming response over seven years across three habitats in a thawing permafrost peatland, using large-scale multi-omics data. We integrated analyses of organisms (via taxonomy), functions (via metabolic pathways and proteins), and community organization (via network structure and ecological assembly) to deeply characterize response mechanisms. We consistently found a pattern of within-habitat microbiome stability, with virtually no signal of gradual change in the warming period studied. The resistance to change appeared bolstered by habitat-specific dispersal processes and community-level functional redundancy, particularly via versatile carbon generalists. Our findings also reveal key genome-inferred metabolic processes that underlie microbiome stability. Together, our results highlight the importance of understanding the limits of these stabilizing processes and suggest that future research should reorient towards critical habitat transitions.

microbiology↗

bioRxiv2024

Protozoal populations drive system-wide variation in the rumen microbiome

While rapid progress has been made to characterize the bacterial and archaeal populations of the rumen microbiome, insight into how they interact with keystone protozoal species remains elusive. Here, we reveal two distinct rumen community types (RCT-A and RCT-B) that are not strongly associated with host phenotype nor genotype but instead linked to protozoal community patterns. We leveraged a series of multi-omic datasets to show that the dominant Epidinium spp. in animals with RCT-B employ a plethora of fiber-degrading enzymes that present enriched Prevotella spp. a favorable carbon landscape to forage upon. Conversely, animals with RCT-A, dominated by genera Isotricha and Entodinium, harbor a more even distribution of fiber, protein, and amino acid metabolizers, reflected by higher detection of metabolites from both protozoal and bacterial activity. We reveal microbiome variation across key protozoal and bacterial populations is interlinked, which should act as an important consideration for future development of microbiome-based technologies.

microbiology↗

bioRxiv2024

Bin Chicken: targeted metagenomic coassembly for the efficient recovery of novel genomes

Recovery of microbial genomes from metagenomic datasets has provided genomic representation for hundreds of thousands of species from diverse biomes. However, low abundance microorganisms are often missed due to insufficient genomic coverage. Here we present Bin Chicken, an algorithm which substantially improves genome recovery through automated, targeted selection of metagenomes for coassembly based on shared marker gene sequences derived from raw reads. Marker gene sequences that are divergent from known reference genomes can be further prioritised, providing an efficient means of recovering highly novel genomes. Applying Bin Chicken to public metagenomes and coassembling 800 sample-groups recovered 77,562 microbial genomes, including the first genomic representatives of 6 phyla, 41 classes, and 24,028 species. These genomes expand the genomic tree of life and uncover a wealth of novel microbial lineages for further research.

microbiology↗

bioRxiv2024

SingleM and Sandpiper: Robust microbial taxonomic profiles from metagenomic data

Determining the taxonomy and relative abundance of microorganisms in metagenomic data is a foundational problem in microbial ecology. To address the limitations of existing approaches, we developed SingleM, which estimates community composition using conserved regions within universal marker genes. SingleM accurately profiles complex communities of known microbial species, and is the only tool that detects species without genomic representation, even those representing novel phyla. Given SingleMs computational efficiency, we applied it to 248,559 publicly available metagenomes and show that the vast majority of samples from marine, freshwater, sediment and soil environments are dominated by novel species lacking genomic representation (median relative abundance 75.0%). SingleM also provides a way to identify metagenomes for the recovery of novel metagenome-assembled genomes from lineages of interest, and can incorporate user-recovered genomes into its reference database to improve profiling resolution. Quantifying the full diversity of Bacteria and Archaea in metagenomic data shows that microbial genome databases are far from saturated.

microbiology↗

bioRxiv2023

Nitrate-driven anaerobic oxidation of ethane and butane by bacteria

The short-chain gaseous alkanes (ethane, propane and butane; SCGAs) are important components of natural gas, yet our understanding of their fate in environmental systems is poorly understood. Microbially mediated anaerobic oxidation of SCGAs coupled to nitrate reduction has been demonstrated for propane, but is yet to be shown for ethane or butane - despite being energetically feasible. Here we report two independent bacterial enrichments performing anaerobic ethane and butane oxidation, respectively, coupled to nitrate reduction to dinitrogen gas and ammonium. Isotopic 13C-and 15N-labelling experiments, mass and electron balance tests, and metabolite and meta-omics analyses collectively reveal that the recently described propane-oxidising Candidatus Alkanivorans nitratireducens was also responsible for nitrate-dependent anaerobic oxidation of the SCGAs in both these enrichments. The complete genome of this species encodes alkylsuccinate synthase genes for the activation of ethane/butane via fumarate addition. Further substrate range tests confirm Ca. A. nitratireducens is metabolically versatile, being able to degrade ethane, propane and butane under anaerobic conditions. Moreover, our study proves nitrate as an additional electron sink for ethane and butane in anaerobic environments, and for the first time demonstrates the use of the fumarate addition pathway in anaerobic ethane oxidation. These findings significantly contribute to our understanding of microbial metabolism of SCGAs in anaerobic environments.

microbiology↗

bioRxiv2023

Methylotrophy in the Mire: direct and indirect routes for methane production in thawing permafrost

While wetlands are major sources of biogenic methane (CH4), our understanding of resident microbial metabolisms is incomplete, which compromises prediction of CH4 emissions under ongoing climate change. Here, we employed genome-resolved multi-omics to expand our understanding of methanogenesis in the thawing permafrost peatland of Stordalen Mire, in arctic Sweden. In quadrupling the genomic representation of the sites methanogens and examining their encoded metabolisms, we revealed that nearly 20% (72) of the metagenome-assembled genomes (MAGs) encoded potential for methylotrophic methanogenesis. Further, 27% of the transcriptionally active methanogens expressed methylotrophic genes; for Methanosarcinales and Methanobacteriales MAGs, these data indicated use of methylated oxygen compounds (e.g., methanol), while for Methanomassiliicoccales, they primarily implicated methyl sulfides and methylamines. In addition to methanogenic methylotrophy, >1700 bacterial MAGs across 19 phyla encoded anaerobic methylotrophic potential, with expression across 12 phyla. Metabolomic analyses revealed the presence of diverse methylated compounds in the Mire, including some known methylotrophic substrates. Active methylotrophy was observed across all stages of a permafrost thaw gradient in Stordalen, with the most frozen non-methanogenic palsa found to host bacterial methylotrophy, and the partially thawed bog and fully thawed fen seen to house both methanogenic and bacterial methylotrophic activity. Methanogenesis across increasing permafrost thaw is thus revised from sole dominance of hydrogenotrophic production, and the appearance of acetoclastic at full thaw, to consider co-occurrence of methylotrophy throughout. Collectively, these findings indicate that methanogenic and bacterial methylotrophy may be an important and previously underappreciated component of carbon cycling and emissions in these rapidly changing wetland habitats.

microbiology↗

bioRxiv2023

Population ecology and potential biogeochemical impacts of ssDNA and dsDNA soil viruses along a permafrost thaw gradient

Climate change is disproportionately warming northern peatlands, which may release large carbon stores via increased microbial activity. While there are many unknowns about such microbial responses, virus roles are especially poorly characterized with studies to date largely restricted to "bycatch" from bulk metagenomes. Here, we used optimized viral particle purification techniques on 20 samples along a highly contextualized peatland permafrost thaw gradient, extracted and sequenced viral particle DNA using two library kits to capture single-stranded (ssDNA) and double-stranded (dsDNA) virus genomes (40 total viromes), and explored their diversity and potential ecosystem impacts. Both kits recovered similar dsDNA virus numbers, but only one also captured thousands of ssDNA viruses. Combining these data, we explored population-level ecology using genomic representation from 9,560 viral operational taxonomic units (vOTUs); nearly a 4-fold expansion from permafrost-associated soils, and 97% of which were novel when compared against large datasets from soils, oceans, and the human gut. In silico predictions identified putative hosts for 44% (4,149 dsDNA + 17 ssDNA) of the identified vOTUs spanning 2 eukaryotic, 12 archaeal, and 30 bacterial phyla. The recovered vOTUs encoded 1,684 putative auxiliary metabolic genes (AMGs) and other metabolic genes carried by [~]10% of detected vOTUs, of which 46% were related to carbon processing and 644 were novel. These AMGs grouped into five functional categories and 11 subcategories, and nearly half (47%) of the AMGs were involved in carbon utilization. Of these, 112 vOTUs encoded 123 glycoside hydrolases spanning 15 types involved in the degradation of polysaccharides (e.g., cellulose) to monosaccharides (e.g., galactose), or further monosaccharide degradation, which suggests virus involvement in myriad metabolisms including fermentation and central carbon metabolism. These findings expand the scope of viral roles in microbial carbon processing and suggest viruses may be critical for understanding the fate of soil organic carbon in peatlands.

microbiology↗

bioRxiv2022

CheckM2: a rapid, scalable and accurate tool for assessing microbial genome quality using machine learning

Advances in DNA sequencing and bioinformatics have dramatically increased the rate of recovery of microbial genomes from metagenomic data. Assessing the quality of metagenome-assembled genomes (MAGs) is a critical step prior to downstream analysis. Here, we present CheckM2, an improved method of predicting the completeness and contamination of MAGs using machine learning. We demonstrate the effectiveness of CheckM2 on synthetic and experimental data, and show that it outperforms the original version of CheckM in predicting MAG quality. CheckM2 is substantially faster than CheckM and its database can be rapidly updated with new high-quality reference genomes. We show that CheckM2 accurately predicts genome quality for MAGs from novel lineages, even those with sparse genomic representation, or reduced genome size (e.g. symbionts) such as those found in the Patescibacteria and the DPANN superphylum. CheckM2 provides accurate genome quality predictions across the microbial tree of life, giving increased confidence when inferring novel biological conclusions from MAGs.

bioinformatics↗

bioRxiv2021

Comparative genomics reveals electron transfer and syntrophic mechanisms differentiating methanotrophic and methanogenic archaea

The anaerobic oxidation of methane coupled to sulfate reduction is a microbially mediated process requiring a syntrophic partnership between anaerobic methanotrophic (ANME) archaea and sulfate reducing bacteria (SRB). Based on genome taxonomy, ANME lineages are polyphyletic within the phylum Halobacterota, none of which have been isolated in pure culture. Here we reconstruct 28 ANME genomes from environmental metagenomes and flow sorted syntrophic consortia. Together with a reanalysis of previously published datasets, these genomes enable a comparative analysis of all marine ANME clades. We review the genomic features which separate ANME from their methanogenic relatives and identify what differentiates ANME clades. Large multiheme cytochromes and bioenergetic complexes predicted to be involved in novel electron bifurcation reactions are well-distributed and conserved in the ANME archaea, while significant variations in the anabolic C1 pathways exists between clades. Our analysis raises the possibility that methylotrophic methanogenesis may have evolved from a methanotrophic ancestor.

microbiology↗

bioRxiv2020

Diverse Arctic lake sediment microbiota shape methane emission temperature sensitivity

Northern post-glacial lakes are a significant and increasing source of atmospheric carbon (C), largely through ebullition (bubbling) of microbially-produced methane (CH4) from the sediments1. Ebullitive CH4 flux correlates strongly with temperature, suggesting that solar radiation is the primary driver of these CH4 emissions2. However, here we show that the slope of the temperature-CH4 flux relationship differs spatially, both within and among lakes. Hypothesizing that differences in microbiota could explain this heterogeneity, we compared site-specific CH4 emissions with underlying sediment microbial (metagenomic and amplicon), isotopic, and geochemical data across two post-glacial lakes in Northern Sweden. The temperature-associated increase in CH4 emissions was greater in lake middles--where methanogens were more abundant--than edges, and sediment microbial communities were distinct between lake edges and middles. Although CH4 emissions projections are typically driven by abiotic factors1, regression modeling revealed that microbial abundances, including those of CH4-cycling microorganisms and syntrophs that generate H2 for methanogenesis, can be useful predictors of porewater CH4 concentrations. Our results suggest that deeper lake regions, which currently emit less CH4 than shallower edges, could add substantially to overall CH4 emissions in a warmer Arctic with longer ice-free seasons and that future CH4 emission predictions from northern lakes may be improved by accounting for spatial variations in sediment microbiota.

microbiology↗

bioRxiv2020

Lateral gene transfer drives metabolic flexibility in the anaerobic methane oxidising archaeal family Methanoperedenaceae

Anaerobic oxidation of methane (AOM) is an important biological process responsible for controlling the flux of methane into the atmosphere. Members of the archaeal family Methanoperedenaceae (formerly ANME-2d) have been demonstrated to couple AOM to the reduction of nitrate, iron, and manganese. Here, comparative genomic analysis of 16 Methanoperedenaceace metagenome-assembled genomes (MAGs), recovered from diverse environments, revealed novel respiratory strategies acquired through lateral gene transfer (LGT) events from diverse archaea and bacteria. Comprehensive phylogenetic analyses suggests that LGT has allowed members of the Methanoperedenaceae to acquire genes for the oxidation of hydrogen and formate, and the reduction of arsenate, selenate and elemental sulfur. Numerous membrane-bound multi-heme c type cytochrome complexes also appear to have been laterally acquired, which may be involved in the direct transfer of electrons to metal oxides, humics and syntrophic partners. ImportanceAOM by microorganisms limits the atmospheric release of the potent greenhouse gas methane and has consequent importance to the global carbon cycle and climate change modelling. While the oxidation of methane coupled to sulphate by consortia of anaerobic methanotrophic (ANME) archaea and bacteria is well documented, several other potential electron acceptors have also been reported to support AOM. In this study we identify a number of novel respiratory strategies that appear to have been laterally acquired by members of the Methanoperedenaceae as they are absent in related archaea and other ANME lineages. Expanding the known metabolic potential for members of the Methanoperedenaceae provides important insight into their ecology and suggests their role in linking methane oxidation to several global biogeochemical cycles.

microbiology↗

bioRxiv2018

Soil viruses are underexplored players in ecosystem carbon processing

Rapidly thawing permafrost harbors ~30-50% of global soil carbon, and the fate of this carbon remains unknown. Microorganisms will play a central role in its fate, and their viruses could modulate that impact via induced mortality and metabolic controls. Because of the challenges of recovering viruses from soils, little is known about soil viruses or their role(s) in microbial biogeochemical cycling. Here, we describe 53 viral populations (vOTUs) recovered from seven quantitatively-derived (i.e. not multiple-displacement-amplified) viral-particle metagenomes (viromes) along a permafrost thaw gradient. Only 15% of these vOTUs had genetic similarity to publicly available viruses in the RefSeq database, and ~30% of the genes could be annotated, supporting the concept of soils as reservoirs of substantial undescribed viral genetic diversity. The vOTUs exhibited distinct ecology, with dramatically different distributions along the thaw gradient habitats, and a shift from soil-virus-like assemblages in the dry palsas to aquatic-virus-like in the inundated fen. Seventeen vOTUs were linked to microbial hosts (in silico), implicating viruses in infecting abundant microbial lineages from Acidobacteria, Verrucomicrobia, and Deltaproteoacteria, including those encoding key biogeochemical functions such as organic matter degradation. Thirty-one auxiliary metabolic genes (AMGs) were identified, and suggested viral-mediated modulation of central carbon metabolism, soil organic matter degradation, polysaccharide-binding, and regulation of sporulation. Together these findings suggest that these soil viruses have distinct ecology, impact host-mediated biogeochemistry, and likely impact ecosystem function in the rapidly changing Arctic.

microbiology↗

bioRxiv2018

Further expansion of methane metabolism in the Archaea

The recent discovery of key methane-metabolizing genes in the genomes from the archaeal phyla Bathyarchaeota and Verstraetearchaeota has expanded our understanding of the distribution of methane metabolism outside of the phylum Euryarchaeota. Here, we recovered two near-complete crenarchaeotal metagenome-assembled genomes (MAGs) from circumneutral hot springs that contain genes for methanogenesis, including the genes that encode for the key methyl-coenzyme M reductase (MCR) complex. These newly recovered archaea phylogenetically cluster with Geoarchaeota (deep lineage of archaeal order Thermoproteales), and the MCR-encoding genes clustered with the recently reported methanogens within the Verstraetearchaeota. In addition, genes encoding hydroxybutyryl-CoA dehydratase were identified in the newly recovered methanogens, indicating they might carry out the {beta}-oxidation process. Together, our findings further expanded the methane metabolism outside the phylum Euryarchaeota.

microbiology↗