scholarly journals Identification and Genomic Characterization of Two Previously Unknown Magnetotactic Nitrospirae

2021 ◽  
Vol 12 ◽  
Author(s):  
Wensi Zhang ◽  
Yinzhao Wang ◽  
Li Liu ◽  
Yongxin Pan ◽  
Wei Lin
Keyword(s):  
Sulfide Oxidation ◽  
Significant Proportion ◽  
Amino Acid Identity ◽  
Comparative Genomic ◽  
Rrna Gene ◽  
Dissimilatory Sulfate Reduction ◽  
Metabolic Potential ◽  
Sulfur Globules ◽  
Genomic Characterization ◽  
Key Steps

Magnetotactic bacteria (MTB) are a group of microbes that biomineralize membrane-bound, nanosized magnetite (Fe3O4), and/or greigite (Fe3S4) crystals in intracellular magnetic organelle magnetosomes. MTB belonging to the Nitrospirae phylum can form up to several hundreds of Fe3O4 magnetosome crystals and dozens of sulfur globules in a single cell. These MTB are widespread in aquatic environments and sometimes account for a significant proportion of microbial biomass near the oxycline, linking these lineages to the key steps of global iron and sulfur cycling. Despite their ecological and biogeochemical importance, our understanding of the diversity and ecophysiology of magnetotactic Nitrospirae is still very limited because this group of MTB remains unculturable. Here, we identify and characterize two previously unknown MTB populations within the Nitrospirae phylum through a combination of 16S rRNA gene-based and genome-resolved metagenomic analyses. These two MTB populations represent distinct morphotypes (rod-shaped and coccoid, designated as XYR, and XYC, respectively), and both form more than 100 bullet-shaped magnetosomal crystals per cell. High-quality draft genomes of XYR and XYC have been reconstructed, and they represent a novel species and a novel genus, respectively, according to their average amino-acid identity values with respect to available genomes. Accordingly, the names Candidatus Magnetobacterium cryptolimnobacter and Candidatus Magnetomicrobium cryptolimnococcus for XYR and XYC, respectively, were proposed. Further comparative genomic analyses of XYR, XYC, and previously reported magnetotactic Nitrospirae reveal the general metabolic potential of this MTB group in distinct microenvironments, including CO2 fixation, dissimilatory sulfate reduction, sulfide oxidation, nitrogen fixation, or denitrification processes. A remarkably conserved magnetosome gene cluster has been identified across Nitrospirae MTB genomes, indicating its putative important adaptive roles in these bacteria. Taken together, the present study provides novel insights into the phylogenomic diversity and ecophysiology of this intriguing, yet poorly understood MTB group.

scholarly journals Genomic and Metabolic Insights into Two Novel Thiothrix Species from Enhanced Biological Phosphorus Removal Systems

2020 ◽  
Vol 8 (12) ◽  
pp. 2030
Author(s):  
Andrey V. Mardanov ◽  
Eugeny V. Gruzdev ◽  
Dmitry D. Smolyakov ◽  
Tatyana S. Rudenko ◽  
Alexey V. Beletsky ◽  
...  
Keyword(s):  
Phosphorus Removal ◽  
Tricarboxylic Acid Cycle ◽  
Sulfide Oxidation ◽  
Sulfur Oxidation ◽  
Co2 Assimilation ◽  
Amino Acid Identity ◽  
Rrna Gene ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Biological Phosphorus

Two metagenome-assembled genomes (MAGs), obtained from laboratory-scale enhanced biological phosphorus removal bioreactors, were analyzed. The values of 16S rRNA gene sequence identity, average nucleotide identity, and average amino acid identity indicated that these genomes, designated as RT and SSD2, represented two novel species within the genus Thiothrix, ‘Candidatus Thiothrix moscowensis’ and ‘Candidatus Thiothrix singaporensis’. A complete set of genes for the tricarboxylic acid cycle and electron transport chain indicates a respiratory type of metabolism. A notable feature of RT and SSD2, as well as other Thiothrix species, is the presence of a flavin adenine dinucleotide (FAD)-dependent malate:quinone oxidoreductase instead of nicotinamide adenine dinucleotide (NAD)-dependent malate dehydrogenase. Both MAGs contained genes for CO2 assimilation through the Calvin–Benson–Bassam cycle; sulfide oxidation (sqr, fccAB), sulfur oxidation (rDsr complex), direct (soeABC) and indirect (aprBA, sat) sulfite oxidation, and the branched Sox pathway (SoxAXBYZ) of thiosulfate oxidation to sulfur and sulfate. All these features indicate a chemoorganoheterotrophic, chemolithoautotrophic, and chemolithoheterotrophic lifestyle. Both MAGs comprise genes for nitrate reductase and NO-reductase, while SSD2 also contains genes for nitrite reductase. The presence of polyphosphate kinase and exopolyphosphatase suggests that RT and SSD2 could accumulate and degrade polyhosphates during the oxic-anoxic growth cycle in the bioreactors, such as typical phosphate-accumulating microorganisms.

scholarly journals Extensive Thioautotrophic Gill Endosymbiont Diversity within a Single Ctena orbiculata (Bivalvia: Lucinidae) Population and Implications for Defining Host-Symbiont Specificity and Species Recognition

mSystems ◽  
2019 ◽  
Vol 4 (4) ◽  
Author(s):  
Shen Jean Lim ◽  
Louie Alexander ◽  
Annette Summers Engel ◽  
Audrey T. Paterson ◽  
Laurie C. Anderson ◽  
...  
Keyword(s):  
Gene Diversity ◽  
Species Recognition ◽  
Bacterial Species ◽  
Sulfide Oxidation ◽  
Taxonomic Diversity ◽  
Amino Acid Identity ◽  
Genetic Differences ◽  
Rrna Gene ◽  
Association Patterns ◽  
Content Type

ABSTRACT Seagrass-dwelling members of the bivalve family Lucinidae harbor environmentally acquired gill endosymbionts. According to previous studies, lucinid symbionts potentially represent multiple strains from a single thioautotrophic gammaproteobacterium species. This study utilized genomic- and transcriptomic-level data to resolve symbiont taxonomic, genetic, and functional diversity from Ctena orbiculata endosymbiont populations inhabiting carbonate-rich sediment at Sugarloaf Key, FL (USA). The sediment had mixed seagrass and calcareous green alga coverage and also was colonized by at least five other lucinid species. Four coexisting, thioautotrophic endosymbiont operational taxonomic units (OTUs), likely representing four strains from two different bacterial species, were identified from C. orbiculata. Three of these OTUs also occurred at high relative abundances in the other sympatric lucinid species. Interspecies genetic differences averaged about 5% lower at both pairwise average nucleotide identity and amino acid identity than interstrain differences. Despite these genetic differences, C. orbiculata endosymbionts shared a high number of metabolic functions, including highly expressed thioautotrophy-related genes and a moderately to weakly expressed conserved one-carbon (C1) oxidation gene cluster previously undescribed in lucinid symbionts. Few symbiont- and host-related genes, including those encoding symbiotic sulfurtransferase, host respiratory functions, and host sulfide oxidation functions, were differentially expressed between seagrass- and alga-covered sediment locations. In contrast to previous studies, the identification of multiple endosymbiont taxa within and across C. orbiculata individuals, which were also shared with other sympatric lucinid species, suggests that neither host nor endosymbiont displays strict taxonomic specificity. This necessitates further investigations into the nature and extent of specificity of lucinid hosts and their symbionts. IMPORTANCE Symbiont diversity and host/symbiont functions have been comprehensively profiled for only a few lucinid species. In this work, unprecedented thioautotrophic gill endosymbiont taxonomic diversity was characterized within a Ctena orbiculata population associated with both seagrass- and alga-covered sediments. Endosymbiont metabolisms included known chemosynthetic functions and an additional conserved, previously uncharacterized C1 oxidation pathway. Lucinid-symbiont associations were not species specific because this C. orbiculata population hosted multiple endosymbiont strains and species, and other sympatric lucinid species shared overlapping symbiont 16S rRNA gene diversity profiles with C. orbiculata. Our results suggest that lucinid-symbiont association patterns within some host species could be more taxonomically diverse than previously thought. As such, this study highlights the importance of holistic analyses, at the population, community, and even ecosystem levels, in understanding host-microbe association patterns.

scholarly journals Aliikangiella coralliicola sp. nov., a bacterium isolated from coral Porites lutea, and proposal of Pleioneaceae fam. nov. to accommodate Pleionea and Aliikangiella

2020 ◽  
Vol 70 (11) ◽  
pp. 5880-5887 ◽  
Author(s):  
Guanghua Wang ◽  
Ge Dang ◽  
Shuailiang Xu ◽  
Jianfeng Liu ◽  
Hongfei Su ◽  
...  
Keyword(s):  
Type Species ◽  
Amino Acid Identity ◽  
Comparative Genomic ◽  
Global Alignment ◽  
Rrna Gene ◽  
Polar Lipid Profile ◽  
Porites Lutea ◽  
Content Type ◽  
Link Type ◽  
Average Amino Acid Identity

A novel Gram-stain-negative, non-endospore-forming, motile, and aerobic bacterial strain, M105T, was isolated from coral Porites lutea, and was subjected to a polyphasic taxonomic study. Global alignment based on 16S rRNA gene sequences indicated that M105T shares the highest sequence identity of 94.5 % with Aliikangiella marina GYP-15T. The average nucleotide identity (ANI) and average amino acid identity (AAI) between M105T and A. marina GYP-15T was 69.8 and 71.6 %, respectively. On the basis of the results of phenotypic, chemotaxonomic, phylogenetic, phylogenomic, and comparative genomic analyses, it is concluded that M105T should represent a novel species in the genus Aliikangiella , for which the name Aliikangiella coralliicola sp. nov. is proposed. The type strain is M105T (=MCCC 1K03773T= KCTC 72442T). Furthermore, the family Kangiellaceae was classified into two families on the basis of phylogenetic, phylogenomic, polar lipid profile and motility variations. The novel family Pleioneaceae fam. nov. is proposed to accommodate the genera Aliikangiella and Pleionea .

scholarly journals Comparative genomics reveals a novel genetic organization of the sad cluster in the sulfonamide-degrader ‘Candidatus Leucobacter sulfamidivorax’ strain GP

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Ana C. Reis ◽  
Boris A. Kolvenbach ◽  
Mohamed Chami ◽  
Luís Gales ◽  
Conceição Egas ◽  
...  
Keyword(s):  
Comparative Genomics ◽  
Draft Genome ◽  
Genomic Analysis ◽  
Amino Acid Identity ◽  
Culture Conditions ◽  
Comparative Genomic ◽  
Rrna Gene ◽  
Functional Studies ◽  
Conserved Genes ◽  
Gene Similarity

Abstract Background Microbial communities recurrently establish metabolic associations resulting in increased fitness and ability to perform complex tasks, such as xenobiotic degradation. In a previous study, we have described a sulfonamide-degrading consortium consisting of a novel low-abundant actinobacterium, named strain GP, and Achromobacter denitrificans PR1. However, we found that strain GP was unable to grow independently and could not be further purified. Results Previous studies suggested that strain GP might represent a new putative species within the Leucobacter genus (16S rRNA gene similarity < 97%). In this study, we found that average nucleotide identity (ANI) with other Leucobacter spp. ranged between 76.8 and 82.1%, further corroborating the affiliation of strain GP to a new provisional species. The average amino acid identity (AAI) and percentage of conserved genes (POCP) values were near the lower edge of the genus delimitation thresholds (65 and 55%, respectively). Phylogenetic analysis of core genes between strain GP and Leucobacter spp. corroborated these findings. Comparative genomic analysis indicates that strain GP may have lost genes related to tetrapyrrole biosynthesis and thiol transporters, both crucial for the correct assembly of cytochromes and aerobic growth. However, supplying exogenous heme and catalase was insufficient to abolish the dependent phenotype. The actinobacterium harbors at least two copies of a novel genetic element containing a sulfonamide monooxygenase (sadA) flanked by a single IS1380 family transposase. Additionally, two homologs of sadB (4-aminophenol monooxygenase) were identified in the metagenome-assembled draft genome of strain GP, but these were not located in the vicinity of sadA nor of mobile or integrative elements. Conclusions Comparative genomics of the genus Leucobacter suggested the absence of some genes encoding for important metabolic traits in strain GP. Nevertheless, although media and culture conditions were tailored to supply its potential metabolic needs, these conditions were insufficient to isolate the PR1-dependent actinobacterium further. This study gives important insights regarding strain GP metabolism; however, gene expression and functional studies are necessary to characterize and further isolate strain GP. Based on our data, we propose to classify strain GP in a provisional new species within the genus Leucobacter, ‘Candidatus Leucobacter sulfamidivorax‘.

scholarly journals Comparative genomic analysis of Flavobacteriaceae: insights into carbohydrate metabolism, gliding motility and secondary metabolite biosynthesis.

2020 ◽  
Author(s):  
Asimenia Gavriilidou ◽  
Johanna Gutleben ◽  
Dennis Versluis ◽  
Francesca Forgiarini ◽  
Mark WJ van Passel ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Carbohydrate Metabolism ◽  
Secondary Metabolite ◽  
Gene Clusters ◽  
Gliding Motility ◽  
Ecological Niches ◽  
Comparative Genomic ◽  
Rrna Gene ◽  
Metabolic Potential ◽  
Secondary Metabolite Biosynthesis

Abstract BackgroundMembers of the bacterial family Flavobacteriaceae are widely distributed in the marine environment and often found associated with algae, fish, detritus or marine invertebrates. Yet, little is known about the characteristics that drive their ubiquity in diverse ecological niches. Here, we provide an overview of functional traits common to taxonomically diverse members of the family Flavobacteriaceae from different environmental sources, with a focus on the Marine clade. We include seven newly sequenced marine sponge-derived strains that were also tested for gliding motility and antimicrobial activity. ResultsComparative genomics revealed that genome similarities appeared to be correlated to 16S rRNA gene phylogeny, while differences were mostly associated with nutrient acquisition, such as carbohydrate metabolism and gliding motility. The high frequency and diversity of genes encoding polymer-degrading enzymes support the capacity of marine Flavobacteriaceae to utilize diverse carbon sources. Homologs of gliding proteins were widespread among all studied Flavobacteriaceae in contrast to members of other phyla, highlighting the particular presence of this feature within the Bacteroidetes. Notably, not all gliding bacteria formed spreading colonies. Genome mining uncovered a diverse secondary metabolite biosynthesis arsenal of Flavobacteriaceae with high prevalence of gene clusters encoding pathways for the production of antimicrobial, antioxidant and cytotoxic compounds. Antimicrobial activity tests showed, however, that the phenotype differed from the genome-derived predictions for the seven tested strains.ConclusionsOur study elucidates the functional repertoire of marine Flavobacteriaceae and highlights the need to combine genomic and experimental data while using the appropriate stimuli to unlock their uncharted metabolic potential.

scholarly journals Pseudodesulfovibrio cashew sp. Nov., a Novel Deep-Sea Sulfate-Reducing Bacterium, Linking Heavy Metal Resistance and Sulfur Cycle

2021 ◽  
Vol 9 (2) ◽  
pp. 429
Author(s):  
Rikuan Zheng ◽  
Shimei Wu ◽  
Chaomin Sun
Keyword(s):  
Heavy Metal ◽  
Sulfate Reduction ◽  
Marine Sediments ◽  
Deep Sea ◽  
Sulfur Cycle ◽  
Metal Sulfides ◽  
Phenotypic Traits ◽  
Dissimilatory Sulfate Reduction ◽  
Metabolic Potential ◽  
Sulfate Reducing

Sulfur cycling is primarily driven by sulfate reduction mediated by sulfate-reducing bacteria (SRB) in marine sediments. The dissimilatory sulfate reduction drives the production of enormous quantities of reduced sulfide and thereby the formation of highly insoluble metal sulfides in marine sediments. Here, a novel sulfate-reducing bacterium designated Pseudodesulfovibrio cashew SRB007 was isolated and purified from the deep-sea cold seep and proposed to represent a novel species in the genus of Pseudodesulfovibrio. A detailed description of the phenotypic traits, phylogenetic status and central metabolisms of strain SRB007 allowed the reconstruction of the metabolic potential and lifestyle of a novel member of deep-sea SRB. Notably, P. cashew SRB007 showed a strong ability to resist and remove different heavy metal ions including Co2+, Ni2+, Cd2+ and Hg2+. The dissimilatory sulfate reduction was demonstrated to contribute to the prominent removal capability of P. cashew SRB007 against different heavy metals via the formation of insoluble metal sulfides.

scholarly journals Biogeochemistry and Community Composition of Iron- and Sulfur-Precipitating Microbial Mats at the Chefren Mud Volcano (Nile Deep Sea Fan, Eastern Mediterranean)

2008 ◽  
Vol 74 (10) ◽  
pp. 3198-3215 ◽  
Author(s):  
Enoma O. Omoregie ◽  
Vincent Mastalerz ◽  
Gert de Lange ◽  
Kristina L. Straub ◽  
Andreas Kappler ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Microbial Mats ◽  
Eastern Mediterranean ◽  
Sulfide Oxidation ◽  
Mud Volcano ◽  
Rrna Gene ◽  
Anaerobic Oxidation Of Methane ◽  
Gene Sequences ◽  
16S Rrna Gene Sequences

ABSTRACT In this study we determined the composition and biogeochemistry of novel, brightly colored, white and orange microbial mats at the surface of a brine seep at the outer rim of the Chefren mud volcano. These mats were interspersed with one another, but their underlying sediment biogeochemistries differed considerably. Microscopy revealed that the white mats were granules composed of elemental S filaments, similar to those produced by the sulfide-oxidizing epsilonproteobacterium “Candidatus Arcobacter sulfidicus.” Fluorescence in situ hybridization indicated that microorganisms targeted by a “Ca. Arcobacter sulfidicus”-specific oligonucleotide probe constituted up to 24% of the total the cells within these mats. Several 16S rRNA gene sequences from organisms closely related to “Ca. Arcobacter sulfidicus” were identified. In contrast, the orange mat consisted mostly of bright orange flakes composed of empty Fe(III) (hydr)oxide-coated microbial sheaths, similar to those produced by the neutrophilic Fe(II)-oxidizing betaproteobacterium Leptothrix ochracea. None of the 16S rRNA gene sequences obtained from these samples were closely related to sequences of known neutrophilic aerobic Fe(II)-oxidizing bacteria. The sediments below both types of mats showed relatively high sulfate reduction rates (300 nmol·cm−3·day−1) partially fueled by the anaerobic oxidation of methane (10 to 20 nmol·cm−3·day−1). Free sulfide produced below the white mat was depleted by sulfide oxidation within the mat itself. Below the orange mat free Fe(II) reached the surface layer and was depleted in part by microbial Fe(II) oxidation. Both mats and the sediments underneath them hosted very diverse microbial communities and contained mineral precipitates, most likely due to differences in fluid flow patterns.

Reclassification of Parvularcula flava as Aquisalinus luteolus nom. nov. and emended description of the genus Aquisalinus

2021 ◽  
Vol 71 (10) ◽  
Author(s):  
Jun-Jie Ying ◽  
Zhi-Cheng Wu ◽  
Yuan-Chun Fang ◽  
Lin Xu ◽  
Cong Sun
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Type Species ◽  
Comparative Genomic ◽  
Rrna Gene ◽  
Gene Sequences ◽  
16S Rrna Gene Sequences ◽  
Content Type ◽  
Link Type ◽  
Type Strains

Parvularcula flava was proposed as a novel member of genus Parvularcula in 2016. Some time earlier, Aquisalinus flavus has been proposed as a novel species of a novel genus named Aquisalinus . When comparing the 16S rRNA gene sequences of type strains P. flava NH6-79T and A. flavus D11M-2T, they showed 97.9 % sequence identity, much higher than the sequence identities 92.7–94.3 % between P. flava NH6-79T and type strains in the genus Parvularcula , indicating that the later proposed novel taxon Parvularcula flava need reclassification. The phylogenetic trees based on 16S rRNA gene sequences and genome sequences both showed that P. flava NH6-79T and A. flavus D11M-2T formed a separated branch away from strains in the genera Parvularcula , Marinicaulis and Amphiplicatus . The average amino acid identity and average nucleotide identity values of P. flava NH6-79T and A. flavus D11M-2T were 87.9 and 85.0 %, respectively, much higher than the values between P. flava NH6-79T and other closely related type strains (54.3 %–58.1 % and 68.6–70.4 %, respectively). P. flava NH6-79T and A. flavus D11M-2T also contained summed feature 8 (C18 : 1  ω6c and/or C18 : 1  ω7c) and C16 : 0 as major fatty acids, distinguishing them from other closely related taxa. Based on the results of the phylogenetic, comparative genomic and phenotypic analyses, Parvularcula flava should be reclassified as Aquisalinus luteolus nom. nov. and the description of genus Aquisalinus is emended.

Muriicola soli sp. nov., isolated from soil

2021 ◽  
Vol 71 (7) ◽  
Author(s):  
Hye Jeong Kang ◽  
Min-Kyeong Kim ◽  
Su Gwon Roh ◽  
Seung Bum Kim
Keyword(s):  
Related Species ◽  
Type Species ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
16S Rrna Gene Sequences ◽  
Content Type ◽  
Link Type ◽  
The Family ◽  
Optimum Ph ◽  
Genomic Characterization

A Gram-stain-negative, oxidase-positive, catalase-positive, aerobic, orange-pigmented, rod-shaped and non-motile bacterium designated strain MMS17-SY002T was isolated from island soil. The isolate grew at 20–37 °C (optimum, 30 °C), at pH 6.0–9.5 (optimum, pH 7) and in the presence of 0.5–4.0 % (w/v) NaCl (optimum, 2.0 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain MMS17-SY002T was mostly related to the genus Muriicola of the family Flavobacteriaceae and had highest sequence similarity of 96.82 % to Muriicola marianensis A6B8T and Muriicola jejuensis EM44T, but formed a distinct phylogenetic line within the genus. Chemotaxonomic analyses showed that menaquinone 6 was the predominant isoprenoid quinone, the major fatty acids were iso-C15 : 1 G and iso-C15 : 0, and the diagnostic polar lipid was phosphatidylethanolamine. The genomic DNA G+C content was 42.4 mol%. Strain MMS17-SY002T could be distinguished from related species by the combination of trypsin, α-chymotrypsin, acid phosphatase, naphthol-AS-BI-phosphohydrolase, α-galactosidase, β-galactosidase and β-glucosidase activities. The orthologous average nucleotide identity between the genomes of strain MMS17-SY002T and M. jejuensis and that between the strain and M. marianensis A6B8T were 73.26 and 73.33%, respectively, thus confirming the separation of the strain from related species at species level. Based on the phenotypic, phylogenetic, chemotaxonomic and genomic characterization, MMS17-SY002T should be recognized as a novel species of the genus Muriicola , for which the name Muriicola soli sp. nov. is proposed. The type strain is MMS17-SY002T (=KCTC 62790T=JCM 32370T).

scholarly journals Thermogenic hydrocarbons fuel a redox stratified subseafloor microbiome in deep sea cold seep sediments

2020 ◽  
Author(s):  
Xiyang Dong ◽  
Jayne E. Rattray ◽  
D. Calvin Campbell ◽  
Jamie Webb ◽  
Anirban Chakraborty ◽  
...  
Keyword(s):  
Deep Sea ◽  
Hydrogen Oxidation ◽  
Sulfide Oxidation ◽  
Cold Seep ◽  
Reductive Dehalogenation ◽  
Cold Seeps ◽  
Community Members ◽  
Metabolic Potential ◽  
Near Surface ◽  
Fumarate Addition

AbstractAt marine cold seeps, gaseous and liquid hydrocarbons migrate from deep subsurface origins to the sediment-water interface. Cold seep sediments are known to host taxonomically diverse microorganisms, but little is known about their metabolic potential and depth distribution in relation to hydrocarbon and electron acceptor availability. In this work, we combined geochemical, metagenomic and metabolomic measurements in distinct sediment redox regimes to profile microbial activities within the uppermost 350 cm of a newly discovered cold seep in the NW Atlantic deep sea (2.3 km water depth). Depth-resolved metagenomic profiling revealed compositional and functional differentiation between near-surface sediments (dominated by Proteobacteria) and deeper subsurface layers (dominated by Atribacteria, Chloroflexi, Euryarchaeota and Lokiarchaeota). Metabolic capabilities of community members were inferred from 376 metagenome-assembled genomes spanning 46 phyla (including five novel candidate phyla). In deeper sulfate-reducing and methanogenic sediments, various community members are capable of anaerobically oxidizing short-chain alkanes (alkyl-CoM reductase pathway), longer-chain alkanes (fumarate addition pathway), and aromatic hydrocarbons (fumarate addition and subsequent benzoyl-CoA pathways). Geochemical profiling demonstrated that hydrocarbon substrates are abundant in this location, thermogenic in origin, and subject to biodegradation. The detection of alkyl-/arylalkylsuccinate metabolites, together with carbon isotopic signatures of ethane, propane and carbon dioxide, support that microorganisms are actively degrading hydrocarbons in these sediments. Hydrocarbon oxidation pathways operate alongside other deep seabed metabolisms such as sulfide oxidation, hydrogen oxidation, carbon fixation, fermentation and reductive dehalogenation. Upward migrated thermogenic hydrocarbons thus sustain diverse microbial communities with activities that affect subseafloor biogeochemical processes across the redox spectrum in deep sea cold seeps.

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