N(ε)-acetyl-β-L-lysine as osmoregulator during salt stress in freshwater anaerobic methane-oxidizing archaea
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ABSTRACT:
PROVIDER: PRJEB70247 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| Aggregatilineales_A4B.fasta.gz | Fasta.gz | |||
| Aggregatilineales_UBA2796.fasta.gz | Fasta.gz | |||
| Bacteria_CLD3_SB21.fasta.gz | Fasta.gz | |||
| Brocadia_1.fasta.gz | Fasta.gz | |||
| Brocadia_2.fasta.gz | Fasta.gz |
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Project description:Maider J. Echeveste Medrano and colleagues characterized the physiological and metabolic response of freshwater methanotrophic archaea to salt stress. The study performed metaproteomics, gene expression profiles and dedicated metabolomics to identify the pathways involved in the salt stress response and the osmolyte present in anaerobic methanotrophic archaea. Correspondence to Cornelia U. Welte c.welte@science.ru.nl
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Project description:NITRIFIERS AND METHANE-OXIDIZING ARCHAEA COEXISTING WITH METHANE AS SOLE CARBON SOURCE
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Project description:Anaerobic oxidation of methane (AOM) is a crucial process limiting the flux of methane from marine environments to the atmosphere. The process is thought to be mediated by three groups of uncultivated methane-oxidizing archaea (ANME-1, 2 and 3). Although the responsible microbes have been intensively studied for more than a decade, central mechanistic details remain unresolved. On the basis of an integrated analysis of both environmental metatranscriptome and single-aggregate genome of a highly active AOM enrichment dominated by ANME-2a, we provide evidence for a complete and functioning AOM pathway in ANME-2a. All genes required for performing the seven steps of methanogenesis from CO2 were found present and actively expressed. Meanwhile, genes for energy conservation and electron transportation including those encoding F420H2 dehydrogenase (Fpo), the cytoplasmic and membrane-associated Coenzyme B-Coenzyme M heterodisulfide (CoB-S-SCoM) reductase (HdrABC, HdrDE), cytochrome C and the Rhodobacter nitrogen fixation (Rnf) complex were identified and expressed, whereas genes encoding for hydrogenases were absent. Thus, ANME-2a is likely performing AOM through a complete reversal of methanogenesis from CO2 reduction without involvement of canonical hydrogenase. ANME-2a is demonstrated to possess versatile electron transfer pathways that would provide the organism with more flexibility in substrate utilization and capacity for rapid adjustment to fluctuating environments. This work lays the foundation for understanding the environmental niche differentiation, physiology and evolution of different ANME subgroups.
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Project description:Climate change-driven sea level rise threatens freshwater ecosystems and elicits salinity stress in microbiomes. Methane emissions in these systems are largely mitigated by methane-oxidizing microorganisms. Here, we characterized the physiological and metabolic response of freshwater methanotrophic archaea to salt stress. In our microcosm experiments, inhibition of methanotrophic archaea started at 1%. However, during gradual increase of salt up to 3% in a reactor over 12 weeks, the culture continued to oxidize methane. Using gene expression profiles and metabolomics, we identified a pathway for salt-stress response that produces the osmolyte of anaerobic methanotrophic archaea: N(ε)-acetyl-β-L-lysine. An extensive phylogenomic analysis on N(ε)-acetyl-β-L-lysine-producing enzymes revealed that they are widespread across both bacteria and archaea, indicating a potential horizontal gene transfer and a link to BORG extrachromosomal elements. Physicochemical analysis of bioreactor biomass further indicated the presence of sialic acids and the consumption of intracellular polyhydroxyalkanoates in anaerobic methanotrophs during salt stress.
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Project description:Marine sediments are important methane reservoirs. Methane efflux from the seabed is significantly restricted by anaerobic methanotrophic (ANME) archaea through a process known as anaerobic oxidation of methane (AOM). Different clades of ANME archaea occupy distinct niches in methane seeps, but their underlying molecular mechanisms still need to be fully understood. To provide genetic explanations for the niche partitioning of ANME archaea, we applied comparative genomic analysis to ANME archaeal genomes retrieved from global methane seeps. Our results showed that ANME-2 archaea are more prevalent than ANME-1 archaea in shallow sediments because they carry genes that encode a significantly higher number of outer membrane multiheme c-type cytochromes and flagellar proteins. These features make ANME-2 archaea perform direct interspecies electron transfer better and benefit more from electron acceptors in AOM. Besides, ANME-2 archaea carry genes that encode extra peroxidase compared to ANME-1 archaea, which may lead to ANME-2 archaea better tolerating oxygen toxicity. In contrast, ANME-1 archaea are more competitive in deep layers than ANME-2 archaea because they carry extra genes (mtb and mtt) for methylotrophic methanogenesis and a significantly higher number of frh and mvh genes for hydrogenotrophic methanogenesis. Additionally, ANME-1 archaea carry exclusive genes (sqr, TST, and mddA) involved in sulfide detoxification compared to ANME-2 archaea, leading to stronger sulfide tolerance. Overall, this study reveals the genomic mechanisms shaping the niche partitioning among ANME archaea in global methane seeps. IMPORTANCE Anaerobic methanotrophic (ANME) archaea are important methanotrophs in marine sediment, controlling the flux of biologically generated methane, which plays an essential role in the marine carbon cycle and climate change. So far, no strain of this lineage has been isolated in pure culture, which makes metagenomics one of the fundamental approaches to reveal their metabolic potential. Although the niche partitioning of ANME archaea was frequently reported in different studies, whether this pattern was consistent in global methane seeps had yet to be verified, and little was known about the genetic mechanisms underlying it. Here, we reviewed and analyzed the community structure of ANME archaea in global methane seeps and indicated that the niche partitioning of ANME archaea was statistically supported. Our comparative genomic analysis indicated that the capabilities of interspecies electron transfer, methanogenesis, and the resistance of oxygen and hydrogen sulfide could be critical in defining the distribution of ANME archaea in methane seep sediment.
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Project description:Borgs are huge extrachromosomal elements (ECE) of anaerobic methane-consuming "Candidatus Methanoperedens" archaea. Here, we used nanopore sequencing to validate published complete genomes curated from short reads and to reconstruct new genomes. 13 complete and four near-complete linear genomes share 40 genes that define a largely syntenous genome backbone. We use these conserved genes to identify new Borgs from peatland soil and to delineate Borg phylogeny, revealing two major clades. Remarkably, Borg genes encoding nanowire-like electron-transferring cytochromes and cell surface proteins are more highly expressed than those of host Methanoperedens, indicating that Borgs augment the Methanoperedens activity in situ. We reconstructed the first complete 4.00 Mbp genome for a Methanoperedens that is inferred to be a Borg host and predicted its methylation motifs, which differ from pervasive TC and CC methylation motifs of the Borgs. Thus, methylation may enable Methanoperedens to distinguish their genomes from those of Borgs. Very high Borg to Methanoperedens ratios and structural predictions suggest that Borgs may be capable of encapsulation. The findings clearly define Borgs as a distinct class of ECE with shared genomic signatures, establish their diversification from a common ancestor with genetic inheritance, and raise the possibility of periodic existence outside of host cells.
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Project description:Anaerobic methane oxidizing archaea (ANME) mediate anaerobic oxidation of methane (AOM) in marine sediments and are therefore important for controlling atmospheric methane concentrations in the water column and ultimately the atmosphere. Numerous previous studies have revealed that AOM is coupled to the reduction of different electron acceptors such as sulfate, nitrate/nitrite or Fe(III)/Mn(IV). However, the influence of electron acceptor availability on the in situ ANME community composition in sediments remains largely unknown. Here, we investigated the electron acceptor availability and compared the microbial in situ communities of three methane-rich locations offshore the sub-Antarctic island South Georgia, by Illumina sequencing and qPCR of mcrA genes. The methanic zone (MZ) sediments of Royal Trough and Church Trough comprised high sulfide concentrations of up to 4 and 19 mM, respectively. In contrast, those of the Cumberland Bay fjord accounted for relatively high concentrations of dissolved iron (up to 186 μM). Whereas the ANME community in the sulfidic sites Church Trough and Royal Trough mainly comprised members of the ANME-1 clade, the order-level clade "ANME-1-related" (Lever and Teske, 2015) was most abundant in the iron-rich site in Cumberland Bay fjord, indicating that the availability of electron acceptors has a strong selective effect on the ANME community. This study shows that potential electron acceptors for methane oxidation may serve as environmental filters to select for the ANME community composition and adds to a better understanding of the global importance of AOM.
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Project description:Recent single-gene-based surveys of deep continental aquifers demonstrated the widespread occurrence of archaea related to Candidatus Methanoperedens nitroreducens (ANME-2d) known to mediate anaerobic oxidation of methane (AOM). However, it is unclear whether ANME-2d mediates AOM in the deep continental biosphere. In this study, we found the dominance of ANME-2d in groundwater enriched in sulfate and methane from a 300-m deep underground borehole in granitic rock. A near-complete genome of one representative species of the ANME-2d obtained from the underground borehole has most of functional genes required for AOM and assimilatory sulfate reduction. The genome of the subsurface ANME-2d is different from those of other members of ANME-2d by lacking functional genes encoding nitrate and nitrite reductases and multiheme cytochromes. In addition, the subsurface ANME-2d genome contains a membrane-bound NiFe hydrogenase gene putatively involved in respiratory H2 oxidation, which is different from those of other methanotrophic archaea. Short-term incubation of microbial cells collected from the granitic groundwater with 13C-labeled methane also demonstrates that AOM is linked to microbial sulfate reduction. Given the prominence of granitic continental crust and sulfate and methane in terrestrial subsurface fluids, we conclude that AOM may be widespread in the deep continental biosphere.
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Project description:The oxidation of methane in anoxic marine sediments is thought to be mediated by a consortium of methane-consuming archaea and sulfate-reducing bacteria. In this study, we compared results of rRNA gene (rDNA) surveys and lipid analyses of archaea and bacteria associated with methane seep sediments from several different sites on the Californian continental margin. Two distinct archaeal lineages (ANME-1 and ANME-2), peripherally related to the order Methanosarcinales, were consistently associated with methane seep marine sediments. The same sediments contained abundant (13)C-depleted archaeal lipids, indicating that one or both of these archaeal groups are members of anaerobic methane-oxidizing consortia. (13)C-depleted lipids and the signature 16S rDNAs for these archaeal groups were absent in nearby control sediments. Concurrent surveys of bacterial rDNAs revealed a predominance of delta-proteobacteria, in particular, close relatives of Desulfosarcina variabilis. Biomarker analyses of the same sediments showed bacterial fatty acids with strong (13)C depletion that are likely products of these sulfate-reducing bacteria. Consistent with these observations, whole-cell fluorescent in situ hybridization revealed aggregations of ANME-2 archaea and sulfate-reducing Desulfosarcina and Desulfococcus species. Additionally, the presence of abundant (13)C-depleted ether lipids, presumed to be of bacterial origin but unrelated to ether lipids of members of the order Desulfosarcinales, suggests the participation of additional bacterial groups in the methane-oxidizing process. Although the Desulfosarcinales and ANME-2 consortia appear to participate in the anaerobic oxidation of methane in marine sediments, our data suggest that other bacteria and archaea are also involved in methane oxidation in these environments.
| S-EPMC92814 | biostudies-literature
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