Uncultured methanogenic archaeon
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Project description:uncultured methanogenic archaeon overview
| PRJNA851135 | ENA
Project description:Biogenic methane formation, methanogenesis, a key process in the global carbon cycle is the only energy metabolism known to sustain growth of the microorganisms employing it, the methanogenic archaea. All known methanogenic pathways converge at the methane-liberating step where also the terminal electron acceptor of methanogenic respiration, the heterodisulfide of coenzyme M and coenzyme B is formed. Carbon monoxide (CO) utilization of Methanosarcina acetivorans is unique in that the organism can shift from methanogenesis towards acetogenesis. Here, we show that M. acetivorans can dispense of methanogenesis for energy conservation completely. By disrupting the methanogenic pathway through targeted mutagenesis, followed by adaptive evolution, a strain capable of sustained growth by CO-dependent acetogenesis was created. Still, a minute flux through the methane-liberating reaction remained essential, which was attributed to the involvement of the heterodisulfide in at least one essential anabolic reaction. Genomic and proteomic analysis showed that substantial metabolic rewiring had occurred in the strain. Most notably, heterodisulfide reductase, the terminal respiratory oxidoreductase was eliminated to funnel the heterodisulfide towards anabolism. These results suggest that the metabolic flexibility of “methanogenic” archaea is much greater than anticipated and open avenues for probing the mechanism of energetic coupling and the crosstalk between catabolism and anabolism.
2021-10-05 | PXD022016 | Pride
Project description:Soil transplant serves as a proxy to simulate climate change in realistic climate regimes. Here, we assessed the effects of climate warming and cooling on soil microbial communities, which are key drivers in Earth’s biogeochemical cycles, four years after soil transplant over large transects from northern (N site) to central (NC site) and southern China (NS site) and vice versa. Four years after soil transplant, soil nitrogen components, microbial biomass, community phylogenetic and functional structures were altered. Microbial functional diversity, measured by a metagenomic tool named GeoChip, and phylogenetic diversity are increased with temperature, while microbial biomass were similar or decreased. Nevertheless, the effects of climate change was overridden by maize cropping, underscoring the need to disentangle them in research. Mantel tests and canonical correspondence analysis (CCA) demonstrated that vegetation, climatic factors (e.g., temperature and precipitation), soil nitrogen components and CO2 efflux were significantly correlated to the microbial community composition. Further investigation unveiled strong correlations between carbon cycling genes and CO2 efflux in bare soil but not cropped soil, and between nitrogen cycling genes and nitrification, which provides mechanistic understanding of these microbe-mediated processes and empowers an interesting possibility of incorporating bacterial gene abundance in greenhouse gas emission modeling.
2013-10-30 | GSE51592 | GEO
Project description:Previous studies have identified intervening sequences that encode homing endonucleases within the genes encoding several archaeal DNA polymerases. We report the sequence of the gene encoding the DNA polymerase of Methanococcus voltae and describe evidence that it lacks analogous intervening sequences.
| S-EPMC196983 | biostudies-other
Project description:Tibet is one of the most threatened regions by climate warming, thus understanding how its microbial communities function may be of high importance for predicting microbial responses to climate changes. Here, we report a study to profile soil microbial structural genes, which infers functional roles of microbial communities, along four sites/elevations of a Tibetan mountainous grassland, aiming to explore potential microbial responses to climate changes via a strategy of space-for-time substitution. Using a microarray-based metagenomics tool named GeoChip 4.0, we showed that microbial communities were distinct for most but not all of the sites. Substantial variations were apparent in stress, N and C cycling genes, but they were in line with the functional roles of these genes. Cold shock genes were more abundant at higher elevations. Also, gdh converting ammonium into urea was more abundant at higher elevations while ureC converting urea into ammonium was less abundant, which was consistent with soil ammonium contents. Significant correlations were observed between N-cycling genes (ureC, gdh and amoA) and nitrous oxide flux, suggesting that they contributed to community metabolism. Lastly, we found by CCA, Mantel tests and the similarity tests that soil pH, temperature, NH4+–N and vegetation diversity accounted for the majority (81.4%) of microbial community variations, suggesting that these four attributes were major factors affecting soil microbial communities. Based on these observations, we predict that climate changes in the Tibetan grasslands are very likely to change soil microbial community functional structure, with particular impacts on microbial N cycling genes and consequently microbe-mediated soil N dynamics.
2013-07-13 | GSE48820 | GEO
Project description:Four stable and robust TCE-dechlorinating microbial communities were enriched from TCE-contaminated groundwater under four different conditions exploring two parameters, high and low methanogenic activity (Meth and NoMeth), with and without vitamin B12 supplement (MethB12 and NoMethB12, Meth and NoMeth, respectively). Identical amounts of lactate (2.7 mmol) and TCE (20 μl) were supplied as electron donor and electron acceptor. All four cultures were capable of reductively dechlorinating TCE to VC and ethene. Genomic DNA of the four enrichments was applied on a quad-Dhc-genome microarray in order to characterize the gene content of Dehalococcoides species present in the four enrichments
2013-06-30 | GSE33530 | GEO
Project description:Background: The soil environment is responsible for sustaining most terrestrial plant life on earth, yet we know surprisingly little about the important functions carried out by diverse microbial communities in soil. Soil microbes that inhabit the channels of decaying root systems, the detritusphere, are likely to be essential for plant growth and health, as these channels are the preferred locations of new root growth. Understanding the microbial metagenome of the detritusphere and how it responds to agricultural management such as crop rotations and soil tillage will be vital for improving global food production. Methods: The rhizosphere soils of wheat and chickpea growing under + and - decaying root were collected for metagenomics sequencing. A gene catalogue was established by de novo assembling metagenomic sequencing. Genes abundance was compared between bulk soil and rhizosphere soils under different treatments. Conclusions: The study describes the diversity and functional capacity of a high-quality soil microbial metagenome. The results demonstrate the contribution of the microbiome from decaying root in determining the metagenome of developing root systems, which is fundamental to plant growth, since roots preferentially inhabit previous root channels. Modifications in root microbial function through soil management, can ultimately govern plant health, productivity and food security.
2020-03-06 | GSE146427 | GEO
Project description:Nitrogen fixation occurs in two domains, Archaea and Bacteria. We have characterized a nif (nitrogen fixation) gene cluster in the methanogenic archaeon Methanococcus maripaludis. Sequence analysis revealed eight genes, six with sequence similarity to known nif genes and two with sequence similarity to glnB. The gene order, nifH, ORF105 (similar to glnB), ORF121 (similar to glnB), nifD, nifK, nifE, nifN, and nifX, was the same as that found in part in other diazotrophic methanogens and except for the presence of the glnB-like genes, also resembled the order found in many members of the Bacteria. Using transposon insertion mutagenesis, we determined that an 8-kb region required for nitrogen fixation corresponded to the nif gene cluster. Northern analysis revealed the presence of either a single 7.6-kb nif mRNA transcript or 10 smaller mRNA species containing portions of the large transcript. Polar effects of transposon insertions demonstrated that all of these mRNAs arose from a single promoter region, where transcription initiated 80 bp 5' to nifH. Distinctive features of the nif gene cluster include the presence of the six primary nif genes in a single operon, the placement of the two glnB-like genes within the cluster, the apparent physical separation of the cluster from any other nif genes that might be in the genome, the fragmentation pattern of the mRNA, and the regulation of expression by a repression mechanism described previously. Our study and others with methanogenic archaea reporting multiple mRNAs arising from gene clusters with only a single putative promoter sequence suggest that mRNA processing following transcription may be a common occurrence in methanogens.
| S-EPMC107051 | biostudies-literature
Project description:Although Cas9-mediated genome editing has proven to be a powerful genetic tool in eukaryotes, its application in Bacteria has been limited because of inefficient targeting or repair; and its application to Archaea has yet to be reported. Here we describe the development of a Cas9-mediated genome-editing tool that allows facile genetic manipulation of the slow-growing methanogenic archaeon Methanosarcina acetivorans Introduction of both insertions and deletions by homology-directed repair was remarkably efficient and precise, occurring at a frequency of approximately 20% relative to the transformation efficiency, with the desired mutation being found in essentially all transformants examined. Off-target activity was not observed. We also observed that multiple single-guide RNAs could be expressed in the same transcript, reducing the size of mutagenic plasmids and simultaneously simplifying their design. Cas9-mediated genome editing reduces the time needed to construct mutants by more than half (3 vs. 8 wk) and allows simultaneous construction of double mutants with high efficiency, exponentially decreasing the time needed for complex strain constructions. Furthermore, coexpression the nonhomologous end-joining (NHEJ) machinery from the closely related archaeon, Methanocella paludicola, allowed efficient Cas9-mediated genome editing without the need for a repair template. The NHEJ-dependent mutations included deletions ranging from 75 to 2.7 kb in length, most of which appear to have occurred at regions of naturally occurring microhomology. The combination of homology-directed repair-dependent and NHEJ-dependent genome-editing tools comprises a powerful genetic system that enables facile insertion and deletion of genes, rational modification of gene expression, and testing of gene essentiality.
| S-EPMC5358397 | biostudies-literature
Project description:Acyl homoserine lactone (AHL)-based quorum sensing commonly refers to cell density-dependent regulatory mechanisms found in bacteria. However, beyond bacteria, this cell-to-cell communication mechanism is poorly understood. Here we show that a methanogenic archaeon, Methanosaeta harundinacea 6Ac, encodes an active quorum sensing system that is used to regulate cell assembly and carbon metabolic flux. The methanogen 6Ac showed a cell density-dependent physiology transition, which was related to the AHL present in the spent culture and the filI gene-encoded AHL synthase. Through extensive chemical analyses, a new class of carboxylated AHLs synthesized by FilI protein was identified. These carboxylated AHLs facilitated the transition from a short cell to filamentous growth, with an altered carbon metabolic flux that favoured the conversion of acetate to methane and a reduced yield in cellular biomass. The transcriptomes of the filaments and the short cell forms differed with gene expression profiles consistent with the physiology. In the filaments, genes encoding the initial enzymes in the methanogenesis pathway were upregulated, whereas those for cellular carbon assimilation were downregulated. A luxI-luxR ortholog filI-filR was present in the genome of strain 6Ac. The carboxylated AHLs were also detected in other methanogen cultures and putative filI orthologs were identified in other methanogenic genomes as well. This discovery of AHL-based quorum sensing systems in methanogenic archaea implies that quorum sensing mechanisms are universal among prokaryotes.
| S-EPMC3379639 | biostudies-literature