Biomarker Response of Aerobic Methanotrophs to Methane Oxidation Rates and Short-Term Methane and Oxygen Limitation
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PROVIDER: PRJNA780482 | ENA |
REPOSITORIES: ENA
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Project description:Methanotrophs, which help regulate atmospheric levels of methane, are active in diverse natural and man-made environments. This range of habitats and the feast-famine cycles seen by many environmental methanotrophs suggest that methanotrophs dynamically mediate rates of methane oxidation. Global methane budgets require ways to account for this variability in time and space. Functional gene biomarker transcripts are increasingly being studied to inform the dynamics of diverse biogeochemical cycles. Previously, per-cell transcript levels of the methane oxidation biomarker, pmoA, were found to vary quantitatively with respect to methane oxidation rates in model aerobic methanotroph, Methylosinus trichosporium OB3b. In the present study, these trends were explored for two additional aerobic methanotroph pure cultures, Methylocystis parvus OBBP and Methylomicrobium album BG8. At steady-state conditions, per cell pmoA mRNA transcript levels strongly correlated with per cell methane oxidation across the three methanotrophs across many orders of magnitude of activity (R2 = 0.91). Additionally, genome-wide expression data (RNA-seq) were used to explore transcriptomic responses of steady state M. album BG8 cultures to short-term CH4 and O2 limitation. These limitations induced regulation of genes involved in central carbon metabolism (including carbon storage), cell motility, and stress response.
2021-11-17 | GSE188821 | GEO
Project description: Not available
| S-EPMC8406961 | biostudies-literature
Project description:Connecting genes to phenotypic traits in bacteria is often challenging because of a lack of environmental cues in laboratory settings. However, laboratory-based model ecosystems offer a means to better account for natural conditions compared to standard planktonic cultures, aiding in the linking of genotypes and phenotypes. Here, we present a simple, cost-effective, laboratory-based model ecosystem to study aerobic methane-oxidizing bacteria (methanotrophs). This system, referred to as the gradient syringe, is made by inoculating bacteria into semi-solid agarose held within a disposable syringe. Empty space at one end of the syringe is flushed with methane gas, while the other end is open to the atmosphere through a sterile filter. We show this system replicates the methane-oxygen counter gradient typically found in the natural soil environment of methanotrophs. Culturing the methanotroph Methylomonas sp. strain LW13 in this system produced a distinct horizontal band at the intersection of the counter gradient, which we discovered was due not to increased cell growth at this location but instead to an increased amount of extracellular polymeric substances (EPS). We also discovered that different methanotrophic taxa formed EPS bands with distinct locations and morphologies when grown in the methane-oxygen counter gradient. By comparing transcriptomic data from LW13 growing within and surrounding this EPS band, we identified genes implicated in cell growth and EPS formation within the gradient syringe, and validated the involvement of these genes with knockout strains. This work highlights the use of a laboratory-based model ecosystem that more closely mimics the natural environment to uncover methanotroph phenotypes missing from standard planktonic cultures, and link these phenotypes their genetic determinants.
2023-10-05 | GSE243827 | GEO
Project description:The bacteria that grow on methane aerobically (methanotrophs) support populations of non-methanotrophs in the natural environment by excreting methane-derived carbon. One group of excreted compounds are short-chain organic acids, generated in highest abundance when cultures are grown under O2-starvation. We examined this O2-starvation condition in the methanotroph Methylomicrobium buryatense 5GB1C . Under prolonged O2-starvation in a closed vial, this methanotroph increases the amount of acetate excreted about 10-fold, but the formate, lactate, and succinate excreted do not respond to this culture condition. In bioreactor cultures, the amount of each excreted product is similar across a range of growth rates and limiting substrates, including O2-limitation. A set of mutants were generated in genes predicted to be involved in generating or regulating excretion of these compounds and tested for growth defects, and changes in excretion products. The phenotypes and associated metabolic flux modeling suggested that in M. buryatense 5GB1C, formate and acetate are excreted in response to redox imbalance, and the resulting metabolic state represents a combination of fermentation and respiration metabolism.
2017-08-24 | GSE101981 | GEO
Project description:RNA-Seq profiling of Methylomicrobium alcaliphilum strain 20Z grown in batch on methane. The RNA-Seq work is one part of a systems approach to characterizing metabolism of 20Z during growth on methane. We demonstrate that methane assimilation is coupled with a highly efficient pyrophosphate-mediated glycolytic pathway, which under O2 limitation participates in a novel form of fermentation-based methanotrophy. This surprising discovery suggests a novel mode of methane utilization in oxygen-limited environments, and opens new opportunities for a modular approach towards producing a variety of excreted chemical products using methane as a feedstock. Four replicates of batch growth
2013-09-25 | E-GEOD-51145 | biostudies-arrayexpress
Project description:Unexpected role of canonical aerobic methanotrophs in upland agricultural soils
| PRJEB27460 | ENA
Project description:RNA-Seq profiling of Methylomicrobium alcaliphilum strain 20Z grown in batch on methane. The RNA-Seq work is one part of a systems approach to characterizing metabolism of 20Z during growth on methane. We demonstrate that methane assimilation is coupled with a highly efficient pyrophosphate-mediated glycolytic pathway, which under O2 limitation participates in a novel form of fermentation-based methanotrophy. This surprising discovery suggests a novel mode of methane utilization in oxygen-limited environments, and opens new opportunities for a modular approach towards producing a variety of excreted chemical products using methane as a feedstock.
2013-09-25 | GSE51145 | GEO
Project description:Methane oxidation by aerobic methanotrophs is well-known to be strongly regulated by the availability of copper, i.e., the “copper-switch”. That is, there are two forms of the methane monooxygenase: a cytoplasmic or soluble methane monooxygenase (sMMO) and a membrane-bound or particulate methane monooxygenase (pMMO). sMMO is only expressed and active in the absence of copper, while pMMO requires copper. Previous work has also shown that one gene in the operon of the soluble methane monooxygenase – mmoD – also plays a critical role, but its function is still vague. Herein we show that MmoD is not needed for expression of genes in the sMMO gene cluster but is critical for formation of sMMO polypeptides and sMMO activity in Methylosinus trichosporium OB3b, indicating that MmoD plays a key post-transcriptional role in maturation of sMMO. Further, data also show that MmoD controls expression of methanobactin, a unique copper-binding compound used by some methanotrophs for copper collection. Collectively these results provide greater insights into the components of the “copper-switch” and thus provide new strategies to manipulate methanotrophic activity.
2023-09-29 | PXD045741 | Pride
Project description:Metabolic flexibility in aerobic methane oxidising bacteria (methanotrophs) enhances cell growth and survival in instances where resources are variable or limiting. Examples include the production of intracellular compounds (such as glycogen or polyhydroxyalkanoates) in response to unbalanced growth conditions and the use of some energy substrates, besides methane, when available. Indeed, recent studies show that verrucomicrobial methanotrophs can grow mixotrophically through oxidation of hydrogen and methane gases via respiratory membrane-bound group 1d [NiFe] hydrogenases and methane monooxygenases respectively. Hydrogen metabolism is particularly important for adaptation to methane and oxygen limitation, suggesting this metabolic flexibility may confer growth and survival advantages. In this work, we provide evidence that, in adopting a mixotrophic growth strategy, the thermoacidophilic methanotroph, Methylacidiphilum sp. RTK17.1 changes its growth rate, biomass yields and the production of intracellular glycogen reservoirs. Under nitrogen-fixing conditions, removal of hydrogen from the feed-gas resulted in a 14 % reduction in observed growth rates and a 144% increase in cellular glycogen content. Concomitant with increases in glycogen content, the total protein content of biomass decreased following the removal of hydrogen. Transcriptome analysis of Methylacidiphilum sp. RTK17.1 revealed a 3.5-fold upregulation of the Group 1d [NiFe] hydrogenase in response to oxygen limitation and a 4-fold upregulation of nitrogenase encoding genes (nifHDKENX) in response to nitrogen limitation. Genes associated with glycogen synthesis and degradation were expressed constitutively and did not display evidence of transcriptional regulation. Collectively these data further challenge the belief that hydrogen metabolism in methanotrophic bacteria is primarily associated with energy conservation during nitrogen fixation and suggests its utilisation provides a competitive growth advantage within hypoxic habitats.
2019-10-01 | GSE132517 | GEO
Project description:Aerobic methanotrophic bacteria can use methane as their sole energy source. The discovery of ‘Ca. Methylacidiphilum fumariolicum’ strain SolV and other verrucomicrobial methanotrophs has revealed that the ability of bacteria to oxidize CH4 is much more diverse than has previously been assumed in terms of ecology, phylogeny and physiology. A remarkable characteristic of the methane-oxidizing Verrucomicrobia is their extremely acidophilic phenotype, growing even below pH 1. In this study we used RNA-Seq to analyze the metabolic regulation of ‘Ca. M. fumariolicum’ SolV cells growing at μmax in batch culture or under nitrogen fixing or oxygen limited conditions in chemostats, all at pH 2. The analysis showed that two of the three pmoCAB operons each encoding particulate methane monoxygenases were differentially expressed, probably regulated by the available oxygen. The hydrogen produced during N2 fixation is apparently recycled as demonstrated by the upregulation of the genes encoding a Ni/Fe-dependent hydrogenase. These hydrogenase genes were also upregulated under low oxygen conditions. Handling of nitrosative stress was shown by the expression of the nitric oxide reductase encoding genes norB and norC under all conditions tested, the upregulation of nitrite reductase nirK under oxygen limitation and of hydroxylamine oxidoreductase hao in the presence of ammonium. Unraveling the gene regulation of carbon and nitrogen metabolism helps to understand the underlying physiological adaptations of strain SolV in view of the harsh conditions of its natural ecosystem. Cells grown under 3 different conditions were harvested by centrifugation and 3.1 mg dry weight cells were used for isolation of mRNA, and subsequent synthesis of cDNA (328 ng). The cDNA was used for Illumina sequencing on a Illumina Genome.Analyser II
2012-09-01 | E-GEOD-40528 | biostudies-arrayexpress