Project description:Enrichments with labeled CH4 and NO2 were conducted to test microbial community correlations and constrain potential metabolic interactions between methanotrophs and other one-carbon utilizing microorganisms under low O2 conditions
Project description:The objective of this study was to assess whether Methylocystis sp. strain SC2, as a representative for Methylocystis spp., can utilize hydrogen to optimize the biomass yield by mixed utilization of CH4 and H2, rather than CH4 as the sole source of energy. Thus, we aimed to show that, in the presence of H2, CH4 will primarily be used for synthesis of cell carbon and increased biomass/protein yield. In particular, we intended to explore those CH4/O2 ratios, which maximize the effect of hydrogen addition on the biomass yield and proteome reconstruction of strain SC2. To achieve our goals, we combined hydrogen-based growth experiments with our recently optimized proteomics workflow.
2020-06-03 | PXD015700 | Pride
Project description:Low O2 levels enhance CH4-derived carbon flow into microbial communities in landfill cover soils CH4 derived C flow into landfill microbial communitites
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.
Project description:Background: Biological conversion of the surplus of renewable electricity to CH4 could support energy storage and strengthen the power grid. Biological methanation (BM) is closely linked to the activity of biogas-producing bacterial community and methanogenic Archaea in particular. During reactor operations, the microbiome is often subject to various changes whereby the microorganisms are challenged to adapt to the new conditions. In this study, a hydrogenotrophic-adapted microbial community in a laboratory-scale BM fermenter was monitored for its pH, gas production, conversion yields and composition. To investigate the robustness of BM regarding power oscillations, the biogas microbiome was exposed to five H2 starvations patterns for several hours.
Project description:Characterization of microbial communities at the genomic, transcriptomic, proteomic and metabolomic levels, with a special interest on lipid accumulating bacterial populations, which are naturally enriched in biological wastewater treatment systems and may be harnessed for the conversion of mixed lipid substrates (wastewater) into biodiesel. The project aims to elucidate the genetic blueprints and the functional relevance of specific populations within the community. It focuses on within-population genetic and functional heterogeneity, trying to understand how fine-scale variations contribute to differing lipid accumulating phenotypes. Insights from this project will contribute to the understanding the functioning of microbial ecosystems, and improve optimization and modeling strategies for current and future biological wastewater treatment processes. This project contains datasets derived from the same biological wastewater treatment plant. The data includes metagenomes, metatranscriptomes, metaproteomes and organisms isolated in pure cultures. Characterization of microbial communities at the genomic, transcriptomic, proteomic and metabolomic levels, with a special interest on lipid accumulating bacterial populations, which are naturally enriched in biological wastewater treatment systems and may be harnessed for the conversion of mixed lipid substrates (wastewater) into biodiesel. The project aims to elucidate the genetic blueprints and the functional relevance of specific populations within the community. It focuses on within-population genetic and functional heterogeneity, trying to understand how fine-scale variations contribute to differing lipid accumulating phenotypes. Insights from this project will contribute to the understanding the functioning of microbial ecosystems, and improve optimization and modeling strategies for current and future biological wastewater treatment processes. This project contains datasets derived from the same biological wastewater treatment plant. The data includes metagenomes, metatranscriptomes, metaproteomes and organisms isolated in pure cultures.
Project description:In this study we investigated the steady-state growth of Methylotuvimicrobium alcaliphilum 20ZR in media containing calcium (Ca) or lanthanum (La, a REE element). RNA-seq profiling of Methylomicrobium alcaliphilum strain 20ZR in bioreactor on methane. Sample cultures, La-optimum, La-CH4 limited, Ca-optimum and Ca-CH4 limited, were collected and immediately transferred into tubes containing 5 ml of the stop solution (5% water-equilibrated phenol in ethanol). It was found, that cells supplemented with La show a higher growth rate compared to Ca-cultures; however, the efficiency of carbon conversion, estimated as biomass yield, is higher in cells grown with Ca. The study was financially supported by DOE under FOA DE-FOA-0001085 and by NSF-CBET award 1605031
Project description:In this study, we investigated the metabolic potential of N. marina based on its complete genome sequence and performed physiological experiments to test genome-derived hypotheses. Our data confirm that N. marina benefits from additions of undefined organic carbon substrates, has adaptations to resist oxidative, osmotic and UV light-induced stress and low dissolved pCO2. Additionally, N. marina is able to grow chemoorganotrophically on formate, and is thus not an obligate chemolithoautotroph. We further investigated the metabolic response of N. marina to low (5.6 µM) O2 concentrations. In response to O2-limited conditions, the abundance of a potentially more efficient CO2-fixing pyruvate:ferredoxin oxidoreductase (POR) complex and a high-affinity cbb3-type terminal oxidase increased, suggesting a role in sustaining nitrite oxidation-driven autotrophy under O2 limitation.
Project description:High NH4+ load is known to competitively inhibit bacterial methane oxidation. This is due to a competition between CH4 and NH4+/NH3 for the active site of particulate methane monooxygenase (pMMO), which converts CH4 to CH3OH. Here, we combined growth experiments with global proteomics to elucidate the capability of the methanotroph Methylocystis sp. strain SC2 in acclimatizing to increased NH4+ levels. Our experimental approach also involved amino acid profiling and measurement of NOx compounds. Relative to 1 mM NH4+, high (50 mM and 75 mM) NH4+ load under CH4 replete conditions significantly increased lag phase duration required for proteome adjustment. The proteomic and metabolic responses to increasing ionic and osmotic stress involved significant upregulation of stress-responsive proteins, K+ “salt in” strategy, synthesis of compatible solutes (glutamate and proline), and induction of the glutathione metabolism pathway. A significant increase in the apparent Km value for CH4 oxidation during the growth phase was indicative of increased pMMO-based oxidation of NH4+/NH3 to toxic hydroxylamine. The detoxifying activity of hydroxlyamine oxidoreductase (HAO) led to a significant accumulation of NO2- and, upon decreasing O2 tension, N2O. Putative free intermediate of HAO activity was NO, with NO reductase and hybrid cluster proteins (Hcps) being the candidate enzymes for the reduction of NO to N2O. In summary, strain SC2 has the capacity to precisely rebalance enzymes and osmolyte composition, but the need to simultaneously combat both ionic-osmotic stress and the toxic effects of hydroxylamine may be the reason why its acclimatization capacity is limited to 75 mM NH4+.
Project description:Multispecies biofilms are the predominant form of bacterial growth in natural and human-associated environments. Although the pathways involved in monospecies biofilm have been well characterized, less is known about the metabolic pathways and emergent traits of a multispecies biofilm community. Here, we performed a transcriptome survey of the developmental stages of a 3-species biofilm community and combined it with quantitative imaging and growth experiments. We report the remodelling of central metabolism of two of the three species in this community. Specifically, we observed an increase in the expression of genes associated with glycolysis and pentose phosphate pathways in K. pneumoniae. Similarly, a decrease in the expression of the same pathways in P. protegens was observed along with an increase in expression of glyoxalate cycle genes when grown as a mixed species biofilm, suggesting reorganisation of metabolic pathways and metabolite sharing for the community biofilms. To test the possibility of cross-feeding for the community, planktonic growth experiments revealed that both the Pseudomonads grew well in TCA cycle intermediates, while K. pneumoniae grew poorly when given those carbon sources. Despite this poor growth in mono-culture, K. pneumoniae was still the dominant species in mixed species biofilms cultivated in TCA intermediates as the sole source of carbon. The biofilm growth data, combined with the transcriptomics data, suggests there is reorganisation of metabolism for the community members and may allow for cross-feeding that allows K. pneumoniae to dominate the community. We also demonstrated that sdsA1 of P. aeruginosa was induced upon exposure to the surfactant SDS and that this gene was essential in protecting mono and mixed species biofilms from surfactant stress. This also suggests that the community members can share defence mechanisms. Overall, this study describes a comprehensive transcriptomics level investigation of shared resources, metabolites and stress defence that may underpin the emergent properties of mixed species biofilm communities.