Project description:This project aims to investigate the metabolic pathways expressed by the active microbial community occurring at the deep continental subsurface. Subsurface chemoLithoautotrophic Microbial Ecosystems (SLiMEs) under oligotrophic conditions are supported by H2; however, the overall ecological trophic structures of these communities are poorly understood. Some deep, fluid-filled fractures in the Witwatersrand Basin, South Africa appear to support inverted trophic pyramids wherein methanogens contributing <5% of the total DNA apparently produce CH4 that supports the rest of the community. Here we show the active metabolic relationships of one such trophic structure by combining metatranscriptomic assemblies, metaproteomic and stable isotopic data, and thermodynamic modeling. Four autotrophic β-proteobacteria genera that are capable of oxidizing sulfur by denitrification dominate. They co-occur with sulfate reducers, anaerobic methane oxidizers and methanogens, which each comprises <5% of the total community. Defining trophic levels of microbial chemolithoautotrophs by the number of transfers from the initial abiotic H2-driven CO2 fixation, we propose a top-down cascade influence of the metabolic consumers that enhances the fitness of the metabolic producers to explain the inverted biomass pyramid of a multitrophic SLiME. Symbiotic partnerships are pivotal in the deep biosphere on and potentially beyond the Earth.
Project description:Deciphering the in situ activities of microorganisms is essential for understanding the biogeochemical processes occurring in complex environments. Here we used environmental metaproteomics to obtain information about the identity and activity of subsurface microbial populations in coal-tar-contaminated groundwater. The present study reports metaproteomic data showing high representation of Candidatus Methylomirabilis oxyfera in our study site’s subsurface microbial community. In addition, eight of the nine proteins of the n-damo pathway were identified—indicating that n-damo is an active process occurring in situ in this habitat.
Project description:Deciphering the in situ activities of microorganisms is essential for understanding the biogeochemical processes occurring in complex environments. Here we used environmental metaproteomics to obtain information about the identity and activity of subsurface microbial populations in coal-tar-contaminated groundwater. The present study reports metaproteomic data showing high representation of Candidatus Methylomirabilis oxyfera in our study site’s subsurface microbial community. In addition, eight of the nine proteins of the n-damo pathway were identified—indicating that n-damo is an active process occurring in situ in this habitat.
Project description:Deciphering the in situ activities of microorganisms is essential for understanding the biogeochemical processes occurring in complex environments. Here we used environmental metaproteomics to obtain information about the identity and activity of subsurface microbial populations in coal-tar-contaminated groundwater. The present study reports metaproteomic data showing high representation of Candidatus Methylomirabilis oxyfera in our study site’s subsurface microbial community. In addition, eight of the nine proteins of the n-damo pathway were identified—indicating that n-damo is an active process occurring in situ in this habitat.
Project description:The response of soil microbial community to climate warming through both function shift and composition reorganization may profoundly influence global nutrient cycles, leading to potential significant carbon release from the terrain to the atmosphere. Despite the observed carbon flux change in northern permafrost, it remains unclear how soil microbial community contributes to this ecosystem alteration. Here, we applied microarray-based GeoChip 4.0 to investigate the functional and compositional response of subsurface (15~25cm) soil microbial community under about one year’s artificial heating (+2°C) in the Carbon in Permafrost Experimental Heating Research site on Alaska’s moist acidic tundra. Statistical analyses of GeoChip signal intensities showed significant microbial function shift in AK samples. Detrended correspondence analysis and dissimilarity tests (MRPP and ANOSIM) indicated significant functional structure difference between the warmed and the control communities. ANOVA revealed that 60% of the 70 detected individual genes in carbon, nitrogen, phosphorous and sulfur cyclings were substantially increased (p<0.05) by heating. 18 out of 33 detected carbon degradation genes were more abundant in warming samples in AK site, regardless of the discrepancy of labile or recalcitrant C, indicating a high temperature sensitivity of carbon degradation genes in rich carbon pool environment. These results demonstrated a rapid response of northern permafrost soil microbial community to warming. Considering the large carbon storage in northern permafrost region, microbial activity in this region may cause dramatic positive feedback to climate change, which is important and necessary to be integrated into climate change models.