Project description:Purpose: Identification of transcriptionally active genes in the unculturable community constituent, Smithella, during hexadecane degradation; Differential gene expression analysis of hexadecane-relevant genes acoss three different conditions; Extension of metatranscriptomic datasets to other community constituents to identify interspecies relationships.
Project description:Purpose: Identification of transcriptionally active genes in the unculturable community constituent, Smithella, during hexadecane degradation; Differential gene expression analysis of hexadecane-relevant genes acoss three different conditions; Extension of metatranscriptomic datasets to other community constituents to identify interspecies relationships. mRNA profiles were generated for this community across three different conditions (hexadecane-, butyric acid-, caprylic acid-degrading conditions) using a modified version of Nextera and sequenced using Illumina's Miseq platform.
Project description:The microbiome is an underappreciated contributor to intestinal drug metabolism with broad implications for drug efficacy and toxicity. While considerable progress has been made towards identifying the gut bacterial genes and enzymes involved, the role of environmental factors in shaping their activity remains poorly understood. Here, we focus on the gut bacterial reduction of azo bonds (R-N=N-R’), found in diverse chemicals in both food and drugs. Surprisingly, the canonical azoR gene in Escherichia coli was dispensable for azo bond reduction. Instead, azo reductase activity was controlled by the fumarate and nitrate reduction (fnr) regulator, consistent with a requirement for the anoxic conditions found within the gastrointestinal tract. Paired transcriptomic and proteomic analysis of the fnr regulon revealed that in addition to altering the expression of multiple reductases, FNR is necessary for the metabolism of L-Cysteine to hydrogen sulfide, enabling the degradation of azo bonds. Furthermore, we found that FNR indirectly regulates this process though the small non-coding regulatory RNA fnrS. Taken together, these results show how gut bacteria sense and respond to their intestinal environment to enable the metabolism of chemical groups found in both dietary and pharmaceutical compounds.
Project description:Chemoautotrophic bacteria from the SUP05 clade often dominate anoxic waters in marine oxygen minimum zones (OMZs) where reduced sulfur can fuel carbon fixation and denitrification. Some members of the SUP05 clade are facultative aerobes that thrive at the boundaries of OMZs where they experience fluctuations in dissolved oxygen (DO). The degree to which SUP05 contribute to nitrate reduction in these regions depends on their sensitivity to oxygen. We evaluated growth and quantified differences in gene expression in Ca. T. autotrophicus strain EF1 from the SUP05 clade under high DO (22 μM), anoxic, and low DO (3.8 μM) concentrations. We show that strain EF1 cells respire oxygen and nitrate and that cells have higher growth rates, express more genes, and fix more carbon when oxygen becomes available for aerobic respiration. Evidence that facultatively aerobic SUP05 are more active and respire nitrate when oxygen becomes available at low concentrations suggests that they are an important source of nitrite across marine OMZ boundary layers.
