Project description:Sulfate-reducing bacteria (SRB) are terminal members of any anaerobic food chain. For example, they critically influence the biogeochemical cycling of carbon, nitrogen, sulfur, and metals (natural environment) as well as the corrosion of civil infrastructure (built environment). The United States alone spends nearly $4 billion to address the biocorrosion challenges of SRB. It is important to analyze the genetic mechanisms of these organisms under environmental stresses. The current study uses transcriptome-wide marker gene panel mapping to decipher the stress mechanisms in SRB. This project contains 3 control samples and 6 test samples of RNA-seq data of Oleidesulfovibrio alaskensis strain G20, exposed to pristine copper and graphene-coated copper.
Project description:We microdissected each embryo region from 6-micron paraffin sections using the Leica AS LMD system to identify all genes active in different embryo region of an SRB seed containing globular-stage embryos. Keywords: cell type comparison
Project description:Competition among nitrate reducing bacteria (NRB) and sulfate reducing bacteria (SRB) for resources in anoxic environments is generally thought to be governed largely by thermodynamics. It is now recognized that intermediates of nitrogen and sulfur cycling (e.g., hydrogen sulfide, nitrite, etc.) can also directly impact NRB and SRB activities in freshwater, wastewater and sediment, and therefore may play important roles in competitive interactions. Here, using Intrasporangium calvum C5 as a model NRB, we performed comparative transcriptomic and metabolomic analyses to demonstrate that the reduced sulfur compounds cysteine and sulfide differentially inhibit respiratory growth on nitrate, and that inhibition by each can be selectively relieved by a specific carbon source. These findings provide mechanistic insights into the interplay and stratification of NRBs and SRBs in diverse environments.
Project description:Copper (Cu) is an essential micronutrient required as a co-factor in the catalytic center of many enzymes in bacteria. However, excess Cu is hazardous and can generate pleiotropic effects. Cu has been the metal of choice for piping used in household water distribution systems. Due to its leaching from pipelines, Cu is present at an elevated concentration in groundwater and in soil which is of public health concern. Sulfate-reducing bacteria (SRB) have been demonstrated to remove toxic levels of Cu. However, reports on the toxicity of Cu towards SRB have primarily focused on the degree of toxicity and subsequent elimination. In this study, we show in detail the Cu(II) stress-related effects on a model sulfate reducing bacteria, Desulfovibrio alaskensis G20. Cu(II) stress effects were assessed as alterations in the transcriptome through RNA-Seq at varying Cu(II) concentrations (5µM and 15µM). In the pairwise comparison of control vs 5µM, 61.43% of genes were downregulated and 38.57% genes were upregulated. In 15µM vs control, 49.51% genes were downregulated, and 50.5% genes were upregulated. The results indicated that the expression of inorganic ion transporters and translation machinery was massively modulated. Moreover, changes in important biological processes such as DNA transcription and signal transduction were observed at high Cu(II) concentration. In addition, metabolomics analysis indicated the effect of certain organic acids and amino acids in cellular metal buffering system and reducing oxidative damage to cells. These results will help us better understand the mechanism of Cu(II) stress response and provide avenues for future research.
Project description:Sulfate-reducing bacteria (SRB) colonize the guts of ~50% of humans. We used genome-wide transposon mutagenesis and insertion-site sequencing (INSeq), RNA-Seq, plus mass spectrometry to characterize genetic and environmental factors that impact the niche of Desulfovibrio piger, the most common SRB in a surveyed cohort of healthy USA adults. Gnotobiotic mice were colonized with an assemblage of sequenced human gut bacterial species with or without D. piger and fed diets with different levels and types of carbohydrates and sulfur sources. Diet was a major determinant of functions expressed by this artificial 9-member community and of the genes that impact D. piger fitness; the latter includes high- and low-affinity systems for utilizing ammonia, a limiting resource for D. piger in mice consuming a polysaccharide-rich diet. While genes involved in hydrogen consumption and sulfate reduction are necessary for its colonization, varying dietary free sulfate levels did not significantly alter levels of D. piger, which can obtain sulfate from the host in part via cross-feeding mediated by Bacteroides-encoded sulfatases. Chondroitin sulfate, a common dietary supplement, increased D. piger and H2S levels without compromising gut barrier integrity. A chondroitin sulfate-supplemented diet together with D. piger impacted the assemblage’s substrate utilization preferences, allowing consumption of more reduced carbon sources, and increasing the abundance of the H2-producing Actinobacterium, Collinsella aerofaciens. Our findings provide genetic and metabolic details of how this H2-consuming SRB shapes the responses of a microbiota to diet ingredients, and a framework for examining how individuals lacking D. piger differ from those that harbor it.