Project description:Previous analysis of gene transcript levels of Geobacter species in groundwater during in situ bioremediation of a uranium-contaminated aquifer detected expression of genes encoding superoxide dismutase (sodA) and cytochrome d ubiquinol oxidase (cydA), proteins known to be involved in the response to oxidative stress in other microorganisms. In order to further elucidate gene expression patterns that could be attributed to oxygen exposure, G. uraniumreducens was grown with acetate as the electron donor and fumarate as the electron acceptor in the presence of oxygen and compared to non-oxygen treated cultures.
Project description:A Caulobacter sp. isolate was recovered from the dialysis fluid of a patient undergoing peritoneal dialysis. Bacterial identification included electron microscopy and 16S rDNA sequencing. To our knowledge, this is the first report of human Caulobacter infection. Special growth requirements suggest that Caulobacter spp. may be overlooked in the clinical microbiology laboratory.
Project description:To test the effects of hypoxia on transcription in Caulobacter crescentus, we cultured cells in a New Brunswick bioreactor under controlled conditions. Prior to innoculation, the medium was bubbled with laboratory air at maximum flow and stirred at 300 rpm for 2 hours. After this period, the medium was considered saturated with air and the oxygen probe was set to 100%. Untreated cultures were grown in air-saturated complex medium at 30 degrees C to OD660=0.5 at pH=7 (continuous air-bubbling; 300 rpm stirring). At cell harvest in aerated culture, the dissolved oxygen probe remained above 98%. To subject cells to hypoxia, culture at OD660=0.5, pH=7 was sparged continuously with nitrogen gas; the dissolved oxygen level as measured by the gas probe dropped from 100% to 0% over the course of 5 minutes under this condition. Hypoxic cultures were continually stirred and bubbled with nitrogen for another 20 minutes after the dissolved gas probe read 0%. Hypoxic cells were then harvested for RNA isolation. Four independent biological samples are included in this study. Two batches of cells were subjected to 20 minutes of hypoxia in a bioreactor; two cell batches were highly aerated.
Project description:To test the effects of hypoxia on transcription in Caulobacter crescentus, we cultured cells in a New Brunswick bioreactor under controlled conditions. Prior to innoculation, the medium was bubbled with laboratory air at maximum flow and stirred at 300 rpm for 2 hours. After this period, the medium was considered saturated with air and the oxygen probe was set to 100%. Untreated cultures were grown in air-saturated complex medium at 30 degrees C to OD660=0.5 at pH=7 (continuous air-bubbling; 300 rpm stirring). At cell harvest in aerated culture, the dissolved oxygen probe remained above 98%. To subject cells to hypoxia, culture at OD660=0.5, pH=7 was sparged continuously with nitrogen gas; the dissolved oxygen level as measured by the gas probe dropped from 100% to 0% over the course of 5 minutes under this condition. Hypoxic cultures were continually stirred and bubbled with nitrogen for another 20 minutes after the dissolved gas probe read 0%. Hypoxic cells were then harvested for RNA isolation.
Project description:Four stable and robust TCE-dechlorinating microbial communities were enriched from TCE-contaminated groundwater under four different conditions exploring two parameters, high and low methanogenic activity (Meth and NoMeth), with and without vitamin B12 supplement (MethB12 and NoMethB12, Meth and NoMeth, respectively). Identical amounts of lactate (2.7 mmol) and TCE (20 μl) were supplied as electron donor and electron acceptor. All four cultures were capable of reductively dechlorinating TCE to VC and ethene. Genomic DNA of the four enrichments was applied on a quad-Dhc-genome microarray in order to characterize the gene content of Dehalococcoides species present in the four enrichments