Project description:Negative-ionization DDA metabolomics data of anaerobic SDC-9 cultures, which perform dechlorination of chlorinated ethenes for bioremediation
Project description:Positive-ionization DDA metabolomics data of anaerobic SDC-9 cultures, which perform dechlorination of tetrachloroethene for bioremediation
Project description:Positive-ionization DDA metabolomics data of anaerobic SDC-9 cultures, which perform dechlorination of chlorinated ethenes for bioremediation
Project description:A comparative transcriptome approach was used to assess genes involved in metabolism and pathogenesis that are specifically activated during anaerobic growth of the spore-forming food-borne human pathogen Bacillus cereus ATCC 14579. Growth under anaerobic conditions in Brain Heart Infusion broth revealed a reduced growth rate and a lower yield as compared to that under aerobic conditions. Comparative transcriptome analysis of cells harvested at early- and mid-exponential growth phase, transition phase and stationary phase, subsequently showed hundreds of genes to be induced under anaerobic condition. These included novel genes identified for anaerobic growth of B. cereus, encoding metabolic pathways, such as the arginine deiminase pathway (ArcABDC), a formate dehydrogenase (FdhF) and a pyruvate fomate lyase (Pfl), and alternative respiratory proteins, such as arsenate reductases. Furthermore, the nitrosative stress response was induced in the anaerobic transition phase of growth, conceivably due to the production of nitric oxide as a by-product of nitrite and nitrate respiration. Notably, both hemolytic enzyme and enterotoxin encoding genes were activated in different oxygen limiting conditions, i.e. hemolytic enzyme encoding genes were induced during anaerobic growth, whereas enterotoxin encoding genes were induced in the transition and stationary phase of aerobic cultures reaching a high cell density. These data point to metabolic rearrangements, stress adaptation and activation of the virulent status of B. cereus under anaerobic conditions, such as encountered in the human GI-tract. Keywords: time course, anaerobic growth
Project description:Anaerobic activation of benzene is expected to represent a novel biochemistry of environmental significance but research into the mechanisms has been stymied by a lack of a genetically tractable pure culture which unequivocally does not use molecular oxygen to activate benzene. Geobacter metallireducens grew in a medium in which benzene was the sole electron donor and Fe(III) was the sole electron acceptor with a stoichiometry of benzene loss and Fe(III) reduction consistent with benzene oxidation to carbon dioxide coupled with Fe(III) reduction. Phenol labeled with 18O was produced when the medium was labeled with H218O, as expected for a true anaerobic conversion of benzene to phenol. Gene expression patterns indicated that benzene was metabolized through a phenol intermediate rather than benzoate or toluene. Deletion of ppcB, which encodes a subunit of the phenylphosphate carboxylase, an enzyme required for phenol metabolism, inhibited metabolism of benzene. Deleting genes specific for benzoate or toluene metabolism did not. Comparison of gene expression patterns in cells grown on benzene versus cells grown on phenol revealed genes specifically expressed in benzene-grown cells. Deletion of one of these, Gmet_3376, inhibited anaerobic benzene oxidation, but not the metabolism of phenol, benzoate, or toluene. The availability of a genetically tractable pure culture that can anaerobically convert benzene to phenol with oxygen derived from water should significantly accelerate elucidation of the mechanisms by which benzene can be activated in the absence of molecular oxygen. Total RNA from three separate cultures of G. metallireducens grown with 250 µM benzene three separate cultures of G. metallireducens grown with 500 µM phenol three separate cultures of G. metallireducens grown with 1 mM benzoate three separate cultures of G. metallireducens grown with 500 µM toluene three separate cultures of G. metallireducens grown with 10 mM acetate were used to study [1] Anaerobic oxidation of benzene by G. metallireducens (Benzene vs. acetate, Benzene vs. benzoate, Benzene vs. phenol, Benzene vs. toluene) [2] Anaerobic oxidation of benzoate by G. metallireducens (Benzoate vs. acetate) [3] Anaerobic oxidation of phenol by G. metallireducens (Phenol vs. acetate) [4] Anaerobic oxidation of toluene by G. metallireducens (Toluene vs. acetate) Each chip measures the expression level of 3,627 genes from G. metallireducens DSM 7210 with nine 45-60-mer probe pairs (PM/MM) per gene, with three-fold technical redundancy.
Project description:Escherichia coli is a metabolically versatile bacterium that is able to grow in the presence and absence of oxygen. Several previous transcript-profiling experiments have compared separate anaerobic and aerobic cultures. Here, for the first time, the process of adaptation was investigated by determining changes in transcript profiles when anaerobic steady-state cultures were perturbed by the introduction of air. Escherichia coli strain MG1655 was grown in a New Brunswick Scientific Bioflow 1000 fermentation vessels (1.8 l capacity) with culture agitation speed constant at 400 rpm and the temperature maintained at 37 °C. Oxygen levels were monitored using galvanic oxygen electrodes while the pH was maintained at 7.2 ±0.2 by automatic titration with sterile KOH. Evans defined medium was used as the growth medium with glucose (30 mM) as the carbon source with the dilution rate being 0.2 h-1. Anaerobic cultures were maintained by sparging the chemostat with oxygen-free nitrogen (95 %) and carbon dioxide (5 %) (0.2 l min-1). The switch to aerobic conditions was achieved by sparging the culture with air (2.0 l min-1) in place of the above gas mix. After a period of 5, 10, 15 and 60 min exposure to air, cells were harvested directly into RNA Protect (Qiagen) to stabilize RNA before total RNA purification using Qiagen’s Rneasy Midi kit as recommended by manufacturer’s instructions. Keywords: time course response to air
Project description:The transcriptional response of Haemophilus ducreyi to anaerobiosis was determined over the course of 18 h. Cells were collected from aerobic and anaerobic cultures at 4, 8, or 18 hours .