Project description:Molecular analysis of DNA repair mechanisms in Mycobacterium tuberculosis. Bacteria exposed to mitomycin C, UV irradiation or hydrogen perxoxide treatment for up to 12 hours. Keywords: repeat sample
Project description:Photosynthetic microbes can produce the clean-burning fuel hydrogen using one of nature’s most plentiful resources, sunlight 1,2. Anoxygenic photosynthetic bacteria generate hydrogen and ammonia during a process known as biological nitrogen fixation. This reaction is catalyzed by the enzyme nitrogenase and consumes nitrogen gas, ATP and electrons 3. One bacterium, Rhodopseudomonas palustris, has a remarkable ability to obtain electrons from green plant-derived material 4,5 and to efficiently absorb both high and low intensity light energy to form ATP 6. Manipulating R. palustris or a similar organism to produce hydrogen commercially will require us to identify all its genes that contribute to hydrogen production and to understand how this process is regulated in cells. Here we describe mutant strains in which metabolism is redirected such that hydrogen production is uncoupled from nitrogen fixation. Our data indicate that three different single amino acid changes in the transcriptional regulator NifA each yielded strains that produced hydrogen even in the presence of the repressing nitrogen source ammonium and in the absence of specific inducing metabolic signals. We used the mutants to show that, in addition to nitrogenase genes, 18 genes outside of the nitrogenase gene cluster may contribute to hydrogen production. Some of these genes are likely involved in efficient ATP acquisition and in channeling electrons to nitrogenase for reduction of protons to molecular hydrogen. Our results demonstrate that photosynthetic bacteria can be genetically manipulated for sustained production of pure hydrogen in a variety of cultivation conditions in the absence of oxygen, nitrogen or other gases as long as light and an electron donor are supplied. Keywords: Comparison of transcriptome profiles
Project description:We report 293 Neisseria gonorrhoeae genes that show differential transcript abundance in response to 15 mM hydrogen peroxide treatment by RNA-Seq. We analyze the major physiological functional groups of genes affected by hydrogen peroxide exposure. In addition, we analyze which genes in our hydrogen peroxide-responsive set of genes belong to major known transcriptional regulatory circuits like iron homeostasis, anaerobiosis and others. We annotate which of the 293 hydrogen peroxide-responsive genes belong to operons. We annotate global transcriptional start sites and identify transcriptional start sites that are only present in hydrogen peroxide-treated bacteria. We validate the RNA-Seq data for a subset of representative genes by RT-qPCR and whether transcript abundance in this same subset of genes differs upon treatement with other reactive oxygen species encountered during infection, like organic peroxide, super oxide anion, and bleach.
Project description:Photosynthetic microbes can produce the clean-burning fuel hydrogen using one of natureâ??s most plentiful resources, sunlight 1,2. Anoxygenic photosynthetic bacteria generate hydrogen and ammonia during a process known as biological nitrogen fixation. This reaction is catalyzed by the enzyme nitrogenase and consumes nitrogen gas, ATP and electrons 3. One bacterium, Rhodopseudomonas palustris, has a remarkable ability to obtain electrons from green plant-derived material 4,5 and to efficiently absorb both high and low intensity light energy to form ATP 6. Manipulating R. palustris or a similar organism to produce hydrogen commercially will require us to identify all its genes that contribute to hydrogen production and to understand how this process is regulated in cells. Here we describe mutant strains in which metabolism is redirected such that hydrogen production is uncoupled from nitrogen fixation. Our data indicate that three different single amino acid changes in the transcriptional regulator NifA each yielded strains that produced hydrogen even in the presence of the repressing nitrogen source ammonium and in the absence of specific inducing metabolic signals. We used the mutants to show that, in addition to nitrogenase genes, 18 genes outside of the nitrogenase gene cluster may contribute to hydrogen production. Some of these genes are likely involved in efficient ATP acquisition and in channeling electrons to nitrogenase for reduction of protons to molecular hydrogen. Our results demonstrate that photosynthetic bacteria can be genetically manipulated for sustained production of pure hydrogen in a variety of cultivation conditions in the absence of oxygen, nitrogen or other gases as long as light and an electron donor are supplied. Transcriptome profile of wild type (CGA009) growing photosynthetically in the presence of amonium an acetate was compare with that of 4 different mutants (CGA570, CGA571, CGA572 and CGA574). We did 2 biological replicates per strain.
Project description:Stress survival tactics in bacteria utilize the up- and down-regulation of stress response genes. In bacteria that lack classical stress response genes for oxidative stress, other cellular systems can be used for cell survival. We used custom microarrays to study the regulation of genes in Bifidobacterium animalis ssp. lactis strains to oxidative stress to elucidate novel stress response mechanisms. Bifidobacterium cells were grown to late log phase then harvested and exposed to a sub-lethal level of hydrogen peroxide. Samples were taken at 5 and 20 mins for RNA extraction and hybridization on Affymetrix microarrays. Controls were prepared for each time point which recieved no hydrogen peroxide treatment.
Project description:Determine in the context of a controlled crossover diet-intervention trial the role of taurocholic acid metabolism by gut bacteria in African American subjects at elevated risk for colorectal cancer (CRC). Two isocaloric diets, an animal-based diet high in taurine and saturated fat (HT-HSAT) and a plant-based, low in taurine and low saturated fat (LT-LSAT) will be used to determine the extent to which the relationship between diet (independent variable) and mucosal markers of CRC risk including epithelial proliferation, oxidative stress, DNA damage, and primary and secondary bile acid pools and biomarkers of inflammation (dependent variables) is explained by the abundance of sulfidogenic bacteria and hydrogen sulfide (H2S) concentrations &/or deoxycholic acid (DCA) and DCA-producing bacteria clostridium scindens (mediator variables).