Maslovska O. Antioxidant defense and fatty acid composition of Desulfuromonas acetoxidans IMV B-7384 under the influence of ferric (III) citrate

In the thesis the influence of ferric (III) citrate as a factor that causes oxidative damage of Desulfuromonas acetoxidans ІМV В-7384 cells is investigated for the first time. Chosen concentrations of ferric (III) citrate allowed to estimate the influence of metal salt at the slight inhibition of culture growth (10 %) and at the increasing of inhibitory effect up to 50–60 %. It was determined that oxidation of cell lipids of investigated bacteria is occured by free radical mechanism that is observed by the increasing of conjugated dienes content of the cells. At the influence of metal salt D. acetoxidans ІМV В-7384 cells accumulate significant amounts of lipid peroxidation products, in particular lipid hydroperoxides and thiobarbituric acid reactive substances. It was shown that under the influence of ferric (III) citrate protein molecules are also damaged as it is evidenced by the increasing of content of carbonyl groups in proteins. For the first time investigated ATP-hydrolase activity of D. acetoxidans ІМV В-7384 under the influence of different concentrations of ferric (III) citrate is investigated for the first time. As a result of investigation of enzymatic branch of antioxidant defense system of D. acetoxidans ІМV В-7384 it was found that important role in antioxidant defense is played by the components of glutathione system, in particular glutathione peroxidase, glutathione-S-transferase and glutathione reductase except superoxide dismutase and catalase. Also reduced glutathione is involved into antioxidant defense of these bacteria. For the first time the fatty acids composition of D. acetoxidans ІМV В-7384 is determined and it changes are analyzed under the influence of ferric (III) citrate. It was found that changes of fatty acid composition of D. acetoxidans ІМV В-7384 cells occur for maintenance the appropriate level of cytoplasmic membrane fluidity as the response to the influence of ferric ions. Indices of membrane fluidity of D. acetoxidans ІМV В-7384 cells under the influence of ferric (III) citrate have been analyzed. It was shown that regulation of lipid saturation of D. acetoxidans ІМV В-7384 occurs on biosynthetic level (by synthesis of branched fatty acids) and postsynthetic (by formation of fatty acids with cyclopropane ring). Electron donors have been selected for electric current generation by D. acetoxidans ІМV В-7384 in a microbial fuel cell. Compounds that metabolism is accompanied by the release of reduced equivalents were determined to be the most effective electron donors. Obtained results develop current understanding of the influence of heavy metal ions, in particular ferric ions, on the cells of sulfur-reducing metal-reducing microorganisms and their defense mechanisms.