Korzh J. Regulation of C2-metabolism in an Аcinetobacter sp. В-7005 - producer of microbial exopolysaccharide ethapolan

The thesis is devoted to study of the basic stages of С2-compounds assimilation in Аcinetobacter sp. В-7005, to reveal "bottleneck" of С2-metabolism and to develop of approaches to their removal to improve process of microbial exopolysaccharide (EPS) ethapolan synthesis. The ethanol-grown cells of Acinetobacter sp. В-7005 were analyzed for the activity of С2-metabolism key enzymes, tricarboxylic acids cycle, anaplerotic and some biosynthetic pathways enzymes. Ethanol metabolism in Acinetobacter sp. В-7005 is limited by the rate of acetate assimilation in a reaction catalyzed by acetyl-CoA-synthetase, was shown. Effects of ions (sodium, potassium and magnesium), intermediates of ethanol and acetaldehyde oxidation (NADH and NADPH) on this enzyme were studied (sodium, NADH and NADPH inhibited acetyl-CoA-synthetase; potassium and magnesium acted enzyme activators). The exogenic acetate addition into ethanol containing medium abolished limitation of С2-metabolism in Acinetobacter sp. В-7005. Basing onthe investigations of С2-metabolism regulation the cultivation conditions were developed which allowed to increase the acetyl-CoA-synthetase activity in Acinetobacter sp. В-7005. Ethapolan synthesized under these conditions was characterized by high level of acylation (3 - 15%). Molecular mass of this polysaccharide was 1,5 million and was not changed during purification. Improved reological properties of ethapolan were associated with high molecular mass and increasing fatty acids content.