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Документ Some characteristics of central metabolism in Acinetobacter sp. grown on ethanol(2003) Pirog, Tatiana; Kuzminska, Yu.Ethanol-grown cells of the mutant Acinetobacter sp. strain 1NG, incapable of producing exopolysaccharides, were analyzed for the activity of enzymes of the tricarboxylic acid (TCA) cycle and some biosynthetic pathways. In spite of the presence of both key enzymes (isocitrate lyase and malate synthase) of the glyoxylate cycle, these cells also contained all enzymes of the TCA cycle, which presumably serves biosynthetic functions. This was evident from the high activity of isocitrate dehydrogenase and glutamate dehydrogenase and the low activity of 2-oxoglutarate dehydrogenase. Pyruvate was formed in the reaction catalyzed by oxaloacetate decarboxylase, whereas phosphoenolpyruvate (PEP) was synthesized by the two key enzymes (PEP carboxykinase and PEP synthase) of gluconeogenesis. The ratio of these enzymes was different in the exponential and the stationary growth phases. The addition of the C4-dicarboxylic acid fumarate to the ethanolcontaining growth medium led to a 1.5- to 2-fold increase in the activity of enzymes of the glyoxylate cycle, as well as of fumarate hydratase, malate dehydrogenase, PEP synthase, and PEP carboxykinase (the activity of the latter enzyme increased by more than 7.5 times). The data obtained can be used to improve the biotechnology of production of microbial exopolysaccharide ethapolan on C2-substrates.Документ Peculiarities of C2-Metabolism and Intensification of the Synthesis of Surface-Active Substances in Rhodococcus erythropolis EK-1 Grown in Ethanol(2008) Pirog, Tatiana; Korzh, Yuliya; Shevchuk, Tetiana; Tarasenko, D.Oxidation of ethanol, acetaldehyde, and acetate in Rhodococcus erythropolis EK-1, producer of surface-active substances (SAS), is catalyzed by N,N-dimethyl-4-nitrosoaniline (DMNA)-dependent alcohol dehydrogenase, NAD+/NADP+-dependent dehydrogenases (optimum pH 9.5), and acetate kinase/acetyl-CoAsynthetase, respectively. The glyoxylate cycle and complete tricarboxylic acid cycle function in the cells of R. erythropolis EK-1 growing on ethanol; the synthesis of phosphoenolpyruvate (PEP) is provided by the two key enzymes of gluconeogenesis, PEP carboxykinase and PEP synthetase. Introduction of citrate (0.1%) and fumarate (0.2%) into the cultivation medium of R. erythropolis EK-1 containing 2% ethanol resulted in the 1.5- and 3.5-fold increase in the activities of isocitrate lyase and PEP synthetase (the key enzymes of the glyoxylate cycle and gluconeogenesis branch of metabolism, respectively) and of lipid synthesis, as evidenced by the 1.5-fold decrease of isocitrate dehydrogenase activity. In the presence of fumarate and citrate, the indices of SAS synthesis by strain R. erythropolis EK-1 grown on ethanol increased by 40–100%. Окисление этанола у штамма Rhodococcus erythropolis ЭК-1 – продуцента поверхностно-активных веществ (ПАВ), осуществляется 4-нитрозо-N,N-диметиланилин (НДМА)-зависимой алкогольдегидрогеназой, окисление ацетальдегида – НАД+- и НАДФ+-зависимыми дегидрогеназами с оптимумом рН 9.5, окисление ацетата – ацетаткиназой и ацетил-КоА-синтетазой. При росте на этаноле в клетках R. erythropolis ЭК-1 функционирует как глиоксилатный цикл, так и полный цикл трикарбоновых кислот, синтез фосфоенолпирувата (ФЕП) обеспечивается двумя ключевыми ферментами глюконеогенеза – ФЕП-карбоксикиназой и ФЕП-синтетазой. Внесение в среду культивирования R. erythropolis ЭК-1, содержащую 2 % этанола, цитрата (0.1 %) и фумарата (0.2 %) сопровождалось усилением глюконеогенеза, что подтверждается повышением в 1.5 и 3.5 раза активности изоцитратлиазы и ФЕП-синтетазы (ключевых ферментов глиоксилатного цикла и глюконеогенетической ветви обмена веществ соответственно), а также синтеза липидов, о чем может свидетельствовать снижение в 1.5 раза активности изоцитратдегидрогеназы. В присутствии фумарата и цитрата показатели синтеза ПАВ штаммом R. erythropolis ЭК-1 на этаноле повышались на 40–100 %.Документ Specific features of the synthesis of the exopolysaccharide ethapolan on a mixture of energy-deficient growth substrates(2007) Pirog, Tatiana; Vysyatetska, Nadezhda; Korzh, YuliyaIntensification of the synthesis of the microbial exopolysaccharide ethapolan by Acinetobacter sp. B-7005 was shown to occur on a mixture of energy-deficient growth substrates (acetate + glucose). When the bacterium grew on the substrate mixture, both substrates were utilized simultaneously; acetate was taken up by means of active transport at the expense of the energy of the proton-motive force. When acetate was present in the form of a sodium salt, the activities of acetyl-CoA synthetase and phosphoenolpyruvate synthetase (the key enzyme of gluconeogenesis) were tenfold higher than in the presence of potassium acetate, and the indexes of ethapolan synthesis were two times higher. The positive effect of Na+ on ethapolan synthesis is supposed to consist in the creation of ion gradients on the membrane, necessary for the generation of the proton-motive force. Simultaneous functioning of the glyoxylate cycle and pyruvate carboxylase reaction, as well as an increase in the activity of isocitrate lyase, malate synthase, and phosphoenolpyruvate synthetase, provide evidence of increased gluconeogenesis in the presence of the acetate + glucose mixture (as compared to gluconeogenesis on the corresponding monosubstrates).