ABSTRACT
It has been established that in cells of Nocardia vaccinii IMB B-7405 (surfactant producer) glucose catabolism is performed through pentose phosphate cycle as well as through gluconate (activity of NAD+-dependent glucose-6-phosphate dehydrogenase and FAD+-dependent glucose dehydrogenase 835 ± 41 and 698 ± 35 nmol.min-1.mg-1 of protein respectively). 6-Phosphogluconate formed in the gluconokinase reaction is involved in the pentose phosphate cycle (activity of constitutive NADP+-dependent 6-phosphogluconate dehydrogenase 357 ± 17 nmol.min-1.mg-1 of protein). Glycerol catabolism to dihydroxyacetonephosphate (the intermediate of glycolysis) may be performed in two ways: through glycerol-3-phosphate (glycerol kinase activity 244 ± 12 nmol.min-1.mg-1 of protein) and through dihydroxyacetone. Replenishment of the C4-dicarboxylic acids pool in N. vaccinii IMV B-7405 grown on glucose and glycerol occurs in the phosphoenolpyruvate(PEP)carboxylase reaction (714-803 nmol.min-1.mg-1 of protein). 2-Oxoglutarate was involved in tricarboxylic acid cycle by alternate pathway with the participation of 2-oxoglutarate synthase. The observed activity of both key enzymes of gluconeogenesis (PEP-carboxykinase and PEP-synthase), trehalose phosphate synthase and NADP+-dependent glutamate dehydrogenase confirmed the ability of IMV B-7405 strain to the synthesis of surface active glycoand aminolipids, respectively.
Subject(s)
Bacterial Proteins/metabolism , Glucose/metabolism , Glycerol/metabolism , Nocardia/metabolism , Citric Acid Cycle/physiology , Dihydroxyacetone/metabolism , Dihydroxyacetone Phosphate/metabolism , Gluconates/metabolism , Gluconeogenesis/physiology , Glucose 1-Dehydrogenase/metabolism , Glucosephosphate Dehydrogenase/metabolism , Glutamate Dehydrogenase (NADP+)/metabolism , Glycerophosphates/metabolism , Glycolysis/physiology , Ketoglutaric Acids/metabolism , Ketone Oxidoreductases/metabolism , Pentose Phosphate Pathway/physiology , Phosphoenolpyruvate/metabolism , Phosphoenolpyruvate Carboxykinase (ATP)/metabolism , Phosphoenolpyruvate Carboxylase/metabolism , Phosphogluconate Dehydrogenase/metabolism , Phosphotransferases (Alcohol Group Acceptor)/metabolism , Phosphotransferases (Paired Acceptors)/metabolismABSTRACT
The possibility of replacing glucose and pure glycerol in mixed substrates for surtace-active substances (SAS, biosurfactants) biosynthesis of Nocardia vaccinii IMB B-7405 on molasses (sugar production waste) and crude glycerol (by-product of biodiesel production) was established. It was established that the increasing concentration of crude glycerol to 6% in mixture with 1.0% molasses was accompanied by increase of amount of SAS synthesized more than twice, and the increasing content of molasses to 3.0% in mixture with 1.0% crude glycerol--by some decrease in the level of surfactant as compared to that in a medium containing 1.0% monosubstrates. It was shown that the increasing concentration of sodium nitrate to 2-fold in medium cultivation of N. vaccinii IMB B-7405 allowed to increase to 7.0% content of grude glycerol in mixture with 1.0% molasses. Under such conditions of cultivation concentration of exocellular SAS synthesized was 7,5 g/l, that to 1,3 fold higher than in basic medium with a lower content of nitrogen source.
