[Intensification of surfactants synthesis by Nocardia vaccinii K-8 on crude glycerol].

The authors studied the effect of components of crude glycerol (potassium and sodium salts, ethanol, methanol) - the by-products of biodiesel production on formation of surfactants (surface-active substances, SAS) by Nocardia vaccinii K-8, as well as possibility to intensify the SAS synthesis by the strain K-8 on crude glycerol in the presence ofbiosynthesis precursors (glucose, sun-flower oil, organic substances). It has been established that the introduction of potassium (sodium) chloride in concentration 2.5 % and ethanol (methanol) in concentration 0.3 % into the medium with refined glycerol (1 %) was accompanied by the 14-1.7-fold increase of conditional SAS concentration as compared with indices on the medium without adding salts and alcohols. Under cultivation conditions of strain K-8 on the medium with crude glycerol the conditional SAS concentration was 3-fold higher than on the medium with refined substrate. Introduction of glucose (0.05 %), sun-flower oil (0.05 %), fumarate and citrate (0.1 %) during the stationary growth phase of N. vaccinii K-8 into the medium with crude glycerol (2.2%) was accompanied by the increase in the amount of synthesized SAS h by 17-44 % compared with cultivation of bacteria on the medium without precursors.

[Effect of growth factors and some microelements on biosurfactant synthesis of Acinetobacter calcoaceticus IMV B-7241].

The effect of yeast autolysate and microelements on synthesis of surface-active substances (SAS, biosurfactants) was investigated under cultivation of Acinetobacter calcoaceticus IMV B-7241 on various carbon substrates (n-hexadecane, ethanol, glycerol). The authors have shown a possibility to substitute the yeast autolysate and microelement mixture in the composition of ethanol- and n-hexadecane-containing media by copper sulfate (0.16 micromol/l) and iron sulfate (3.6 micromol/l), and in the medium with glycerol by 0.21 mmol/l of KCl, 38 micromol/l of zinc sulfate and 0.16 micromol/l of copper sulfate. Under such conditions of cultivation of the strain IMV B-7241 the SAS concentration exceeded that on the initial media, which contained the yeast autolysate and microelements, 1.2-1.6 times. The authors have also established the activating effect of low (0.01 mM) concentrations of Fe2+ on activity of the enzymes of biosynthesis of surface-active amino- (NADP-dependent glutamate dehydrogenase) and glycolipids (phosphoenolpyruvate(PhEP)-synthetase, PhEP-carboxykinase), as well as of anaplerotic reaction(PhEP-carboxylase). A necessity to introduce zinc cations into glycerol-containing medium is determined by their stimulating effect on activity of 4-dinitroso-N,N-dimethylaniline-dependent alcohol dehydrogenase--one of the enzymes of this substrate catabolism in A. calcoaceticus IMV B-7241.