Beregova K. Bioconversion of industrial waste by surface-active substances Nocardia vaccinii IMV B-7405

The dissertation thesis is devoted to а development of technology of surface-active substances (surfactants) synthesized by Nocardia vaccinii IMV B-7405 using a mixture of industrial waste, such as crude glycerol and molasses, and to investigation of practical use of surfactants. The oil-oxidizing bacteria were isolated from the oil-polluted samples of soil and identified as Nocardia vacinii K-8 (IMV B-7405). The ability of these strain to synthesize the metabolites with surface-active and emulsifying properties was determined during the cultivation in medium with hydrophobic (n-hexadecane, liquid paraffin) and hydrophilic (glucose, ethanol) substrates was eatablished in previous studies. It was also determined that the chemical composition of surfactants synthesized by N. vacсinii K-8 on pure glycerol was a complex of neutral, glyco- and aminolipids. Glycolipids represented by trehalosediacelates and trehalosemycolates. Was showed that biosurfactant preparations of strain IMV В-7405 were effective against phytopathogenic bacteria. The possibility of replacing of pure glycerol for the surfactant biosynthesis by N.vaccinii IMV B-7405 with industry food waste (oil and fat industry, sugar, dairy industry, fried sunflower oil) was established. Thus, cultivation of N.vaccinii IMV B-7405 on fried sunflower oil and molasses was accompanied by increase of conditional concentrations of surfactants to 9.4 and 7.7 respectively compared with indexes on traditional substrate (pure glycerol). Аdding 0.1 % glucose into medium with fried sunflower oil (2 %) in exponential growth phase of N. vaccinii IMB B-7405 and using inoculum grown on molasses, was accompanied by increase concentrations of biosurfactants in 2.6 times compared with cultivation without precursors. It was established that after addition of 0.05 % fried sunflower oil into medium with molasses (2 %) and using inoculum grown on oil contained medium the amount of synthesized surfactants increased by 2.8 times in comparison with those without oil. The next it was showed that concentration of surfactants under cultivation of N.vacсinii IМВ В-7405 in crude glycerol was higher by 3 times as compared to that in a medium containing pure glycerol. Аdding low (0.05-0.1 %) concentration exogenous precursors (fumarate and citrate, glucose, sunflower oil) into medium with crude glycerol (4 %) allowed to increase synthesis raters of surfactants more by 17-44 %. It was established that the increasing concentration of inoculum from 10 to 15 % and sodium nitrate to 2-fold in medium cultivation of N.vacсinii IМВ В-7405 allowed to increase to 8.0 % content of grude glycerol. Under these conditions, the concentration of surfactants was 5.3 g/dm3, which is 3 times higher than the base medium with the same concentration of substrates.