Intensification of surfactants’ synthesis by Rhodococcus erythropolis IMV Ac-5017, Acinetobacter calcoaceticus IMV B-7241 and Nocardia vaccinii K-8 on fried oil and glycerol containing medium

Searching for the ways to process waste has become very topical today. Biotechnology is one of the most environmentally attractive methods, which has the ability to solve the problem of waste utilization and to produce the valuable microbial products, for example biosurfactants. We concluded that fried sunflower oil, oil-containing wastes (soapstock) and glycerol can be used for biosurfactant production by Rhodococcus erythropolis IMV Ac-5017, Acinetobacter calcoaceticus IMV B-7241 and Nocardia vaccinii K-8. Glucose addition (0.1%) into the medium with fried oil (2 vol.%) led to a 4-fold increase of final surfactant concentration (6.8 g/L). The simultaneous addition of fumarate and citrate (0.01–0.2%) into the IMV B-7241 and K-8 strains’ cultivating medium was accompanied by an increase of the exocellular biosurfactant quantity by 2–2.5-fold compared to the cultivation without organic acids. An increase in surfactant concentration of IMV B-7241 strain was the result of the simultaneous functioning of two anaplerotic pathways, also resulting in a 3–5-fold increase in activity of biosynthesis enzymes. Cultivating on a mixture of glycerol and n-hexadecane (0.5–1.0 vol.%) led to a 1.5–3-fold increasing surfactant synthesis. Biosurfactant preparations of IMV B-7241 (0.15–0.22 mg/mL) and IMV Ac-5017 (0.61–2.1 mg/mL) strains were effective against Escherichia coli IEM-1 (67% of cell loss), and vegetative (45–100% of cell loss) and spore (75% of spore loss) cells of Bacillus subtilis BT-2.

► The possibility of waste use for biosurfactant production was determined. ► Presence of fumarate and citrate intensified biosurfactant synthesis by 2.5-fold. ► C4-dicarboxylic acids enhanced activity of surfactant biosynthesis enzymes. ► Cultivation on mixture of substrates resulted in increased surfactants quantity. ► Surfactants were effective against Escherichia coli IEM-1 and Bacillus subtilis BT-2.