Biosurfactants (BS) are secondary metabolites produced by microorganisms, being able to reduce surface and interfacial tensions. It is important to reduce the cost of fermentation media, which represents about 50% of the final cost of the product. Therefore, agro-industrial, industrial and domestic residues have been proposed as substrates, as well as the use of yeasts, since most of them are generally recognized as safe (GRAS) and have a high substrate conversion rate. This study aimed to evaluate the antibacterial activity of the BS produced by the yeast Wickerhamomyces anomalus using kitchen waste oil (KWO) as substrate. The BS was produced in a bioreactor for 12h and purified through an adsorption column followed by medium performance liquid chromatography (MPLC). Antibacterial activity was performed by determining the Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC). The evaluated bacteria were Bacillus cereus, Escherichia coli, and Salmonella Typhimurium. B. cereus showed total inhibition at 120 µg/mL and total bactericidal activity at 480 µg/mL of crude biosurfactant. The crude BS evaluated against E. coli showed complete inhibition at 480 µg/mL but did not show bactericidal activity. The crude BS did not show inhibitory or bactericidal activity for S. Typhimurium. The purified BS was analyzed against the same bacteria to determine whether the antibacterial activity would come from the set of fractions or if it would be more effective purified. The purified BS was shown to be the most effective, showing inhibitory and bactericidal activities against B. cereus at 60 µg/mL MIC and MBC. The purified BS showed inhibitory activity at 240 µg/mL for E. coli and 480 µg/mL for S. Typhimurium, however, the BS fraction also did not show bactericidal activity against these two bacteria. The antimicrobial activity proved that the isolated and purified compound is more effective than the partially purified compound.

Ami Rose

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