Antibacterial activity of the biosurfactant produced by Starmerella bombicola SAM۱۹

BACKGROUND AND OBJECTIVESSophorolipids (SLs) are glycolipid biosurfactants produced by some yeast strains. They have gained a lot of attention in recent decades due to their unique functional and bioactive properties. Starmerella bombicola is the best-known SL producer. This study aimed to investigate the antibacterial activity of the biosurfactant produced by S. bombicola SAM۱۹, which previously isolated from the flower of Tragopogon dubius in Iran, against some reference bacteria.MATERIALS AND METHODSThe yeast strain was cultured in a medium containing ۱۰% glucose, ۴% corn oil, ۱% yeast extract, and ۰.۱% urea at ۲۸ °C for ۷ days. The surface activity of the broth was confirmed by oil displacement assay. The biosurfactant was recovered and partially purified by ethyl acetate and then methanol-hexane extraction. The antibacterial activity of the crude biosurfactant was determined at different concentrations from ۰ to ۱۰۰۰ mg/l by broth microdilution method according to CLSI (Clinical and Laboratory Standard Institute) guidelines and the percentages of growth inhibition were calculated.RESULTS AND DISCUSSIONThe MIC (Minimum inhibitory concentration) of the crude biosurfactant for Bacillus cereus ATCC ۱۱۷۷۸ was less than ۳۱.۲۵ mg/l, but the growth of other bacteria did not completely inhibit at the applied concentrations. The percentages of growth inhibition of Staphylococcus aureus subsp. aureus ATCC ۳۳۵۹۱, Salmonella enterica subsp. enterica ATCC ۱۳۰۷۶, Escherichia coli ATCC ۸۷۳۹, and Pseudomonas aeruginosa ATCC ۱۰۱۴۵ were ۶-۸۹%, ۵۵-۷۸%, ۲۵-۷۳% and ۶-۱۳%, respectively.CONCLUSIONAccording to the results, the biosurfactant produced by S. bombicola SAM۱۹ showed antibacterial effects and it may have potential application as partial or total substitutes for antibacterial agents and preservatives applied in a variety of commercial products.

کلیدواژه ها:

Antibacterial effect ، Biosurfactant ، Sophorolipids ، Starmerella