Antibacterial effects of the biosurfactant produced by Sporisorium sp. aff. sorghi SAM۲۰

BACKGROUND AND OBJECTIVESBiosurfactants are amphiphilic compounds that are mainly produced by microorganisms. Mannosylerythritol lipids (MELs), which are glycolipid biosurfactants produced by some yeast strains, show not only excellent interfacial properties but also versatile biological activity. The yeast Sporisorium sp. aff. sorghi SAM۲۰ was previously identified as a producer of unique pattern of MEL mixtures. This study aimed to investigate the antibacterial activity of the biosurfactant mixture against some reference bacteria.MATERIALS AND METHODSThe strain was cultured in a medium containing ۴% corn oil as carbon source at ۲۸ °C for ۷ days. The surface activity of the broth was confirmed by oil displacement assay. The biosurfactants were recovered and partially purified by ethyl acetate and then methanol-hexane extraction. The antibacterial activity of the biosurfactant mixture was determined at different concentrations from ۰ to ۲۰۰۰ mg/l by broth microdilution method according to CLSI (Clinical and Laboratory Standard Institute) guidelines and the growth inhibition percentages were calculated.RESULTS AND DISCUSSIONThe biosurfactant mixture did not completely inhibit the bacterial growth at the applied concentrations. Bacillus cereus ATCC ۱۱۷۷۸ was the most sensitive bacterium to the biosurfactant with ۷۳-۹۸% growth inhibition in the selected concentrations. The growth inhibition range of Staphylococcus aureus subsp. aureus ATCC ۳۳۵۹۱ was ۳۸-۸۱%, while the inhibition of Escherichia coli ATCC ۸۷۳۹, Pseudomonas aeruginosa ATCC ۱۰۱۴۵, and Salmonella enterica subsp. enterica ATCC ۱۳۰۷۶ were <۵۰% in different concentrations.CONCLUSIONThe biosurfactant mixture produced by Sporisorium sp. aff. sorghi SAM۲۰ showed antimicrobial effects particularly against Gram-positive bacteria. According to the results, the biosurfactants may have potential application as a preservative in food and cosmetic products.

کلیدواژه ها:

Antibacterial effect ، Biosurfactant ، Mannosylerythritol lipids ، Sporisorium