Screening the antimicrobial activity of biosurfactants produced by microorganisms isolated from refinery wastewaters

Abstract

In this study, isolation and identification of microorganisms from petroleum refinery wastewater with biosurfactant producing ability and characterization of biosurfactants were investigated. Biosurfactant production ability of microorganisms isolated from wastewater was determined by drop collapse method. The initial characterization of biosurfactants was investigated by biochemical tests and FTIR analysis. Biosurfactants were investigated for potential antimicrobial activity as inhibition zone, minimum inhibitory concentration, and minimum bactericidal concentration against medically important bacterial strains. We found that the biosurfactants showed profoundly distinct antimicrobial activity toward test organisms. Maximum antibacterial activity was shown by BS-III against K. pneomoniae followed by BS-IV against E.coli. Also biosurfactants displayed a antifungal activity against tested yeasts with the diameters of zone inhibition ranging between 12 and 17 mm. The maximum antifungal activity was obtained with BS-III against C. krusei. The MIC values obtained in this study were lower than the MBC values for all tested biosurfactants. Maximum MBC values were recorded with E. coli and were 64mg/ml for BS-I. The main commercial use of biosurfactants is oil industry, foods and environmental technology because of their ability to stabilize emulsions. The antimicrobial activity of biosurfactants has not been reviewed extensively. From preliminary characterization results it can be said that biosurfactants are a suitable alternative in potential applications of medical fields.