BIOSURFACTANT PRODUCED BY NOVEL HALO-THERMOPHILIC BACTERIAL STRAIN FROM UNCONVENTIONAL SUBSTRATESAbstract
Our ecosystem is laden with hazardous and non-hazardous wastes that pose a serious threat to bio-existence. Most pharmaceutical formulations contain chemically-synthesized surfactants. The purpose of this work is to suggest an alternative source of surfactant which would also aid in ridding our environment of harmful wastes. Bacillus licheniformis B-4 strain isolated from a hydrocarbon dump site produces biosurfactant with excellent interfacial properties utilizing unconventional substrates (kerosene and diesel) as carbon sources, and glucose as an energy source. Acid precipitation and foam separation methods were used for biosurfactant recovery and its physicochemical properties evaluated which include the effect of the biosurfactant on the surface tension of water, critical micelle concentration (CMC), emulsification stability (ES) of kerosene and diesel, emulsification index, hemolytic activity, and antimicrobial activity. The results showed that the biosurfactant reduced the surface tension of water from 70.2 to 14.7 Nm-1, CMC was estimated to be 50 mg/l, emulsification stability of kerosene and diesel were obtained as 0.06 and 0.02 min-1, while the emulsification indices were 72.2 and 50 % respectively for kerosene and diesel. Hemolytic activity of the biosurfactant showed concentration-dependent lyses of blood cells while antimicrobial studies also showed concentration-dependent inhibition of bacterial cells. The results obtained from the analysis showed that the biosurfactant could serve as a good alternative to chemically-synthesized surfactants.
C. J. Igbonekwu, U. E. Osonwa, C. E. Umeyor*, M. N. Ikegbunam, E. M. Uronnachi and C. O. Esimone
Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmaceutical Sciences, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.
10 November 2013
14 December 2013
29 December 2013
01 January 2014