Characterization of biosurfactants produced by Halobacillus dabanensis and Pontibacillus chungwhensi isolated from oil-contaminated mangrove ecosystem in Egypt

Abstract

The production and properties of biosurfactants synthesized by Halobacillus dabanensis and Pontibacillus chungwhensi, isolated from oil-contaminated mangrove sediments of Avicennia marina, Red Sea (Egypt) have been investigated. The two strains were classified as moderate halophile and halotolerant, respectively. The produced biosurfactants were considered as metabolites associated with the growth of H. dabanensis and P. chungwhensi and were able to reduce the interfacial tension to 20 and 19 mN/m, respectively. The partially purified biosurfactants showed high emulsiflcation value (E24) against n-hexadecane (68 and 72%, respectively). Biological degradation of n-alkane mixture and linear alkyl benzene after incubation of bacteria in Buslinell-Haas medium in presence and absence of the partially purified biosurfactants has been monitored. H. dabanensis and P. chungwhensi were capable of degrading 92. 3 and 94. 7% of n- alkane mixture and 76. 5 and 76. 7% of linear alkyl benzene, respectively. The biodegradation of n-alkane, achieved in the presence of biosurfactants was better than its degradation in control. The structural analysis of the biosurfactants proved them to be lipopeptides. Biosurfactant-producing halophilic/halotolerant microorganisms may play a significant role in accelerating remediation of oil-polluted saline environments. © 2013 Pleiades Publishing, Ltd.