Molasses as a whole medium for biosurfactants production by Bacillus strains and their application.

ABSTRACT

Two types of biosurfactant (BS)-producing bacteria, Bacillus licheniformis TR7 and Bacillus subtilis SA9, were isolated from mangrove sediment in the south of Thailand. The BS production was done by using only molasses as a whole medium for growth and production. Under optimized conditions, the yields of TR7 and SA9 BS were found to be 3.30 and 3.78 g/l, respectively. It could reduce the surface tension of pure water to 28.5 and 29.5 mN/m, with the critical micelle concentrations of about 10 and 30 mg/l, respectively. Good thermal, pH, and salt stability were exhibited. Both BSs could recover oil more effectively than the two synthetic surfactants. In addition, TR7 and SA9 BS could enhance the solubility of polyaromatic hydrocarbons (PAHs). Thus, these BSs have the potential for the removal of oil and PAHs from the combined contaminated environment and facilitate its bioremediation. These studies indicate that molasses, as a renewable, relatively inexpensive and easily available resource, can be used for important biotechnological processes.