Bioremediation of crude oil contamination using microbial surface-active agents: isolation, production and characterization

Abstract

The present study highlights isolation, screening, production, characterization of marine microbial surface active agents followed by evaluating the efficacy of said surface -active agents for bioremediation of crude oil contamination. Upon screening, six potential surface-active agents producing isolates of Bacillus genera with significant difference in their morphology were obtained from marine sediments of Tamil Nadu coastal area. Results from optimization studies revealed, sucrose and yeast extract were the suitable carbon and nitrogen sources for growth, pH of 7.2 ± 0.2, temperature of 37°C and agitation at 180-200 rpm were the other optimized variables for the maximum production of surface-active agents irrespective of the bacterial isolates. Extraction and characterization studies reveals, the product was polymeric in nature with the surface activity in the range of 28 ± 4 mN/m. Thermal stability was comparable with that of synthetic surfactants and exhibit appreciable emulsifying activity and emulsion stability (more than 90 days). Laboratory scale studies on removal of crude oil from aqueous phase demonstrate, >90% of crude oil was removed within 60-120 minutes of exposure to the partially purifi ed surface-active agents. The percentage removal showed signifi cant difference for the six different surface-active agents.