Optimization of Lipopeptide Biosurfactant Production by Bacillus clausii J1G0B and Its Application in Ex-situ Microbial Enhanced Oil Recovery (MEOR)
Abstract
The decline in global oil production has increased interest in microbial enhanced oil recovery (MEOR) using biosurfactant-producing microorganisms to improve oil mobilization. This study investigates Bacillus clausii J1G0B, a halophilic bacterium from Indonesian salt ponds, for optimized lipopeptide biosurfactant production and ex-situ MEOR application. Production conditions were optimized by varying carbon and nitrogen sources, identifying 2% palm oil and 15 mM urea as optimal for biosurfactant synthesis. The produced biosurfactant exhibited strong emulsification activity, achieving EI24 values of 94.70 ± 0.81% for palm oil and 80.00 ± 1.15% for crude oil. Biosurfactant produced in tryptone-supplemented medium (BS1) showed higher emulsification performance than that produced in urea medium (BS2), reaching up to 95.00 ± 1.15% toward palm oil. FTIR analysis confirmed the lipopeptide structure of the biosurfactant, while stability tests showed an initial decrease in the soluble fraction within 24 h, followed by relatively stable behavior up to 72 h. In ex-situ oil-washing assays, the biosurfactant achieved 67.70 ± 1.64% oil removal at 20,000 ppm. These results highlight the complementary roles of emulsification and oil washing and support the feasibility of crude production process from inexpensive substrates for cost-effective, sustainable ex-situ MEOR.