Functional characterization of a biosurfactant-producing thermo-tolerant bacteria isolated from an oil reservoir

A Bacillus subtilis strain JA-1 isolated from an oil reservoir was studied. This strain is capable of growth and producing biosurfactant at a temperature of 60 ℃. In nutrient medium it produced biosurfactant which reduced the surface tension from 68.2 mN/m to 28.3 mN/m, with the critical micelle concentration （CMC） of 48 mg/L. The measured surface tension indicated that the biosurfactant possessed stable surface activity at high temperature and a specific range of pH and salt concentrations. The results of thin layer chromatography （TLC） together with FT-IR showed that the metabolic product of strain JA-1 is a lipopeptide biosurfactant. The ability to growth at high temperature and to produce biosurfactant makes strain JA-1 promising for enhanced oil recovery.