A study on isolation, extraction, purification and characterization of surfactin by Bacillus subtilis from oil contaminated soilsAuthor(s): M.Chandran, M.Prabhakaran
Biosurfactants are microbial surface active agents produced by variety of microorganism and it has great potential advantages over chemical surfactant. Surfactin is a type of biosurfactant produced by Bacillus subtilis, its production kinetics under different conditions and their efficient activity are examined in this study. Oil contaminated soil samples were collected from petroleum industry in north Chennai, India and Bacillus subtilis is isolated for screening of surfactin production. The growth parameters such as size of the inoculum, period of inoculation, concentration of glucose substrate were optimized for better yield of surfactin. Thus the microbial synthesized surfactin is screened for surfactant activity by emulsification test, oil displacement test, drop collapsing test and chemically characterized by thin layer chromatography. The stability of the surfactin was determined by various parameters (temperature, pH and salinity). A better yield of 1.8g/l surfactin was obtained, when the glucose concentration of 40g/l were used along with 2% v/v size of inoculum at 72 hours of incubation. The surfactin activity was found to be high for diesel when compared to petrol. The chemical characterization of surfactin revealed red spots with retention factor of 0.53. The surfactin thus obtained was found to be thermo stable and active at the pH range of 7 to 9 and upto the salt concentration of 10% w/ v. Thus the surfactin obtained can be used in various industries including petroleum, food, pharmaceuticals, cosmetics etc.