Biosurfactant production by Bacillus subtilis TD4 and Pseudomonas aeruginosa SU7 grown on crude glycerol obtained from biodiesel production plant as sole carbon source

This study presents isolation of biosurfactant (BS)-producing bacteria, Bacillus subtilis TD4 (BsTD4) and Pseudomonas aeruginosa SU7 (PaSU7), from palm oil contaminated soil. BS production was done by using a minimal salt medium with used crude glycerol as carbon and commercial monosodium glutamate as nitrogen source. After microbial cultivations at 30 degrees C under optimum conditions, BSs produced by BsTD4 and PaSU7 reduced surface tension of culture supernatant to 30 mN/m with BS yield of 2.65 and 2.25 g/l, respectively. BSs could reduce surface tension of pure water to 26.0 and 28.0 mN/m with critical micelle concentration (CMC) of 12 mg/l (BsTD4) and 20 mg/l (PaSU7). BS produced by BsTD4 exhibited higher oil recovery efficiency than that produced by PaSU7. Both BSs could recover oil more effectively than synthetic surfactants, could enhance solubility of PAHs, and can emulsify various oil and hydrophobic compounds.