Biosurfactant production by Pseudomonas aeruginosa SP4 using sequencing batch reactors: Effect of oil-to-glucose ratio

Sequencing batch reactors were used for biosurfactant production from Pseudomonas aeruginosa SP4. The lab-scale aerobic sequencing batch reactor units were operated at an oil loading rate of 2 kg/m(3) day, a cycle time of 2 days/cycle, and a temperature of 37 degrees C. A mineral medium with palm oil was used as the culture medium. Glucose, a supplemental carbon source, was added for enhancing the microbial growth, which, in turn, gave a better process stability. The optimum oil-to-glucose ratio for the biosurfactant production was 40:1, providing a surface tension reduction of 58.5%, a chemical oxygen demand removal of 85.1%, and an oil removal of 77.7%. The maximum biosurfactant concentration in the bioreactors was about 1.1 times the critical micelle concentration. The biosurfactant product was predominantly composed of Rha-Rha-C-8-C-10 and Rha-Rha-C-10-C-8, and its critical micelle concentration was 150 mg/l. (C) 2009 Elsevier B.V. All rights reserved.