A comparative study of biosurfactant preparation by Pseudomonas aeruginosa MTCC 424 using rice bran oil and soybean oil substrates

Researchers world over are trying to find the low cost feed stocks for cost-effective production of biosurfactants in order to compete with the chemically synthesized traditional surfactants. In this study rhamnolipid biosurfactant was prepared by Pseudomonas aeruginosa MTCC 424 culture. The rice bran oil and soybean oil were the two substrates taken in the study, which were extracted from spent bleaching earth for use as low cost carbon source. Spent bleaching earth is a waste of vegetable oil processing industries and is usually disposed of in the landfills or waste dumps. Pseudomonas aeruginosa culture was preferred over other microorganisms due to its nutritional and biochemical versatility along with simple culture conditions. The two biosurfactants were screened using oil displacement, drop-collapse, cetyltrimethyl ammonium bromide agar plate, emulsification index and surface tension measurement tests. The chemical structure and composition were analyzed by Fourier transform infrared, nuclear magnetic resonance and thin layer chromatography spectroscopic test methods. The study proved residual rice bran oil based rhamnolipid biosurfactant as the better one compared to residual soybean oil based biosurfactant. Since the residual rice bran oil extracted from spent bleaching earth is a very cheap raw material, the present study is hoped to contribute to some extent in solving the issue of high production cost of biosurfactants.