Utilization of Oil Industry Residues for the Production of Rhamnolipids by Pseudomonas indica

In the present work, a new strain Pseudomonas indica MTCC 3714 was studied for the production of biosurfactants using various rice‐bran oil industry residues viz. rice‐bran, de‐oiled rice‐bran, fatty acids and waxes. Among all the carbon sources, a maximum reduction in surface tension (26.4 mN/m) was observed when the media were supplemented with rice‐bran and the biosurfactant was recovered using the ultrasonication technique as one of the steps in the extraction process. Biosurfactants were obtained in yields of about 9.6 g/L using rice‐bran as the carbon source. The structure of the biosurfactants as characterized by FT‐IR, NMR (1H and 13C) and LC–MS analysis revealed that the majority of the biosurfactants were di‐rhamnolipids. The biosurfactants produced were able to emulsify various hydrocarbons and showed excellent potential in microbial enhanced oil recovery, as it was able to recover kerosene up to 70 % in a sandpack test.