Production of novel rhamnolipids via biodegradation of waste cooking oil using Pseudomonas aeruginosa MTCC7815

In this paper, Pseudomonas aeruginosa MTCC7815, a biosurfactant producing strain was studied for its ability to utilize waste cooking oil (WCO) as a sole carbon source for the production of biosurfactant. Culture conditions were optimized based on surface tension reduction and biomass concentration. The obtained biosurfactant was characterized using H-1 NMR, FTIR, LC-MS, and MALDI-TOF techniques. The chemical properties of the produced biosurfactant were estimated by assessing the critical micelle concentration (CMC), emulsification index (E-24) and oil displacement test. The optimal culture conditions were found to be similar to the natural domestic sewage such as basic pH value of 10, temperature of 25 degrees C and a very high WCO concentration of 40 gL(-1) (C/N ratio of 40/1). The biosurfactant yield was found to be significant as 11 +/- 0.2 gL(-1) upon utilizing about 90% of WCO within 5days of incubation. The biosurfactant produced was found to be a mixture of mono- and di-rhamnolipid in nature and comprised excellent surface active properties i.e. an extremely low CMC of 8.8 +/- 0.3 mgL(-1), E-24 of 62.5 +/- 0.3% and surface tension reduction up to 26.2 +/- 0.5 mNm(-1). These results suggest the suitability of Pseudomonas aeruginosa for the biosurfactant production at commercial scale along with waste remediation in an economic way.