Fermentative production of rhamnolipid and purification by adsorption chromatography.

Glycolipids are one of the major classes of biosurfactants in which the rhamnolipids are best studied. The present work investigates the optimization of inoculum age and batch time for maximizing the yield of rhamnolipid from Pseudomonas aeruginosa (MTCC 2453). The yield and titer of rhamnolipids were maximum in the fermentation batch with an inoculum age of 24 hr. Batch time studies were performed on biomass production, rhamnolipid production, and sunflower oil utilization. The maximum yield of rhamnolipid was achieved at 96 hr when the culture cells were in the late exponential/early stationary phase. At optimum substrate concentration, maximum yield of 10.8 g/L was achieved. Further, downstream processing of crude rhamnolipid from broth using organic solvent extraction and subsequent purification using adsorption chromatography was done. In this study, chromatographic method was developed for purification of rhamnolipid by adsorption phenomena with more than 88.7% purity and 86.5% recovery. The present study provides new perspective on concepts involving separation by adsorption. Further antimicrobial properties and surfactant properties were studied for rhamnolipid production.