Abstract:The response surface methodology was employed to optimize the culture medium and conditions of Pseudomonas aeruginosa for enhanced production of rhamnolipids,and the produced rhamnolipids before and after optimization were characterized.The factors studied included concentrations of carbon,nitrogen,and phosphorus sources,initial pH,rotating speed,and inoculum percentage.The significant factors affecting the concentration of rhamnolipids—identified through Plackett-Burman design—were nitrogen source concentration,rotating speed,and inoculum percentage.On the basis of these findings,Box-Behnken response surface experiments determined the optimal conditions as nitrogen source concentration of 4.74 g/L,inoculum percentage of 6.22%,and rotating speed of 203.76 r/min,under which the concentration of rhamnolipids reached 23.70 g/L.Furthermore,the products were purified and characterized,and the critical micelle concentration and emulsifying ability of rhamnolipids were determined.The results indicated that rhamnolipids produced by the unoptimized medium with glycerol as the carbon source exhibited higher surface activity,whereas rhamnolipids produced by the optimized medium with soybean oil as the carbon source showed superior emulsifying ability.