Modeling and optimization of main factors in rhamno lipid production process by Pseudomonas aeruginosa hr

Abstract

Producing bacterium of rhamnolipid in this research is, P. aeruginosa HR was isolated from Iranian oil wells. First, the effect of three factors pH (6.5-7.5), Temperature (30-35˚C), and Carbon/Nitrogen ratio (C/N) (24-32) on biosurfactant production were investigated using Taguchi model. Lindhard medium which is known as the best culture medium in laboratory scale was used and optimum condition (pH = 7.5, T = 33˚C, C/N ratio = 24) was determined. Then, under the obtained optimum condition, in semi-pilot scale (fermenter), the effect of three important factors, C/N ratio (14-24), stirrer rate (100-400 rpm), and aeration rate (0.5-2 Vvm) was evaluated using Taguchi model. The optimum condition was as follows: C/N ratio = 18, stirrer rate = 100 rpm, aeration rate = 1.5 Vvm. Finally, the experimental data for laboratory and fermenter scales were compared with estimated values according to a mathematical model for the production of biosurfactants at this research from P. aeruginosa . The appropriate polynomial expansions that coincide with these data were obtained by exponential method.