Utilization of spent wash for optimum production of biosurfactant using response surface methodology

The production of a biosurfactant by Bacillus subtilis MTCC 1427 was investigated using Design of Experiments software. The Central Composite Design (CCD) - Response surface methodology (RSM) was applied to understand the interactive effects of 16 experiments carried out for 100 hours in submerged fermentation for the production of biosurfactant. Further, the effect of 3 variables, i.e. pH, substrate concentration (spent wash) and inoculums volume on the biosurfactant activity was investigated. The optimum conditions of the variables were determined and found to be pH 6.0034, spent wash concentration 20.0341 % and inoculum volume of 7.0869 ml. The p 0.05 indicated that model was significant. Regression coefficient R2 of 0.9821 indicated excellent evaluation of experimental data by second order polynomial regression model. Applying RSM, the surface tension could be reduced from 72 mN/m to 29.436 mN/m, suggesting that the RSM to be an ideal tool for optimization of fermentation parameters in the production of biosurfactant. This study revealed that the exclusive utilization of spent wash without supplement with a refi8ned nutrient source is feasible and could ensure the economic sustainability of biosurfactant production.