Statistical optimization of critical medium components for biosurfactant production by Bacillus subtilis

Abstract

In the present study optimization of the critical medium components for biosurfactant production by Bacillus subtilis using statistical experimental design was studied. Response surface methodology (RSM) was employed to determine the optimal level of the four medium variables (sucrose, yeast extract, FeSO47H2O and KH2PO4). Central composite design (CCD) of RSM was applied to study the four variables at five levels and biosurfactant concentration was measured as response. Regression coefficients were calculated by regression analysis and the model equation was determined. R2 value for biosurfactant (g/L) was calculated as 0.835 and it indicates that the model was well fitted with the experimental results. Surface plots were made and the maximum biosurfactant production (10 g/L) was predicted at the optimized values of sucrose 70 g/L, yeast extract 5 g/L, FeSO47H2O 0.055 g/L and KH2PO4 0.15 g/L. The obtained mathematical model was verified by performing the experiment with the predicted optimized values and the yield of bio-surfactant was found to be 9.78 g/L. Validation of the predicted model was fitted 97.8% with the experimental results conducted at the optimum conditions. Results of this statistical analysis showed that sucrose and yeast extract had found significant medium components for biosurfactant production.

Keywords

• Bacillus subtilis
• biosurfactant
• central composite design
• response surface methodology