Response Surface Optimization of Critical Medium Components for the Production of Lactic Acid by Rhizopus arrhizus

Response surface methodology (RSM) was used to optimize fermentation medium for enhancing lactic acid production by Rhizopus arrhizus (RA). In the first step of optimization with Plackett- Burman design, in the second step, a 2 3 full factorial central composite design and RSM were applied to determine the optimal concentration of each significant variable. Three most effective medium constituents identified by initial screening method of Plackett- Burman were glucose, urea, and MgSO4. Central composite design (CCD) and Response Surface Methodology (RSM) were used in the design of the experiment and in the analysis of results. This procedure limited the number of actual experiments performed while allowing for possible interactions between the three components. The optimum values for the tested variables for the maximum lactic acid production were glucose 10.97g/lit urea 0.135g/lit and MgSO4 7.22%. The maximum lactic acid production was 182.5g/lit. It was 65.7g/lit increased from basal medium.