Optimization of lactic acid production by Lactobacillus delbrueckii through response surface methodology

This article describes the optimization through response surface methodology of a low-cost medium based on Corn Steep Liquor (CSL) for lactic acid production by Lactobacillu delbrueckii NRRL B445. The effect of the fermentation time was also considered. A maximum lactic acid concentration (93.4 g/L) was predicted using 15 g of CSL/L and 6 g of yeast extract/L at a fermentation time of 80.1 h. However, the maximum productivity (3.50 g/L/h) was predicted by using 15 g of CSL/L, 6 g of yeast extract/L, and 8.9 g of peptone/L after 24 h. From an economical perspective, better results were obtained using 15 g of CSL/L alone and 24 h, achieving a maximum economical productivity of 229.7 g of lactic acid per hour and considerable savings in nutrients.