జర్నల్ ఆఫ్ మైక్రోబియల్ & బయోకెమికల్ టెక్నాలజీ

నైరూప్య

L(+) Lactic Acid Production by New Lactobacillus Rhamnosus B 103

Cristian J. B. de Lima, Luciana F. Coelho, Gervásio P. Da Silva, Georgina L. M. Alvarez and J. Contiero

L(+) Lactic acid fermentation was studied by Lactobacillus rhamnosus sp. under the effects of pH control and a lowcost nutritional medium (sugarcane juice and corn steep liquor-CSL). Central composite design (CCD) was employed to determine maximum lactic acid production at optimum values for process variables and a satisfactory fi t model was realized. Statistical analysis of the results showed that the linear and quadratic terms of two variables (sugarcane juice and pH) had signifi cant effects. The interactions between the three variables were found to contribute to the response at a signifi cant level. A second-order polynomial regression model estimated that the maximum lactic acid production of 86.36 g/L was obtained when the optimum values of sucrose, CSL and pH were 112.65 g/L, 29.88 g/L and 6.2, respectively. Verifi cation of the optimization showed that L(+) lactic acid production was of 85.06 g/L. Under these conditions, Y_P/S and Q_P values of 0.85 g/g and 1.77 g/Lh, respectively, were obtained after 48 h fermentation, with a maximal productivity of 2.2 g/L h at 30 h of process.