ABSTRACT
In the present study lactic acid production was enhanced by optimizing the three process variables viz; inoculum size, temperature and pH using three factor five level CCRD [central composite rotatable design] by Lactobacillus delbruckii under SMF [submerged fermentation process]. Paneer [dairy byproduct] whey was used as sole substrate for lactic acid production. Design Expert 8.0.2.0 software depicted that an optimum concentration of 8% [v/v] size of inoculum, 5.50 pH and 36.53°C temperature gave lactic acid and biomass yield of 5.61 g/L[-1] and 4.27 g/L[-1], respectively. Lactic acid production was scale up in 7.5 L bioreactor under optimized conditions and it gave lactic acid and biomass yield of 39.2 +/- 1.4 and 47.6 +/- 0.8 g/L[-1], respectively. micro[g], Y[P/S], Y[P/X] and productivity were found to be 0.14 h[-1], 0.66 g/g, 0.7 g/g and 1.98 g/L[-1] h, respectively. Leudking Piret equation deduced that lactic acid production was growth associated which varies from earlier reports. Lactic acid was characterized by FTIR [Fourier transform infrared spectroscopy] and HPLC