Evaluation of Cell Growth and Substrate Consumption Kinetic of Five Different Lactobacilli in a Submerged Batch Whey Culture for Lactic Acid Production

Cell growth and lactose consumption profile of five Lactobacillus Strains: bulgaricus, casei, lactis, delbrueckii and fermentum has been investigated. Experiments of cell growth and substrate utilization were conducted in batch submerged culture of whey with added lactose and some other growth factors. Fitness assessment of experimental data on the cell growth and lactose consumption by Monod kinetic model was performed using the curve-fitting tool in Mat Lab software. Lactobacillus casei subsp. casei PTCC1608 with R2, μmax and Ks as 0.965, 0.435 h-1 and 27.05 g L-1, respectively showed the most fitness with Monod equation. Between the investigated strains, Lactobacillus fermentum PTCC1744 also showed an acceptable consistency with Monod kinetic model (R2= 0.951). Its μmax and Ks values were 0.134 h-1 and 54.46 g L-1, respectively. Lactobacillus delbrueckii subsp. Bulgaricus PTCC1737 (R2= 0.891) and Lactobacillus delbrueckii subsp. lactis PTCC 1743 (R2=0.857) did not have an accepted fitness with Monod kinetic model.