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 Lactobacilli: bulgaricus, casei, lactis, delbrueckii and fermentum were investigated. Cell growth and substrate utilization in a batch submerged culture of whey with added lactose were evaluated. Fitness assessment of experimental data on the cell growth and lactose consumption by Monod and Logistic kinetic models was performed using the curve-fitting tool in Matlab software. Lactobacillus delbrueckii subsp. bulgaricus PTCC1737 and Lactobacillus delbrueckii subsp. lactis PTCC 1743 didn’t fit with any of the two studied kinetic models. Lactobacillus casei subsp. casei PTCC1608 showed good consistency with Monod and not acceptable fitting with Logistic kinetic model. Lactobacillus delbrueckii subsp. delbrueckii PTCC1333 and Lactobacillus fermentum PTCC1744 had acceptable consistency with both studied models. Lactobacillus casei subsp. casei PTCC1608 showed the most consistency following Monod equation with R2, μmax and Ks of 0.965, 0.435 h-1 and 27.05 g L-1, respectively. Lactobacillus delbrueckii subsp. delbrueckii PTCC1333 (R2=0.926) had the most desired capability with Logistic equation with μmax and Xmax evaluated as 0.242 h-1 and 4.84 g L-1, respectively.