Growth kinetic models of five species of Lactobacilli and lactose consumption in batch submerged culture.

Kinetic behaviors of five Lactobacillus strains were investigated with Contois and Exponential models. Awareness of kinetic behavior of microorganisms is essential for their industrial process design and scale up. The consistency of experimental data was evaluated using Excel software. L. bulgaricus was introduced as the most efficient strain with the highest biomass and lactic acid yield of 0.119 and 0.602gg(-1) consumed lactose, respectively. The biomass and carbohydrate yield of L. fermentum and L. lactis were slightly less and close to L. bulgaricus. Biomass and lactic acid production yield of 0.117 and 0.358 for L. fermentum and 0.114 and 0.437gg(-1) for L.actobacillus lactis were obtained. L. casei and L. delbrueckii had the less biomass yield, nearly 11.8 and 22.7% less than L. bulgaricus, respectively. L. bulgaricus (R(2)=0.9500 and 0.9156) and L. casei (R(2)=0.9552 and 0.8401) showed acceptable consistency with both models. The investigation revealed that the above mentioned models are not suitable to describe the kinetic behavior of L. fermentum (R(2)=0.9367 and 0.6991), L. delbrueckii (R(2)=0.9493 and 0.7724) and L. lactis (R(2)=0.8730 and 0.6451). Contois rate equation is a suitable model to describe the kinetic of Lactobacilli. Specific cell growth rate for L. bulgaricus, L. casei, L. fermentum, L. delbrueckii and L. lactis with Contois model in order 3.2, 3.9, 67.6, 10.4 and 9.8-fold of Exponential model.