Fermentative production of intracellular β-galactosidase by Bacillus safensis (JUCHE 1) growing on lactose and glucose-Modeling and experimental

Bacillus safensis (JUCHE 1) is an isolated bacterial strain which is capable to produce lactose hydrolyzing enzyme, β-galactosidase through fermentative route. Therefore, to enhance the production of β-galactosidase, systematic and programmed investigations are prerequisite. Unfortunately no attempt has yet been made to develop the mathematical model of B. safensis (JUCHE 1) growing on dual carbohydrate sources. In the present investigation a non-segregated structured model for B. safensis (JUCHE 1), growing in a medium containing multiple carbohydrate sources, namely, lactose and glucose has been developed. In the microbial growth medium lactose to glucose ratio has been varied from 3:1 to 39:1, and the total concentration of carbohydrate has been kept at 20 g L−1. The deterministic structured model, so developed, has been utilized to predict the concentration time histories of biomass generation, glucose, and lactose in the abiotic phase as well as the intracellular concentrations of lactose, lactose-6p, glucose-6p, β-galactosidase, and phospho-β-galactosidase through a combination of experimental, and computational studies. The model parameters were either evaluated through non-linear regression analysis of data obtained from programmed batch experiments in Erlenmeyer flasks with high correlation coefficient, or in some cases obtained from the literature. The model has been validated by comparison with some of the experimental data obtained from a large scale (5 L) bioreactor. It is expected that the developed model could be effectively used to predict the behavior of bioreactors, optimal operating conditions for enzyme production using B. safensis (JUCHE 1).