Structured modeling of a microbial system: III. Growth on mixed substrates.

A two-compartment model is extended to describe growth and product formation on a mixture of different carbohydrate sources. The open-ended structure of the compartment model is utilized to include description of the basic mechanisms of catabolite repression. The model is used to simulate batch triauxic, steady-state, and transient fermentation, and the simulations are compared with experimental results obtained with growth of the lactic acid bacteria Streptococcus cremoris on mixtures of glucose, galactose, and lactose. The model adequately describes characteristic experimental observations such as substrate preference and carbohydrate adoption.