Production of Lactobacillus Cells by Dialysis Continuous Fermentation of Deproteinized Whey

A mathematical model was used to simulate the continuous conversion of deproteinized whey into bacterial cells by a process in which the fermentor contents are poised at a constant pH by the addition of ammonia and are dialyzed through a membrane against water. The simulations predicted outcomes and parameters for experimental tests. Dried deproteinized cheese whey was rehydrated with tap water to high concentration (242 mg lactose/ml), supplemented with yeast extract (8 mg/ml), charged into a 5-liter fermentor without sterilization, adjusted in pH (5.5) and temperature (44 C), and inoculated with an adapted culture of Lactobacillus bulgaricus. A series of steady-state conditions was managed for 71 days without sterilization or asepsis. Cell concentration, cell productivity, and substrate conversion were more than twice those from an ordinary continuous fermentation for production of Lactobaeillus cells.