Probing control of glucose feeding in Vibrio cholerae cultivations

Infection with Vibrio cholerae is a significant problem in many developing countries. Cultivation of V. cholerae is used in production of cholera toxin B subunit, which is a component in a cholera vaccine. Fed-batch cultivations with V. cholerae in defined media have been conducted and reproducible results were obtained. A probing feeding strategy developed by Akesson for Escherichia coli cultivations has been tested. The strategy is working as well for V. cholerae as for E. coli in minimizing the amount of acetic acid formed and avoiding anaerobic conditions. At 2 h after the feed start most of the acetic acid accumulated during the batch phase is consumed. The resulting feed rate tends to be the highest possible with respect to the constraints from cell metabolism and mass transfer, thus maximizing productivity in terms of biomass. A cell dry weight of 20-23 g/l is obtained after 12 h of feeding.