Quantitative aerobic physiology of the yeast Dekkera bruxellensis , a major contaminant in bioethanol production plants

Abstract

Dekkera bruxellensis has been described as the major contaminant yeast of industrial ethanol production, although little is known about its physiology. The aim of this study was to investigate the growth of this yeast in diverse carbon sources and involved conducting shake flasks and glucose or sucrose-limited chemostats experiments, and from the chemostat data the stoichiometry of biomass formation during aerobic growth was established. As a result of the shake flask experiments with hexoses or disaccharides, the specific growth rates were calculated and a different behavior in rich and mineral medium was observed concerning to profile of acetate and ethanol production. In C-limited chemostats conditions, the metabolism of this yeast was completely respiratory and the biomass yields reached values of 0.62 gDW.gS(-1) . In addition, glucose pulses were applied to the glucose or sucrose-limited chemostats. These results showed that D. bruxellensis has a short-term Crabtree effect. While the glucose pulse was at the sucrose-limited chemostat, sucrose accumulated at the reactor, indicating the presence of a glucose repression mechanism in D. bruxellensis. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.