Transcriptome of the Alternative Ethanol Production Strain Dekkera bruxellensis CBS 11270 in Sugar Limited, Low Oxygen Cultivation

Dekkera bruxellensis can outcompete Saccharomyces cerevisiae in environments with low sugar concentrations. It is usually regarded as a spoilage yeast but has lately been identified as an alternative ethanol production organism. In this study, global gene expression in the industrial isolate D. bruxellensis CBS 11270 under oxygen and glucose limitation was investigated by whole transcriptome sequencing using the AB SOLiD technology. Among other observations, we noted expression of respiratory complex I NADH-ubiquinone reductase although D. bruxellensis is a Crabtree positive yeast. The observed higher expression of NADH-generating enzymes compared to NAD(+)-generating enzymes might be the reason for the previously observed NADH imbalance and resulting Custer effect in D. bruxellensis. Low expression of genes involved in glycerol production is probably the molecular basis for high efficiency of D. bruxellensis metabolism under nutrient limitation. No D. bruxellensis homologs to the genes involved in the final reactions of glycerol biosynthesis were detected. A high number of expressed sugar transporter genes is consistent with the hypothesis that the competitiveness of D. bruxellensis is due to a higher affinity for the limiting substrate.