The influence of nitrate on the physiology of the yeast Dekkera bruxellensis grown under oxygen limitation.

A previous study showed that the use of nitrate by Dekkera bruxellensis might be an advantageous trait when ammonium is limited in sugarcane substrate for ethanol fermentation. The aim of the present work was to evaluate the influence of nitrate on the yeast physiology during cell growth in different carbon sources under oxygen limitation. If nitrate was the sole source of nitrogen, D. bruxellensis cells presented slower growth, diminished sugar consumption and growth-associated ethanol production, when compared to ammonium. These results were corroborated by the increased expression of genes involved in the pentose phosphate (PP) pathway, the tricarboxylic acid (TCA) cycle and ATP synthesis. The presence of ammonium in the mixed medium restored most parameters to the standard conditions. This work may open up a line of investigation to establish the connection between nitrate assimilation and energetic metabolism in D. bruxellensis and their influence on its fermentative capacity in oxygen-limited or oxygen-depleted conditions.