Improved ethanol fermentation by heterologous endoinulinase and inherent invertase from inulin by Saccharomyces cerevisiae.

It is hypothesized that introduction of an endoinulinase gene into Saccharomyces cerevisiae will improve its inulin utilization and ethanol fermentation through collaboration between the heterologous endoinulinase and the inherent invertase SUC2. The aim of this work was to test the hypothesis by introducing the endoinulinase gene inuA from Aspergillus niger into S. cerevisiae. The results showed that heterologous inuA expressed in S. cerevisiae selectively digested long chains of inulin into short fructooligosaccharides and parts of these fructooligosaccharides could be efficiently utilized by the yeast. This study demonstrated that collaboration between heterologous endoinulinase and inherent invertase improved inulin degradation and ethanol fermentation in S. cerevisiae.