Cloning of the promoter region of the Trehalose-6-phosphate synthase gene TPS1 of the self-flocculating yeast and exploration of the promoter activity on ethanol stress

Abstract:

Improving stress tolerance of the microbial producers is of great importance for the process economy and efficiency of bioenergy production. Key genes influencing ethanol tolerance of brewing yeast can be revealed by studies on the molecular mechanisms which can lead to the further metabolic engineering manipulations for the improvement of ethanol tolerance and ethanol productivity. Trahalose shows protective effect on the cell viability of yeast against multiple environmental stress factors, however, further research is needed for the exploration of the underlying molecular mechanisms. In this study, the promoter region of the trehalose-6-phosphate synthase gene TPS1 was cloned from the self-flocculating yeast Saccharomyces cerevisiae flo, and a reporter plasmid based on the expression vector pYES2.0 on which the green fluorescence protein EGFP was directed by the TPS1 promoter was constructed and transformed to industrial yeast strain Saccharomyces cerevisiae ATCC4126. Analysis of the EGFP expression of the yeast transformants in presence of 7% and 10% ethanol revealed that the PTPS1 activity was strongly induced by 7% ethanol, showing specific response to ethanol stress. The results of this study indicate that trehalose biosynthesis in self-flocculating yeast is a protective response against ethanol stress.

Key words:self-flocculating yeast, trehalose-6-phosphate synthase, green fluorescence protein, report vector, ethanol stress