[Objective] To improve thermal tolerance of Saccharomyces cerevisiae strains for efficient ethanol fermentation under high temperature. [Methods] Vacuolar proteinase B encoding gene PRB1 was integrated into the genome of S. cerevisiae, and cell growth and ethanol fermentation of the recombinant strain were compared with those of the control strain carrying the empty plasmid at 41 °C. [Results] PRB1 overexpressing strain consumed glucose completely in the fermentation broth within 31 h, whereas high residual glucose was detected in the fermentation broth of the control strain (35 g/L, about 40% of the total sugar amount) at 23 h and the glucose level was not changed until 31 h. [Conclusion] Overexpression of vacuolar protease B encoding gene improved yeast thermal tolerance and ethanol production under high temperature. The robust strain developed in this study has provided basis to further improve thermal tolerance and efficiency of high-temperature ethanol fermentation of the industrial strains and reduce the production cost of fuel ethanol.
