Effect and application of proline metabolism-related gene CgMCUR1 on stress tolerance of Candida glycerinogenes and Saccharomyces cerevisiae

AIMS: To investigate the effect of CgMCUR1 on the phenotype of Candida glycerinogenes and Saccharomyces cerevisiae. METHODS AND RESULTS: Inhibition of CgMCUR1 expression reduced acetate, H2O2, and high temperature tolerance of C. glycerinogenes. Expression of CgMCUR1 resulted in better acetic acid, H2O2, and high temperature tolerance in recombinant S. cerevisiae. Meanwhile, CgMCUR1 was able to enhance intracellular proline accumulation. The qRT-PCR analysis revealed that overexpression of CgMCUR1 affected proline metabolism in recombinant S. cerevisiae. The overexpression strain also showed reduced levels of cellular lipid peroxidation and an altered ratio of saturated fatty acid (SFA) to unsaturated fatty acid (UFA) in the cell membrane. The ethanol production of recombinant S. cerevisiae at high temperature was 30.9 g l-1, obtaining an increase of 12%, and the conversion rate was increased by 12%. In the undetoxified cellulose hydrolysate, the ethanol yield was 14.7 g l-1 at 30 h with an improvement of 18.5%, and the conversion rate was increased by 15.3%. CONCLUSIONS: Overexpression of CgMCUR1 rendered the acetic acid, H2O2, and high temperature tolerant of recombinant S. cerevisiae and enhanced the ethanol fermentation performance of recombinant S. cerevisiae under high temperature stress and in undetoxified cellulose hydrolysate by improving intracellular proline accumulation and by changing cellular physiological metabolism.