Heterologous expression of Saccharomyces cerevisiae MPR1 gene confers tolerance to ethanol and L: -azetidine-2-carboxylic acid in Hansenula polymorpha.

Hansenula polymorpha is a naturally xylose-fermenting yeast; however, both its ethanol yield from xylose and ethanol resistance have to be improved before this organism can be used for industrial high-temperature simultaneous saccharification and fermentation of lignocellulosic materials. In the current research, we checked if the expression of the Saccharomyces cerevisiae MPR1 gene encoding N-acetyltransferase can increase the ethanol tolerance of H. polymorpha. The S. cerevisiae MPR1 gene was cloned in the H. polymorpha expression vector under the control of the H. polymorpha strong constitutive promoter of the glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH). H. polymorpha recombinant strains harboring 1-3 copies of the S. cerevisiae MPR1 gene showed enhanced tolerance to L: -azetidine-2-carboxylic acid and ethanol. The obtained results suggest that the expression of the S. cerevisiae MPR1 gene in H. polymorpha can be a useful approach in the construction of H. polymorpha strains with improved ethanol resistance.