Quantitative assessment of DNA damage in the industrial ethanol production strain Saccharomyces cerevisiae PE-2

Abstract

Lignocellulosic hydrolysates remain one of the most abundant substrates for the sustainable production of second generation fuels and chemicals with Saccharomyces cerevisiae. Fermentation inhibitors such as acetic acid, furfural and hydroxymethylfurfural are formed in varying amounts depending of the hydrolysis conditions which cause slow or stuck fermentations, a topic that has garnered much research. Some fermentation inhibitors such as furfural are also genotoxic agents that can cause genetic instability of the production strain. We present a novel dominant DEL cassette (dDEL) by which DNA damage can be quantified in wild-type or industrial yeast strains. The ethanol production strain S. cerevisiae PE-2 was more resistant to 4 mM hydrogen peroxide (H2O2) for 5-20 min or up to 20 mM furfural for 17 h compared to the laboratory DEL strain RS112. The PE-2 showed a low tendency for recombination consistent with efficient DNA protection compared to the laboratory strain. Measuring genetic stability quantitatively with the dDEL assay could aid in the selection of robust yeast strains or processes strategies using second generation raw materials.