Acetic acid- and furfural-based adaptive evolution of Saccharomyces cerevisiae strains for improving stress tolerance and lignocellulosic ethanol production

Abstract

Acetic acid and furfural are known as prevalent inhibitors deriving from pretreatment during lignocellulosic ethanol production. They negatively impact cell growth, glucose uptake and ethanol biosynthesis of Saccharomyces cerevisiae strains. Development of industrial S. cerevisiae strains with high tolerance towards these inhibitors is thus critical for efficient lignocellulosic ethanol production. In this study, the acetic acid or furfural tolerance of different S. cerevisiae strains could be significantly enhanced after adaptive evolution via serial cultivation for 40 generations under stress conditions. The acetic acid-based adaptive strain SPSC01-TA9 produced 30.5 g·L–1 ethanol with a yield of 0.46 g·g–1 in the presence of 9 g·L–1 acetic acid, while the acetic acid/furfural-based adaptive strain SPSC01-TAF94 produced more ethanol of 36.2 g·L–1 with increased yield up to 0. 49 g·g–1 in the presence of both 9 g·L–1 acetic acid and 4 g·L–1 furfural. Significant improvements were also observed during non-detoxified corn stover hydrolysate culture by SPSC01-TAF94, which achieved ethanol production and yield of 29.1 g·L–1 and 0.49 g·g–1, respectively, the growth and fermentation efficiency of acetic acid/furfural-based adaptive strain in hydrolysate was 95% higher than those of wildtype strains, indicating the acetic acid- and furfural-based adaptive evolution strategy could be an effective approach for improving lignocellulosic ethanol production. The adapted strains developed in this study with enhanced tolerance against acetic acid and furfural could be potentially contribute to economically feasible and sustainable lignocellulosic biorefinery.