Analysis of the effect of ATG34 gene overexpression on acetic acid tolerance of Saccharomyces cerevisiae

Abstract

At present, global energy security continues to face threats, in order to ensure sustainable energy and improve energy efficiency, to alleviate global warming, the transformation from traditional fossil fuels to clean energy has been vigorously promoted. The second generation of fuel ethanol is derived from lignocellulosic biomass by microbial fermentation, which has the advantages of low cost, renewable and environmental protection. Lignocellulose is composed of hemicellulose, cellulose and lignin. Its complex structure can not be directly utilized by microorganisms, so it needs to undergo pretreatment and hydrolysis process to generate fermentable monosaccharides before they can be utilized by microorganisms. However, lignocellulose produces a large number of small molecule compounds during the pretreatment process, which inhibits the fermentation process of microorganisms. Among them, acetic acid is a common inhibitor in a variety of lignocellulosic biomass hydrolytic components, which inhibits the growth and metabolism of yeast cells during fermentation, leading to ATP starvation and oxidative stress, which in turn leads to poor production of lignocellulosic biomass fuels and chemicals. Therefore, the acetic acid tolerance of microorganisms will directly affect the production efficiency of second-generation ethanol from lignocellulose. Saccharomyces cerevisiae is the preferred strain for producing second-generation ethanol because of its high sugar, high ethanol and low pH tolerance. However, the bacteria had a weak tolerance to small molecule inhibitors produced during lignocellulosic pretreatment. A histone point mutant with high acetic acid tolerance was screened in the previous laboratory work. Transcriptome sequencing analysis showed that the expression level of ATG34 gene in the histone point mutant was significantly increased. In order to verify the effect of ATG34 gene on acetic acid tolerance of strains, we overexpressed the ATG34 gene of the parent strains, and found that the acetic acid tolerance of strains overexpressed by ATG34 was significantly improved through the growth curve. The results provided an effective reference for the construction of the second generation ethanol production strains with high acetic acid tolerance.