Enhanced acetic acid stress tolerance and ethanol production in Saccharomyces cerevisiae by modulating expression of the de novo purine biosynthesis genes

Ming-Ming Zhang; Liang Xiong; Ya-Jie Tang; Muhammad Aamer Mehmood; Zongbao Kent Zhao; Feng-Wu Bai; Xin-Qing Zhao

doi:10.1186/s13068-019-1456-1

Enhanced acetic acid stress tolerance and ethanol production in Saccharomyces cerevisiae by modulating expression of the de novo purine biosynthesis genes

Biotechnol Biofuels. 2019 May 10:12:116. doi: 10.1186/s13068-019-1456-1. eCollection 2019.

Authors

Ming-Ming Zhang¹, Liang Xiong², Ya-Jie Tang^{3

4}, Muhammad Aamer Mehmood^{1

5}, Zongbao Kent Zhao⁶, Feng-Wu Bai¹, Xin-Qing Zhao¹

Affiliations

¹ 1State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240 China.
² 3School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024 China.
³ 2Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei Key Laboratory of Industrial Microbiology, Hubei University of Technology, Wuhan, 430068 China.
⁴ 5State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237 China.
⁵ 6Department of Bioinformatics & Biotechnology, Government College University Faisalabad, Faisalabad, 38000 Pakistan.
⁶ 4Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023 China.

Abstract

Background: Yeast strains that are tolerant to multiple environmental stresses are highly desired for various industrial applications. Despite great efforts in identifying key genes involved in stress tolerance of budding yeast Saccharomyces cerevisiae, the effects of de novo purine biosynthesis genes on yeast stress tolerance are still not well explored. Our previous studies showed that zinc sulfate addition improved yeast acetic acid tolerance, and key genes involved in yeast stress tolerance were further investigated in this study.

Results: Three genes involved in de novo purine biosynthesis, namely, ADE1, ADE13, and ADE17, showed significantly increased transcription levels by zinc sulfate supplementation under acetic acid stress, and overexpression of these genes in S. cerevisiae BY4741 enhanced cell growth under various stress conditions. Meanwhile, ethanol productivity was also improved by overexpression of the three ADE genes under stress conditions, among which the highest improvement attained 158.39% by ADE17 overexpression in the presence of inhibitor mixtures derived from lignocellulosic biomass. Elevated levels of adenine-nucleotide pool "AXP" ([ATP] + [ADP] + [AMP]) and ATP content were observed by overexpression of ADE17, both under control condition and under acetic acid stress, and is consistent with the better growth of the recombinant yeast strain. The global intracellular amino acid profiles were also changed by overexpression of the ADE genes. Among the changed amino acids, significant increase of the stress protectant γ-aminobutyric acid (GABA) was revealed by overexpression of the ADE genes under acetic acid stress, suggesting that overexpression of the ADE genes exerts control on both purine biosynthesis and amino acid biosynthesis to protect yeast cells against the stress.

Conclusion: We proved that the de novo purine biosynthesis genes are useful targets for metabolic engineering of yeast stress tolerance. The engineered strains developed in this study with improved tolerance against multiple inhibitors can be employed for efficient lignocellulosic biorefinery to produce biofuels and biochemicals.

Keywords: ADE17; Global amino acid profiles; Saccharomyces cerevisiae; Yeast stress tolerance; de novo purine biosynthesis.