Improved growth and ethanol fermentation of Saccharomyces cerevisiae in the presence of acetic acid by overexpression of SET5 and PPR1

• Published in: Biotechnology journal 2015-12, Vol.10 (12), p.1903-1911
• Main Authors: Zhang, Ming-Ming, Zhao, Xin-Qing, Cheng, Cheng, Bai, Feng-Wu
• Format: Article
• Language: English
• Subjects: Acetic acid; Acetic Acid - metabolism; Adenosine Triphosphate - metabolism; Biological Phenomena; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Ethanol - metabolism; Ethanol production; Fermentation; PPR1; Reactive Oxygen Species - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; SET5; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - metabolism; Zea mays - chemistry; Zinc Fingers
• ISSN: 1860-6768; 1860-7314
• DOI: 10.1002/biot.201500508

To better understand the contribution of zinc‐finger proteins to environmental stress tolerance, particularly inhibition from acetic acid, which is a potent inhibitor for cellulosic ethanol production by microbial fermentations, SET5 and PPR1 were overexpressed in Saccharomyces cerevisiae BY4741. With 5 g/L acetic acid addition, engineered strains BY4741/SET5 and BY4741/PPR1 showed improved growth and enhanced ethanol fermentation performance compared to that with the control strain. Similar results were also observed in ethanol production using corn stover hydrolysate. Further studies indicated that SET5 and PPR1 overexpression in S. cerevisiae significantly improved activities of antioxidant enzymes and ATP generation in the presence of acetic acid, and consequently decreased intracellular accumulation of reactive oxygen species (50.9 and 45.7%, respectively). These results revealed the novel functions of SET5 and PPR1 for the improvement of yeast acetic acid tolerance, and also implicated the involvement of these proteins in oxidative stress defense and energy metabolism in S. cerevisiae. This work also demonstrated that overexpression of SET5 and PPR1 would be a feasible strategy to increase cellulosic ethanol production efficiency. One of the bottlenecks of the lignocellulosic biofuels production is the toxicity of inhibitory compounds, especially acetic acid. The authors demonstrate that SET5 or PPR1 overexpression in Saccharomyces cerevisiae improves growth and enhance ethanol production performance in the presence of acetic acid. Meanwhile, variation of transcription level of key stress‐responsive regulatory genes, the elevated ATP level and activities of antioxidant enzymes (including total SOD and CAT) are observed in the overexpressing strains, which may be the reason of the decreased ROS accumulation. This article is part of an AFOB (Asian Federation of Biotechnology) Special issue. To learn more about the AFOB, visit www.afob.org.