Overexpression of Transcription Factor ZNF1 of Glycolysis Improves Bioethanol Productivity Under High Glucose Concentration and Enhances Acetic Acid Tolerance of Saccharomyces Cerevisiae

Saccharomyces cerevisiae offers an attractive platform for synthesis of biofuels and biochemical; however, robust strains that can withstand high substrate concentration and fermentation conditions are required. To improve the yield and productivity of bioethanol, modification of glucose metabolism and cellular stress adaptation was investigated. Specifically, we characterized the role of Znf1 transcription factor in metabolic regulation of glucose. Here, Znf1 was first shown to activate key genes in glycolysis, pyruvate metabolism and alcoholic fermentation when glucose is provided as the sole carbon source. Under conditions of high glucose (20 g/L), overexpression of ZNF1 accelerated glucose consumption with only 0.67-0.80% of glucose remaining after 24 or 36 h of fermentation. Importantly, ZNF1 overexpression increased ethanol concentrations by 14-24% and achieved a maximum ethanol concentration of 76.12-88.60 g/L. Ethanol productivity was increased to 3.17-3.69 in strains overexpressing ZNF1 compared to 2.42-3.35 and 2.94-3.50 for the znf1Delta and wild-type strains, respectively. Moreover, strains overexpressing ZNF1 also displayed enhanced tolerance to osmotic and weak-acid stresses, important trait in alcoholic fermentation. Overexpresssion of key transcriptional activators of genes in glycolysis and stress responses appears to be an effective strategy to improve bioethanol productivity and enhance strain robustness. This article is protected by copyright. All rights reserved.