title: Development of industrial yeast strain with improved acid- and thermo-tolerance through evolution under continuous fermentation conditions followed by haploidization and mating.
abstract: Continuous fermentation using the industrial Saccharomyces cerevisiae diploid strain WW was carried out under acidic or high-temperature conditions to achieve acid- or thermo-tolerant mutants. Mutants isolated at pH 2.5 and 41°C showed improved growth and fermentation ability under acidic and elevated temperature conditions. Haploid strains WW17A1 and WW17A4 obtained from the mutated diploid strain WW17A showed better growth and 4.5-6.5% higher ethanol yields at pH 2.7 than the original strains. Haploid strain WW12T4 obtained from mutated diploid strain WW12T showed 1.25-1.50 times and 2.8-4.7 times higher total cell number and cell viability, respectively, than the original strains at 42°C. Strain AT, which had significantly improved acid- and thermo-tolerance, was developed by mating strain WW17A1 with WW12T4. Batch fermentation at 41°C and pH 3.5 showed that the ethanol concentration and yield achieved during fermentation by strain AT were 55.4 g/L and 72.5%, respectively, which were 10 g/L and 13.4% higher than that of the original strain WW. The present study demonstrates that continuous cultivation followed by haploidization and mating is a powerful approach for enhancing the tolerance of industrial strains.
authors: Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-0862, Japan.
authors: Kanako
authors: K
authors: Mitsumasu
authors: College of Engineering, Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing 100871, China.
authors: Ze-Shen
authors: ZS
authors: Liu
authors: College of Engineering, Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing 100871, China; College of Architecture and Environment, Sichuan University, No. 24, South Section 1, First Ring Road, Chengdu, Sichuan 610065, China. Electronic address: tangyueqin@pku.edu.cn.
authors: Yue-Qin
authors: YQ
authors: Tang
authors: Department of Applied Microbial Technology, Sojo University, 4-22-1 Ikeda, Nishi-ku, Kumamoto 860-0082, Japan.
authors: Takashi
authors: T
authors: Akamatsu
authors: Department of Applied Microbial Technology, Sojo University, 4-22-1 Ikeda, Nishi-ku, Kumamoto 860-0082, Japan.
authors: Hisataka
authors: H
authors: Taguchi
authors: College of Architecture and Environment, Sichuan University, No. 24, South Section 1, First Ring Road, Chengdu, Sichuan 610065, China.
authors: Kenji
authors: K
authors: Kida
mesh_terms: D000064:Acclimatization / Q000187:drug effects* / Q000235:genetics; D000143:Acids / Q000494:pharmacology; D005075:Biological Evolution; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D006238:Haploidy; D006863:Hydrogen-Ion Concentration; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D013696:Temperature
chemical_list: D000143:Acids; D029701:Saccharomyces cerevisiae Proteins; D000431:Ethanol
keywords: Acid-tolerance; Ethanol fermentation; Evolutionary engineering; Haploidization and mating; Saccharomyces cerevisiae; Strain development; Thermo-tolerance