title: Characterization and gene expression profiles of thermotolerant Saccharomyces cerevisiae isolates from Thai fruits.
abstract: For industrial applications, fermentation of ethanol at high temperature offers advantages such as reduction in cooling costs, reduced risk of microbial contamination and higher efficiency of fermentation processes including saccharification and continuous ethanol stripping. Three thermotolerant Saccharomyces cerevisiae isolates (C3723, C3751 and C3867) from Thai fruits were capable of growing and producing 38 g/L ethanol up to 41°C. Based on genetic analyses, these isolates were prototrophic and homothallic, with dominant homothallic and thermotolerant phenotypes. After short-term (30 min) and long-term (12 h) exposure at 37°C, expression levels increased for the heat stress-response genes HSP26, SSA4, HSP82, and HSP104 encoding the heat shock proteins small HSP, HSP70, HSP90 and the HSP100 family, respectively. In isolates C3723 and C3867, expression was significantly higher than that in reference isolates W303 and TISTR5606 for TPS1 encoding trehalose-6-phosphate synthase, NTH1 encoding neutral trehalase and GSY1 encoding glycogen synthase. The results suggested that continuous high expression of heat stress-response genes was important for the long-term, heat stress tolerance of these thermotolerant isolates.
authors.affiliation: Department of Biology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Choowong
authors.initials: C
authors.lastname: Auesukaree
authors.forename: Preeyaporn
authors.initials: P
authors.lastname: Koedrith
authors.forename: Pornpon
authors.initials: P
authors.lastname: Saenpayavai
authors.forename: Thipa
authors.initials: T
authors.lastname: Asvarak
authors.forename: Suthee
authors.initials: S
authors.lastname: Benjaphokee
authors.forename: Minetaka
authors.initials: M
authors.lastname: Sugiyama
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Satoshi
authors.initials: S
authors.lastname: Harashima
authors.forename: Chuenchit
authors.initials: C
authors.lastname: Boonchird
mesh_terms: D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D005638:Fruit / Q000382:microbiology*; D015966:Gene Expression Regulation, Fungal / Q000235:genetics*; D005800:Genes, Fungal; D005964:Glucosyltransferases / Q000235:genetics; D018869:Heat-Shock Response / Q000235:genetics; D006358:Hot Temperature; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome; D014198:Trehalase / Q000235:genetics; D014199:Trehalose / Q000096:biosynthesis / Q000378:metabolism
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D000431:Ethanol; D014199:Trehalose; D005964:Glucosyltransferases; C023180:trehalose-6-phosphate synthase; D014198:Trehalase