title: Growth and ethanol fermentation ability on hexose and pentose sugars and glucose effect under various conditions in thermotolerant yeast Kluyveromyces marxianus.
abstract: Ethanol fermentation ability of the thermotolerant yeast Kluyveromyces marxianus, which is able to utilize various sugars including glucose, mannose, galactose, xylose, and arabinose, was examined under shaking and static conditions at high temperatures. The yeast was found to produce ethanol from all of these sugars except for arabinose under a shaking condition but only from hexose sugars under a static condition. Growth and sugar utilization rate under a static condition were slower than those under a shaking condition, but maximum ethanol yield was slightly higher. Even at 40°C, a level of ethanol production similar to that at 30°C was observed except for galactose under a static condition. Glucose repression on utilization of other sugars was observed, and it was more evident at elevated temperatures. Consistent results were obtained by the addition of 2-deoxyglucose. The glucose effect was further examined at a transcription level, and it was found that KmGAL1 for galactokinase and KmXYL1 for xylose reductase for galactose and xylose/arabinose utilization, respectively, were repressed by glucose at low and high temperatures, but KmHXK2 for hexokinase was not repressed. We discuss the possible mechanism of glucose repression and the potential for utilization of K. marxianus in high-temperature fermentation with mixed sugars containing glucose.
authors.affiliation: Graduate School of Medicine, Yamaguchi University, Ube, Yamaguchi, Japan.
authors.forename: Nadchanok
authors.initials: N
authors.lastname: Rodrussamee
authors.forename: Noppon
authors.initials: N
authors.lastname: Lertwattanasakul
authors.forename: Katsushi
authors.initials: K
authors.lastname: Hirata
authors.lastname: Suprayogi
authors.forename: Savitree
authors.initials: S
authors.lastname: Limtong
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Kosaka
authors.forename: Mamoru
authors.initials: M
authors.lastname: Yamada
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D006601:Hexoses / Q000378:metabolism*; D006358:Hot Temperature; D007716:Kluyveromyces / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D010429:Pentoses / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D006601:Hexoses; D010429:Pentoses; D000431:Ethanol; D005947:Glucose