title: Improved ethanol tolerance of Saccharomyces cerevisiae in mixed cultures with Kluyveromyces lactis on high-sugar fermentation.
abstract: The influence of non-Saccharomyces yeast, Kluyveromyces lactis, on metabolite formation and the ethanol tolerance of Saccharomyces cerevisiae in mixed cultures was examined on synthetic minimal medium containing 20% glucose. In the late stage of fermentation after the complete death of K. lactis, S. cerevisiae in mixed cultures was more ethanol-tolerant than that in pure culture. The chronological life span of S. cerevisiae was shorter in pure culture than mixed cultures. The yeast cells of the late stationary phase both in pure and mixed cultures had a low buoyant density with no significant difference in the non-quiescence state between both cultures. In mixed cultures, the glycerol contents increased and the alanine contents decreased when compared with the pure culture of S. cerevisiae. The distinctive intracellular amino acid pool concerning its amino acid concentrations and its amino acid composition was observed in yeast cells with different ethanol tolerance in the death phase. Co-cultivation of K. lactis seems to prompt S. cerevisiae to be ethanol tolerant by forming opportune metabolites such as glycerol and alanine and/or changing the intracellular amino acid pool.
authors.affiliation: Mie Prefecture Industrial Research Institute, 5-5-45 Takajaya, Tsu, Mie 514-0819, Japan.
authors.forename: Chizuru
authors.initials: C
authors.lastname: Yamaoka
authors.affiliation: Mie Prefecture Industrial Research Institute, 5-5-45 Takajaya, Tsu, Mie 514-0819, Japan. Electronic address: o-kurita@m2.cty-net.ne.jp.
authors.forename: Osamu
authors.initials: O
authors.lastname: Kurita
authors.affiliation: Mie Prefecture Industrial Research Institute, 5-5-45 Takajaya, Tsu, Mie 514-0819, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000409:Alanine / Q000378:metabolism; D000596:Amino Acids; D000431:Ethanol / Q000378:metabolism* / Q000494:pharmacology*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D007716:Kluyveromyces / Q000254:growth & development / Q000378:metabolism*; D056265:Microbial Interactions; D050296:Microbial Viability / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D000431:Ethanol; D005947:Glucose; D000409:Alanine; D005990:Glycerol
keywords: Cell death; Ethanol tolerance; Kluyveromyces lactis; Mixed culture; Saccharomyces cerevisiae