Ishigami Mari, Nakagawa Youji, Hayakawa Masayuki, Iimura Yuzuru
Division of Biotechnology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan.
Biosci Biotechnol Biochem. 2006 Mar;70(3):660-6. doi: 10.1271/bbb.70.660.
Some strains of Saccharomyces cerevisiae form a biofilm called a "flor" on the surface of wine after ethanolic fermentation, but the molecular mechanism of flor formation by the wild-type flor strain involved in wine making is not clear. Previously, we found that expression of the C-terminally truncated form of NRG1 (NRG1(1-470)) on a multicopy plasmid increases the hydrophobicity of the cell surface, conferring flor formation on the non-flor laboratory strain. Here we show that in Ar5-H12, a wild-type flor haploid strain, flor formation is regulated by NRG1(1-470). Moreover, the disruptant of the wild-type flor diploid strain (Deltaflo11/Deltaflo11) show a weak ability to form the flor. The expression of FLO11 is always high in the wild-type flor strain, regardless of carbon source. Thus FLO11 is primary factor for wild-type flor strains. Furthermore, the disruptant (Deltaflo11) shows lower hydrophobicity of cell surface than the wild type. However, the hydrophobicity of the wild-type flor strains grown in ethanol medium was much higher than those grown in glucose medium. These results indicate that cell surface hydrophobicity is closely related to flor formation in wild-type flor yeasts.
一些酿酒酵母菌株在乙醇发酵后会在葡萄酒表面形成一种称为“酒花”的生物膜，但参与酿酒的野生型酒花菌株形成酒花的分子机制尚不清楚。此前，我们发现多拷贝质粒上C端截短形式的NRG1（NRG1(1-470)）的表达会增加细胞表面的疏水性，使非酒花实验室菌株具备形成酒花的能力。在此我们表明，在野生型酒花单倍体菌株Ar5-H12中，酒花的形成受NRG1(1-470)调控。此外，野生型酒花二倍体菌株（Deltaflo11/Deltaflo11）的缺失突变体形成酒花的能力较弱。无论碳源如何，FLO11在野生型酒花菌株中的表达始终很高。因此，FLO11是野生型酒花菌株的主要因素。此外，缺失突变体（Deltaflo11）的细胞表面疏水性低于野生型。然而，在乙醇培养基中生长的野生型酒花菌株的疏水性远高于在葡萄糖培养基中生长的菌株。这些结果表明，细胞表面疏水性与野生型酒花酵母中酒花的形成密切相关。
