Chromosomal structure of lager brewing yeasts assessed with a newly developed lager brewing yeast DNA microarray.
Yukiko Kodama (1), Yoshihiro Nakao (1), Tomoko Fujimura (1), Norihisa Nakamura (1), Wataru Miki (1), Takehiko Ito (2), Katsuhiko Shirahige (3), Toshihiko Ashikari (4)
(1) Inst. for Advanced Technology, Suntory Ltd., 1-1-1, Wakayamadai, Osaka, 618-8503, Japan; (2) Mitsubishi Research Institute, INC., 2-3-6, Otemachi, Chiyoda-ku, Tokyo, 100-8141 Japan; (3) Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8501, Japan; (4) Florigene, 16 Gipps Street Collingwood VIC 3066, Australia
Lager brewing yeast, Saccharomyces pastorianus, is a natural hybrid between S. cerevisiae and a closely related Saccharomyces species. We have sequenced the whole genome of a representative lager brewing strain (Weihenstephan 34/70) and found that it indeed contains two divergent genomes whose DNA identities to S. cerevisiae are; higher than 98% (Sc type genome) and approximately 85% (non-Sc type genome), respectively. Furthermore, we have shown that lager strains have three types of chromosomes: 1) Sc type, 2) non-Sc type and 3) mosaic type composed of segments from Sc and non-Sc type chromosomes. Our lager brewing yeast sequence has been employed to construct a specific DNA microarray containing all of the lager brewing yeast ORFs and intergenic regions. Using this array, we carried out comparative genomic hybridization (CGH) on a number of lager brewing yeasts and on some other closely related Saccharomyces strains. Most of the lager yeasts tested resulted nearly identical to the sequenced strain, whereas some strains showed different translocation points in the mosaic type chromosomes. Furthermore, we noticed that several chromosomes of the type strains of S. pastorianus CBS1538, S. monacensis CBS1503, S. carlsbergensis NBRC 11023 and of lager strains formerly defined as Saaz type lack the Sc type genome and possess only the non-Sc type genome. From these results, the genome evolution of lager brewing yeasts will be discussed.