A study on the yeast Saccharomyces cerevisiae isolates from the Shirakami Mountains, with a focus on their phylogenetic traits.
1Faculty of Agriculture and Life Science, Hirosaki University
The yeast Saccharomyces cerevisiae is widely used in the production of fermented beverages and breads; however its ecology and distribution in nature are still poorly understood. The Shirakami Mountains, a mountain range located in the northern Japan, has been a World Natural Heritage area since 1993 and is famous for its virgin beech forests and is little affected by anthropic pressures. Here, we studied S. cerevisiae inhabiting the Shirakami Mountains, with particular emphasis on their phylogenetic traits.
Yeast strains were isolated from sources such as decomposing leaf litter, barks, soil, and flowers, from various sites in the Shirakami Mountains, by using medium containing 7.6 % ethanol and identified based on the sequence of the ITS region of the rDNA. The yeast strains identified as S. cerevisiae were applied to molecular phylogenetic analysis using SNPs from several loci.
【Results and Conclusions】
As of August 10, 2015, we have successfully isolated 46 strains of S. cerevisiae from 848 samples. The predominant sources were decomposing leaf litter of Japanese oak and beech. S. cerevisiae and S. paradoxus, both of which are species of Saccharomyces sensu stricto, were predominantly isolated from enrichment cultures, indicating sympatric speciation as reported previously. Molecular phylogenetic analysis suggested that these isolates formed some linages that were distinct from other groups of S. cerevisiae, including sake yeasts, wine yeasts, or yeasts from environments with a lot of human activity, such as parks and orchards. These results suggest that S. cerevisiae inhabiting the Shirakami Mountains have evolved independently of other S. cerevisiae linages. As part of our future study, we are currently attempting to distinguish sympatric S. cerevisiae and S. paradoxus in terms of physiological and biochemical characteristics and analyze the genome of the S. cerevisiae strain from the Shirakami Mountains.
keywords:*Saccharomyces cerevisiae*,The Sirakami Mountains,Phylogenetic Analysis