In this study, we aimed to breed non-foaming sake yeast strains derived from Gifu University's original yeast strain GY115, and to identify suitable fermentation conditions for brewing a novel type of sake using one of these strains. First, five strains of non-foaming sake yeast from strain GY115 were bred using the froth flotation method. From these strains, we selected strain GY115-a3 as a candidate for the non-foaming Gifu University yeast strain because (i) it had the highest ethanol fermentation ability, (ii) sake brewed by the strain had a sharpness in taste, and (iii) it was a high acid-producing yeast, like strain GY115. Moreover, in a large-scale sake fermentation test at low temperature (maximum temperature of the sake mush was 10.2°C), strain GY115-a3 produced a unique type of sake, with a sweet and refreshing sour taste (sake meter value and acidity of -16.1 and 2.27, respectively). These results indicate the possibility of developing a new type of sake using the non-foaming sake yeast strain GY115-a3.

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We conducted an industry-academia collaboration of the Jizake brewing project, in order to revitalize our local area in Hidaka, Wakayama Prefecture. In order to do so, the Yeast DJJ01 was isolated from the Dojoji Temple, the oldest temple (founded in AD701) in Wakayama Prefecture. We can show the old tale of “Anchin & Kiyohime” such as scary romance story by old style picture scroll. In this study, we characterized the biochemical properties of the yeast DJJ01. First, we identified this yeast strain as Saccharomyces cerevisiae by conducting phylogenetic analysis of the strain's ITS1 region (DDBJ Accession No. LC405963). Our analysis also indicated that the strain's lactic acid component is more than yeast K7 during small brewing test. Meanwhile, pre-brewed sake contains a large amount of Ginjyo-ko such as ethyl caproate and isoamyl acetate.

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Batabata-cha is one of several post-fermented teas produced in Toyama. In the present study, microorganisms, fungi and bacteria involved in the fermentation of Batabata-cha were investigated. Aspergillus fumigatus was isolated from tea leaves after fermentation as fungi and Bacillus coagulans formed a colony on De Man, Rogosa, and Sharpe (MRS) agar as bacteria. According to an analysis of the internal transcribed spacers region, the dominant species of fungi was found to be Aspergillus fumigatus, while the subdominant species was Thermomyces lanuginosus. Eighty-five percent of total fungal flora was of the Aspergillus and Thermomyces species. Additionally, Saccharomyces cerevisiae and other various fungi were observed. According to an analysis of the 16S rRNA gene, the dominant species of bacteria was Niabella terrae (23.1％). Additionally, Actinomadura keratinilytica (8.6％), Sphingobacterium thermophilum (8.4％), Pseudoxanthomonas taiwanensis (8.3％), and Caenibacillus caldisaponilyticus (8.2％) were present. These microorganisms may contribute to the fermentation of Batabata-cha, with both Aspergillus fumigatus and Thermomyces lanuginosus being of particular importance. Because of fermentation heat the temperature of tea leaves reached 70 °C; thus, thermophilic microorganisms or sporeforming bacteria were frequently observed. In the fermentation process of Batabata-cha, fermentation heat is an important selection pressure for fermentation microorganisms; therefore, temperature regulation is essential for a stable and high-quality production of Batabata-cha.

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[in Japanese]

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