@article{oai:repo.qst.go.jp:00085281,
 author = {Watanabe, Takashi and Yanagisawa, Masaomi and Katsuya, Sato and Yutaka, Ono and Katsuya, Sato and Yutaka, Ono},
 journal = {QST Takasaki Annual Report 2020},
 month = {Mar},
 note = {Gunma KAZE yeasts, bred for ginjyo-sake brewing, are utilized in many sake-manufactures of Gunma prefecture. Urea is a main precursor in Japanese sake of ethyl carbamate which is classified in the group 2A “probably the cause of cancer” by International Agency for Research on Cancer. We previously bred non-urea producing Gunma KAZE1 yeast (KAZE1-Arg) by natural mutation and Gunma KAZE2 yeast (KAZE2-Arg) by ion-beam irradiation. However, the growth of Gunma KAZE3 yeast (KAZE3), the second most utilized strain in Gunma prefecture, could not be suppressed on modified CAO medium. On the other hand, we improved the viability of sake yeasts prepared for ion-beam mutagenesis. Thus, in this year, we attempted to improve the medium condition to suppress cell growth and isolate non-urea producing candidates from KAZE3. KAZE3 cells were irradiated with carbon ion beams (12C5+, 220 MeV, 200 - 300 Gy) accelerated by using the AVF cyclotron at TIARA, TARRI, QST. Twenty-two candidates were obtained after 5 weeks cultivation on the medium. From these 22 candidates, 17 arginase-inactivate mutants were selected as non-urea producing mutants. To investigate fermentation ability, ginjyo-aroma productivity and urea-productivity, laboratory scale sake brewing experiment was performed. All mutants did not produce urea. However, 11 mutants changed the brewing profiles. Six mutants were selected for future experiments.},
 title = {Isolation of non-urea producing candidates from Gunma KAZE3 yeast by ion-beam mutagenesis},
 volume = {QST-M-33},
 year = {2022}
}