Study on osmotolerance of microorganisms isolated from honey

• Project/Area Number: 16K00826
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Eating habits
• Research Institution: Tokyo University of Agriculture
• Principal Investigator: TAMURA Tomoko 東京農業大学, 応用生物科学部, 准教授 (60451845)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000); Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2017: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2016: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
• Keywords: Zygosaccharomyces mellis / 耐糖性 / RNA-Seq / トランスクリプトーム解析 / オルソログ解析 / RT-PCR / 糖耐性 / タンパク質発現ベクター / 浸透圧耐性 / 耐糖メカニズム / ストレス応答

Outline of Final Research Achievements

Osmotolerant microorganisms can survive in high salt/sugar environment. Zygosaccharomyces mellis can grow in preserved food such as honey and maple syrup. Zygosaccharomyces rouxii can grow in soy sauce and miso, which are traditional fermented foods in Japan containing high amounts of salt. Z. mellis is known to deteriorate the quality of honey. We isolated Z. mellis from purchased honey imported from Canada. The strain was able to grow in the YM medium (0.3% yeast extract, 0.3% malt extract, and 0.5% polypepton) with 60% glucose, in which Saccharomyces cerevisiae cannot survive. In the environment, gene expression related to glyconeogenesis was down-regulated. On the other hand, genes associated with cell-wall synthesis were up-regulated.
Orthologue analysis showed that the number of genes expressing only in Z. mellis was 174, and contained genes encoding methylglyoxal reductase, cytochrome c oxidase, beta-glucan synthesis-associated protein, and translation elongation factor.

Academic Significance and Societal Importance of the Research Achievements

食の安全と衛生の担保に注目が集まる中、食品の加工や保蔵環境下における酵母の環境応答を明らかにすることは食品の品質保持のために重要である。本研究はAw活性の低い保存食品から酵母の一種であるZ. mellisを単離しその高糖度耐性能に関わる遺伝子とその発現変動を解析した。
食品の品質保持において食品の加工の工夫だけでなく、品質を劣化させる条件のうち大きな割合を占める微生物の高糖度耐性の仕組みに迫ったことは、食品保蔵の改善の一助となると考えられる。