2018 Fiscal Year Final Research Report

Molecular mechanism of neutralization of acid envirnments by alkalinization yeasts and their enzymes

Research Project

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Project/Area Number	16K07868
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Aquatic life science
Research Institution	Tokyo University of Marine Science and Technology
Principal Investigator	Urano Naoto 東京海洋大学, 学術研究院, 教授 (90262336)
Co-Investigator(Kenkyū-buntansha)	岡井公彦東京海洋大学, 学術研究院, 助教 (00596562) 石田真巳東京海洋大学, 学術研究院, 教授 (80223006)
Project Period (FY)	2016-04-01 – 2019-03-31
Keywords	酵母 / 強酸性水 / 中和 / pH耐性 / 分子機構 / 酵素
Outline of Final Research Achievements	Alkalinization yeasts have neutralizing activities of strongly acidified water by producing anmonium ions. The yeasts were cultivated in acid, neutral, or basic water and their protein biosynthesis in the cells changed little. The yeasts produced anmonium ions in each water. Production of organic acids by the yeasts increased in both neutral and basic water. Therefore, they were found to regulate pH by changing the pruductions of anmonium ions and organic acids accoding to environmental pH. Alkalinization yeasts were found to live in natural acid, neutral or basic environments. The yeast species were almost same, had broad range of pH tolerance, and lived in the environments from acid to basic. Continous neutralization of strongly acidified water and removal of surplus anmonium ions were attained by a bioreactor with immobilized yeasts and zeolite.
Free Research Field	環境微生物化学
Academic Significance and Societal Importance of the Research Achievements	日本にはpH1-3の強酸性の第1級河川が幾つか存在する。こうした河川では魚介類が生息せず、農業用水や養殖水にも使用できない死の川と言われてきた。石灰投与による中和事業が進み、中和工場に下流からは、河川に中和水が流れるようになった。一方で石灰による2次汚染も発生して、あるレベルでの石灰耐性を持つ魚介類しか生息できない水圏環境となっている。アルカリ化酵母は、アンモニウムイオンを生成することで強酸性水を中和する能力を持つ。当該酵母により強酸性水を中和して、過剰な案もアンモニウムイオンを吸着除去することで、環境に優しい中和が実現できる。本研究成果は生活水や農業用水の製造に利用可能と考えている。