title: Isolation of aquatic yeasts with the ability to neutralize acidic media, from an extremely acidic river near Japan's Kusatsu-Shirane Volcano.
abstract: The Yukawa River is an extremely acidic river whose waters on the east foot of the Kusatu-Shirane Volcano (in Gunma Prefecture, Japan) contain sulfate ions. Here we isolated many acid-tolerant yeasts from the Yukawa River, and some of them neutralized an acidic R2A medium containing casamino acid. Candida fluviatilis strain CeA16 had the strongest acid tolerance and neutralizing activity against the acidic medium. To clarify these phenomena, we performed neutralization tests with strain CeA16 using casamino acid, a mixture of amino acids, and 17 single amino acid solutions adjusted to pH 3.0, respectively. Strain CeA16 neutralized not only acidic casamino acid and the mixture of amino acids but also some of the acidic single amino acid solutions. Seven amino acids were strongly decomposed by strain CeA16 and simultaneously released ammonium ions. These results suggest strain CeA16 is a potential yeast as a new tool to neutralize acidic environments.
authors.affiliation: Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato, Tokyo 108-8477, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Mitsuya
authors.affiliation: Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato, Tokyo 108-8477, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Hayashi
authors.affiliation: Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato, Tokyo 108-8477, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato, Tokyo 108-8477, Japan.
authors.forename: Mami
authors.initials: M
authors.lastname: Tanaka
authors.affiliation: Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato, Tokyo 108-8477, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Okai
authors.affiliation: Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato, Tokyo 108-8477, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Ishida
authors.affiliation: Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato, Tokyo 108-8477, Japan. Electronic address: urano@kaiyodai.ac.jp.
authors.forename: Naoto
authors.initials: N
authors.lastname: Urano
mesh_terms: D002175:Candida / Q000302:isolation & purification* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007564:Japan; D045483:Rivers / Q000737:chemistry*
keywords: Acid tolerance; Acid-tolerant yeast; Acidic river; Candida fluviatilis; Neutralization