2022 Fiscal Year Final Research Report
Studies on diversity of Flavobacterium psychrophilum from Oncorhynchus keta fry as revealed by Multilocus Sequence Typing and their phenotypes
Project/Area Number |
20K06212
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Multi-year Fund |
Section | 一般 |
Review Section |
Basic Section 40030:Aquatic bioproduction science-related
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Research Institution | Kitasato University |
Principal Investigator |
Kasai Hiroaki 北里大学, 海洋生命科学部, 特任教授 (00221870)
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Project Period (FY) |
2020-04-01 – 2023-03-31
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Keywords | シロサケ / 健苗生産 / 冷水病菌 / 遺伝的多様性 / バイオフィルム |
Outline of Final Research Achievements |
Chum salmon is an important species for coastal fisheries in Hokkaido and Sanriku area, Japan. However, studies on the genetic diversity of Flavobacterium psychrophilum are limited. We isolated 131 strains of 20 species from the gills, body surface, and kidney of juveniles that showed frail swimming at a salmon hatchery in Iwate Prefecture. Among them, 16 strains were identified as F. psychrophilum, and genetic diversity was analyzed by Multi-Locus Sequence Typing based on 7 kinds of genes. As a result, five strains showed novel genotypes. In addition, cold water disease was detected in the white salmon larva breeding tank by the PCR method, and a high concentration of F. psychrophilum was detected on the surface layer of the larval fish bed and the eggs infected with the mold. A phenotypic comparison of the newly isolated strains revealed the ability to adhere to hydrophobic surfaces. Hydrophobic surface-adhering strains may form biofilms in juvenile rearing environments.
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Free Research Field |
微生物学
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Academic Significance and Societal Importance of the Research Achievements |
シロサケは北海道と岩手県を中心に年間14億尾以上の稚魚がサケ孵化場で生産放流されている最重要魚種であるにも関わらず、健康な放流種苗の生産に影響する冷水病の原因菌種についての系統的な遺伝子型の解析例はなかった。岩手県水産技術センターでは、海況が変動する中でも母川回帰する頑健な稚魚の生産するために、県内のさけます孵化場における放流用稚魚の飼育の履歴を詳細に調査し、冷水病の発生状況についても実態を把握している。我々は、冷水病菌及びその類縁菌の解析結果をデーターベースに蓄積すると共に生産現場にフィードバックすることによって、東日本大震災津波被災以前から低迷している親魚の回帰率向上に貢献する。
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