Genome-based approaches for monitoring and controlling neurotoxin-producing cyanobacteria in lakes

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K05785
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 40030:Aquatic bioproduction science-related
• Research Institution: Chubu University (2021-2022); Ibaraki Kasumigaura Environmental Science Center (2020); Kyoto University (2018-2019)
• Principal Investigator: Hodoki Yoshikuni 中部大学, 応用生物学部, 准教授 (60632122)
• Co-Investigator(Kenkyū-buntansha): 朴 虎東 信州大学, 学術研究院理学系, 教授 (20262686)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: シアノバクテリア / シアノトキシン / 湖沼 / ゲノム

Outline of Final Research Achievements

Genomic and environmental characteristics of neurotoxin anatoxin-a-producing cyanobacterium Cuspidothrix issatschenkoi were evaluated. Toxic strains already determined their genomes differ in the presence or absence of nitrogen-fixing genes and producing cyanotoxins. They also have many transposon-related genes, which would be related to the diversity of environmental characteristics of this species. On the other hand, it is difficult to quantify the toxic strains in water systems because mutations occur in multiple regions in the toxin synthesis gene. It was also suggested that the distribution of virulent strains, which were not distributed in Japan or appeared only rarely, may be expanding.

Free Research Field

陸水学

Academic Significance and Societal Importance of the Research Achievements

日本および海外で分離培養されたシアノバクテリアCuspidothrix issatschenkoiの神経毒アナトキシン-a合成遺伝子を比較したところ、合成遺伝子上の複数の個所で欠損が生じ有毒株が無毒株化していることが明らかとなり、毒合成遺伝子の特定の領域を定量PCRなどで増幅・定量することによって有毒株の現存量を評価するのは困難であると考えられた。また、愛知県のため池より肝臓毒シリンドロスペルモプシンと神経毒サキシトキシンの合成遺伝子が検出され、この10年の間に、これまで日本に分布していなかったか稀にしか出現しなかった有毒株の分布が拡大している可能性が示唆された。