Identification of tetrodotoxin in marine sediments and screening for its biosynthetic genes in marine soil bacteria

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K22266
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 38:Agricultural chemistry and related fields
• Research Institution: Tohoku University
• Principal Investigator: Yamashita Mari 東北大学, 農学研究科, 教授 (50192430)
• Project Period (FY): 2019-06-28 – 2022-03-31
• Keywords: テトロドトキシン / 麻痺性貝毒 / 生合成 / ホタテガイ

Outline of Final Research Achievements

Tetrodotoxin (TTX) is detected in some marine animals, pufferfish, crabs, octopuses, etc., and bacterial production of TTX has been reported. However, the questions such as, where TTX is produced, and why TTX is widely distributed among marine organisms, have not been well answered yet. Biosynthetic genes of TTX have not been identified neither. In this study, we analyzed TTX in marine sediments, and in the scallops cultured in a bay of East Japan, which were temporally collected for three years. TTX was clearly detected in the marine sediment one time. TTX in the scallops was identified by LCMS for the first time in Japanese bivalves. However, the TTX concentrations in the edible tissues were confirmed to be lower than the restricted concentration proposed by European Food Safety Authority (EFSA). The concentrations of TTX in scallops repeatedly increased from August to October in three years.

Free Research Field

天然物化学

Academic Significance and Societal Importance of the Research Achievements

本研究では、未解明のTTX生合成を解決するために、海底土壌サンプルのTTX分析や、海底付近の微小生物のDNA網羅的解析を行い、TTX生合成遺伝子を探索した。さらに、海水中に吊るして養殖したホタテガイを分析し、微量のTTXを国内で初めてLCMSで同定した。また、TTXは8月-10月にかけてピークを示すことを初めて示した。これらは、海洋生物のTTX毒化メカニズム解明において、学術的意義がある。また、ホタテガイ可食部のTTX濃度は食品衛生的に問題のないレベルであることを明らかにし、社会的意義もある。