Microbial Ecology and Microorganisms Genomics Laboratory, Istituto Zooprofilattico Sperimentale Delle Venezie, PD, Viale Dell'Università 10, 35020, Legnaro, Italy.
National Reference Laboratory for Marine Biotoxins, Fondazione Centro Ricerche Marine, Viale A. Vespucci 2, 47042, Cesenatico, FC, Italy.
Chemosphere. 2023 Oct;339:139682. doi: 10.1016/j.chemosphere.2023.139682. Epub 2023 Jul 30.
Tetrodotoxins (TTXs) are potent neurotoxins named after the Tetraodontidae fish family. The ingestion of TTX-contaminated flesh can cause neurotoxic symptoms and can lead to death. In 2017 symptoms the European Food Safety Authority (EFSA) recognized the threat to food safety resulting from TTX exposure via food consumption and, thus, proposed a safety limit of 44 μg/kg of TTX in marine gastropods and bivalves. To date, however, TTXs have not yet been included in the list of biotoxins to be monitored within the European Union, even though, in a few cases, levels of TTX found were higher than the EFSA limit. The origin of TTX production is debated and the roles of both biotic and abiotic factors on TTX-mediated toxic events remain unclear. In order to meet these knowledge requests the present study was aimed to investigate the role of seawater temperature, pH, water conductivity, and oxygen saturation, along with the marine phytoplankton community and the bacterial community of mussels and oysters on the accumulation of TTX and analogues in the bivalves. Abiotic parameters were measured by means of a multi-parametric probe, phytoplankton community was analyzed by optic microscopy while microbial community was described by amplicon metataxonomic sequencing, TTXs concentration in the collected matrices were measured by HILIC-MS/MS. A possible role of seawater pH and temperature, among the investigated abiotic factors, in regulating the occurrence of TTXs was found. Regarding biotic variables, a possible influence of Vibrio, Shewanella and Flavobacteriaceae in the occurrence of TTXs was found. Concurrently, Prorocentrum cordatum cell numbers were correlated to the incidence of TTX in mussels. The results herein collected suggest that environmental variables play a consistent part in the occurrence of TTX in the edible bivalve habitats, and there are also indications of a potential role played by specific bacteria taxa in association with phytoplankton.
河豚毒素（TTXs）是一种以 Tetraodontidae 鱼类命名的强效神经毒素。摄入含有 TTX 的肉会引起神经毒性症状，并可能导致死亡。2017 年，欧洲食品安全局（EFSA）认识到通过食物摄入 TTX 对食品安全造成的威胁，并因此提议将海洋腹足纲动物和双壳类动物中的 TTX 安全限量设定为 44μg/kg。然而，迄今为止，TTX 尚未被列入欧盟监测的生物毒素清单，尽管在某些情况下，TTX 的含量高于 EFSA 的限量。TTX 产生的来源存在争议，生物和非生物因素在 TTX 介导的毒性事件中的作用仍不清楚。为了满足这些知识需求，本研究旨在调查海水温度、pH 值、水导电性和氧气饱和度，以及海洋浮游植物群落和贻贝和牡蛎的细菌群落，对双壳类动物中 TTX 和类似物积累的影响。通过多参数探头测量非生物参数，通过光学显微镜分析浮游植物群落，通过扩增子分类学测序描述微生物群落，通过亲水相互作用色谱-串联质谱法测量采集基质中的 TTX 浓度。发现调查的非生物因素中，海水 pH 值和温度可能在调节 TTXs 的发生方面发挥作用。关于生物变量，发现 Vibrio、Shewanella 和 Flavobacteriaceae 可能对 TTXs 的发生有影响。同时，Prorocentrum cordatum 细胞数量与贻贝中 TTX 的发生呈正相关。本研究结果表明，环境变量在可食用双壳类动物栖息地 TTX 的发生中起着一致的作用，并且还表明特定细菌类群与浮游植物之间存在潜在的相互作用。
