Food web biomagnification of the neurotoxin β-N-methylamino-L-alanine in a diatom-dominated marine ecosystem in China

The neurotoxin β-N-methylamino-L-alanine (BMAA) reported in some cyanobacteria and eukaryote microalgae is.a cause of concern due to its potential risk of human neurodegenerative diseases. Here, BMAA distribution in.phytoplankton, zooplankton, and other marine organisms was investigated in Jiaozhou Bay, China, a diatomdominated.marine ecosystem, during four seasons in 2019. Results showed that BMAA was biomagnified in.the food web from phytoplankton to higher trophic levels. Trophic magnification factors (TMFs) for zooplankton,.bivalve mollusks, carnivorous crustaceans and carnivorous gastropod mollusks were ca. 4.58, 30.1, 42.5, and.74.4, respectively. Putative identification of β-amino-N-methylalanine (BAMA), an isomer of BMAA, was.frequently detected in phytoplankton samples. A total of 56 diatom strains of the genera Pseudo-nitzschia, Thalassiosira,.Chaetoceros, Planktoniella, and Minidiscus isolated from the Chinese coast were cultured in the laboratory,.among which 21 strains contained BMAA mainly in precipitated bound form at toxin concentrations.ranging from 0.11 to 3.95 μg/g dry weight. Only 2,4-diaminobutyric acid (DAB) but not BMAA or BAMA was.detected in seven species of bacteria isolated from the gut of gastropod Neverita didyma, suggesting that this.benthic vector of BMAA may have accumulated this compound via trophic transfer.

在一些蓝藻和真核微藻中发现的神经毒素β -N -甲基氨基 -L -丙氨酸（BMAA）因其对人类神经退行性疾病的潜在风险而备受关注。在此，我们于2019年的四个季节对中国胶州湾（一个以硅藻为主的海洋生态系统）的浮游植物、浮游动物和其他海洋生物中的BMAA分布进行了调查。结果显示，BMAA在从浮游植物到更高营养级的食物网中发生了生物放大。浮游动物、双壳贝类、肉食性甲壳类和肉食性腹足类软体动物的营养放大系数（TMF）分别约为4.58、30.1、42.5和74.4。在浮游植物样本中经常检测到BMAA的异构体β -氨基 -N -甲基丙氨酸（BAMA）的疑似鉴定。从中国沿海分离出的伪菱形藻属、海链藻属、角毛藻属、浮球藻属和小盘藻属的共56株硅藻菌株在实验室中进行了培养，其中21株含有BMAA，主要以沉淀结合形式存在，毒素浓度范围为每克干重0.11至3.95微克。在从腹足类扁玉螺肠道中分离出的7种细菌中，仅检测到2,4 -二氨基丁酸（DAB），未检测到BMAA或BAMA，这表明这种BMAA的底栖载体可能是通过营养传递积累了该化合物。