The neurotoxic secondary metabolite β-N-methylamino-L-alanine (BMAA) and its structural isomer 2,4-diaminobutyric acid (DAB) are known to be produced by various phytoplankton groups. Despite the worldwide spread of these toxin producers, no obvious role and function of BMAA and DAB in diatoms have been identified. Here, we investigated the effects of biotic factors, i.e., predators and competitors, as possible causes of BMAA and/or DAB regulation in the two diatom species Phaeodactylum tricornutum and Thalassiosira pseudonana. DAB was specifically regulated in T. pseudonana by the presence of predators and competitors. The effects of DAB on both diatoms as competitors and on the copepod Tigriopus sp. as predator at individual and at population levels were examined. The toxic effects of DAB on the growth of T. pseudonana and the population of Tigriopus sp. were significant. The effect of DAB as a defensive secondary metabolite is assumed to be environmentally relevant depending on the number of the copepods. The results show a potential function of DAB that can play an important role in defense mechanisms of T. pseudonana.

已知具有神经毒性的次生代谢物 β-N-甲基氨基-L-丙氨酸 (BMAA) 及其结构异构体 2,4-二氨基丁酸 (DAB) 由各种浮游植物群产生。尽管这些毒素生产者在全球范围内传播，但尚未确定 BMAA 和 DAB 在硅藻中的明显作用和功能。在这里，我们研究了生物因素的影响，即捕食者和竞争者，它们可能是两种硅藻物种三角褐指藻和拟南海藻中BMAA和/或 DAB 调节的可能原因。DAB 在T. pseudonana中受到捕食者和竞争者的特别调节。DAB对作为竞争者的硅藻和桡足类Tigriopus的影响sp。在个体和种群水平上作为捕食者进行了检查。DAB对T. pseudonana和Tigriopus sp的生长的毒性作用。意义重大。假定 DAB 作为防御性次生代谢物的作用与环境相关，具体取决于桡足类的数量。结果表明DAB的潜在功能可以在假单胞菌的防御机制中发挥重要作用。