Wadt Pedro Rebelo, Mafra Luiz Laureno, Dos Santos Tavares Camila Prestes, Fernandes Luciano Felício, de Oliveira Proença Luís Antonio
Centro de Estudos do Mar, Universidade Federal do Paraná, P.O. Box 61, Pontal do Paraná, PR, 83255-976, Brazil.
Departamento de Botânica, Universidade Federal do Paraná, P.O. Box 19031, Curitiba, PR, 81531-990, Brazil.
Environ Monit Assess. 2017 Nov 9;189(12):621. doi: 10.1007/s10661-017-6301-z.
Pseudo-nitzschia is a diatom genus capable of producing the neurotoxin domoic acid (DA), which has been related to mortalities of marine vertebrates, and the amnesic shellfish poisoning (ASP) in human consumers of contaminated bivalves. This study reports DA production among Pseudo-nitzschia strains isolated from shellfish farming areas in southern Brazil. Twenty-seven cultures of potentially toxigenic Pseudo-nitzschia species were established. Growth, stepped-chain formation, and DA production were evaluated in static, intermittently illuminated (12:12 photoperiod) batch cultures for 12 selected strains, and under continuous light and/or turbulence for a single Pseudo-nitzschia calliantha strain. Growth rate ranged from 0.16 to 0.39 day among the 12 strains. Only P. calliantha and P. cf. multiseries yielded detectable levels of intracellular DA, reaching up to 0.054 fg cell in late exponential and 0.15 pg cell in early stationary phase, respectively. Continuous light impaired cell growth, and turbulence enhanced step-chain formation by threefold during exponential growth phase, but no DA production was detected under both conditions. The effect of turbulence on chain formation should be further evaluated in the field, once particle size is expected to affect the ingestion of toxic cells and thus toxin accumulation by certain DA vectors. The low cell toxicity revealed herein under laboratory conditions is in accordance with the low frequency of DA contamination episodes in south Brazilian waters. Nevertheless, monitoring of Pseudo-nitzschia abundance and DA presence in farming areas is continuously required to assure the quality of local shellfish products.
拟菱形藻是一种能够产生神经毒素软骨藻酸（DA）的硅藻属，该毒素与海洋脊椎动物的死亡以及食用受污染双壳贝类的人类消费者发生的失忆性贝类中毒（ASP）有关。本研究报告了从巴西南部贝类养殖区分离出的拟菱形藻菌株中DA的产生情况。建立了27种具有潜在产毒能力的拟菱形藻物种的培养物。对12个选定菌株在静态、间歇光照（12:12光周期）分批培养中评估其生长、阶梯链形成和DA产生情况，并对单个拟菱形藻卡利安塔菌株在连续光照和/或湍流条件下进行评估。12个菌株的生长速率在0.16至0.39天之间。只有卡利安塔拟菱形藻和多列拟菱形藻（疑似种）产生了可检测水平的细胞内DA，在指数生长后期分别达到0.054 fg/细胞，在稳定期早期达到0.15 pg/细胞。连续光照会损害细胞生长，湍流在指数生长期使阶梯链形成增加了三倍，但在这两种条件下均未检测到DA产生。一旦预计颗粒大小会影响有毒细胞的摄取以及某些DA载体的毒素积累，就应在现场进一步评估湍流对链形成的影响。本文在实验室条件下揭示的低细胞毒性与巴西南部水域DA污染事件的低频率一致。尽管如此，仍需要持续监测养殖区拟菱形藻的丰度和DA的存在情况，以确保当地贝类产品的质量。
