ABSTRACT This study describes the first report on saxitoxins (STXs) and anatoxin-a (ANTX-a) production by cyanobacteria in Lithuanian lakes. Seasonal fluctuation patterns for neurotoxins were determined in samples collected from eutrophic lakes during July–September. Strains of Aphanizomenon gracile, A. flos-aquae, Cuspidothrix issatschenkoi, Sphaerospermopsis aphanizomenoides and Anabaenopsis cf. elenkinii were also isolated from the lakes and screened for the occurrence of neurotoxic STXs, ANTX-a and for the cytotoxin cylindrospermopsin (CYN). The highest concentration of STX (up to 1.06 µg l–1 in Lake Jieznas) was detected during July‒August and coincided with a predominance of A. gracile in the phytoplankton. Of the isolated strains, only A. gracile was confirmed to be a producer of STXs by chemical (LC-MS/MS) and genetic (sxtA) methods. Sequencing of the phycocyanin intergenic spacer and flanking regions (cpcBA) revealed that A. gracile formed a genetically homogenous group. Only trace amounts of ANTX-a were detected in field samples (up to 0.31 µg l–1 in Lake Širvys). CYN was detected in neither the bloom samples nor in the isolated strains.

中文翻译：

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立陶宛湖泊蓝藻产生石房蛤毒素和类毒素-a 的首次报告

摘要 本研究描述了立陶宛湖泊蓝藻产生石房蛤毒素 (STX) 和类毒素 a (ANTX-a) 的第一份报告。在 7 月至 9 月期间从富营养化湖泊收集的样本中确定了神经毒素的季节性波动模式。Aphanizomenon gracile、A. flos-aquae、Cuspidothrix issatschenkoi、Sphaerospermopsis aphanizomenoides 和 Anabaenopsis 菌株。elenkinii 也从湖泊中分离出来，并筛选了神经毒性 STX、ANTX-a 和细胞毒素圆柱藻素 (CYN) 的出现。在 7 月至 8 月期间检测到 STX 的最高浓度（在杰兹纳斯湖中高达 1.06 µg l-1），这与浮游植物中 A. gracile 的优势相吻合。在分离的菌株中，只有 A. gracile 通过化学 (LC-MS/MS) 和遗传 (sxtA) 方法被证实是 STX 的生产者。藻蓝蛋白基因间间隔区和侧翼区 (cpcBA) 的测序显示 A. gracile 形成了一个基因同质的群体。在现场样品中仅检测到痕量的 ANTX-a（在 Lake Širvys 中检测到高达 0.31 µg l–1）。CYN 在布卢姆样品和分离菌株中均未检测到。