Monitoring toxigenic cyanobacteria in freshwaters is of great importance due to the adverse health impacts on humans and aquatic organisms. Here we studied cyanobacterial occurrence and biodiversity in a drinking water reservoir in Tehran province, Iran. In total, nine different species representing three orders of Synechococcales, Oscillatoriales and Nostocales were isolated and classified into six families and seven genera ranging from 92.3% to 99.0% similarities in their partial 16S rDNA with GenBank sequences. The cultures were analyzed for cyanotoxins production by the Artemia salina bioassay, ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and also screened for the presence of marker genes involved in toxins production. Ethyl acetate extracts of three strains showed more than 50% mortality on A. salina larvae after 24 h at a concentration of 500 µg/ml. Production of at least one of the cyanotoxins, microcystin (MC), cylindrospermopsin (CYN) and anatoxin-a (ATX-a), was detected in 6 of the strains. Seven MC variants with a total concentration of 130.6 ng/mg of biomass dry weight were detected for the strain Phormidium sp. UTMC6001 and molecular screening of the mcyE gene also confirmed the presence of this biomarker in its genome. Our study also revealed the production of CYN in a novel picocyanobacterial strain Cyanobium sp. UTMC6007 at 1.0 ng/mg of biomass dry weight. Considering the limited information on freshwater toxic cyanobacteria taxonomy in the Middle East, these findings will expand our knowledge and consequently aid in development of new water management policies in future.

由于对人类和水生生物的健康不利，监测淡水中的产毒蓝藻非常重要。在这里，我们研究了伊朗德黑兰省饮用水水库中蓝藻的发生和生物多样性。总共分离出代表聚球目、Oscillatoriales和Nostocales三个目的 9 个不同物种，并将其分为六个科和七个属，其部分16S rDNA与 GenBank 序列的相似性为 92.3% 至 99.0% 。通过卤虫分析培养物产生的蓝藻毒素生物测定法、超高效液相色谱-串联质谱法 (UPLC-MS/MS)，还筛选了参与毒素生产的标记基因的存在。三种菌株的乙酸乙酯提取物在浓度为 500 µg/ml 的情况下，在 24 小时后对A. salina幼虫的死亡率超过 50% 。在 6 个菌株中检测到至少一种蓝藻毒素、微囊藻毒素 (MC)、柱状藻蛋白 (CYN) 和 anatoxin-a (ATX-a) 的产生。对于Phormidium sp.菌株，检测到 7 个 MC 变体，总浓度为 130.6 ng/mg 生物质干重。UTMC6001和的分子筛选mcyE基因还证实了该生物标志物在其基因组中的存在。我们的研究还揭示了在新型微蓝细菌菌株Cyanobium sp. 中产生CYN。UTMC6007 为 1.0 ng/mg 生物质干重。考虑到中东淡水有毒蓝藻分类的信息有限，这些发现将扩大我们的知识，从而有助于未来制定新的水管理政策。