Institute of Microbiology and Molecular Genetics, University of the Punjab, Lahore, Pakistan.
Department of Biological Sciences, Université de Montréal, Montreal, Canada.
Environ Sci Pollut Res Int. 2024 Apr;31(16):24648-24661. doi: 10.1007/s11356-024-32744-w. Epub 2024 Mar 6.
Cyanobacteria are known to produce diverse secondary metabolites that are toxic to aquatic ecosystems and human health. However, data about the cyanotoxins occurrence and cyanobacterial diversity in Pakistan's drinking water reservoirs is scarce. In this study, we first investigated the presence of microcystin, saxitoxin, and anatoxin in 12 water bodies using an enzyme-linked immunosorbent assay (ELISA). The observed cyanotoxin values for the risk quotient (RQ) determined by ELISA indicated a potential risk for aquatic life and human health. Based on this result, we made a more in-depth investigation with a subset of water bodies (served as major public water sources) to analyze the cyanotoxins dynamics and identify potential producers. We therefore quantified the distribution of 17 cyanotoxins, including 12 microcystin congeners using a high-performance liquid chromatography-high-resolution tandem mass spectrometry/mass spectrometry (HPLC-HRMS/MS). Our results revealed for the first time the co-occurrence of multiple cyanotoxins and the presence of cylindrospermopsin in an artificial reservoir (Rawal Lake) and a semi-saline lake (Kallar Kahar). We also quantified several microcystin congeners in a river (Panjnad) with MC-LR and MC-RR being the most prevalent and abundant. To identify potential cyanotoxin producers, the composition of the cyanobacterial community was characterized by shotgun metagenomics sequencing. Despite the noticeable presence of cyanotoxins, Cyanobacteria were not abundant. Synechococcus was the most abundant cyanobacterial genus found followed by a small amount of Anabaena, Cyanobium, Microcystis, and Dolichospermum. Moreover, when we looked at the cyanotoxins genes coverage, we never found a complete microcystin mcy operon. To our knowledge, this is the first snapshot sampling of water bodies in Pakistan. Our results would not only help to understand the geographical spread of cyanotoxin in Pakistan but would also help to improve cyanotoxin risk assessment strategies by screening a variety of cyanobacterial toxins and confirming that cyanotoxin quantification is not necessarily related to producer abundance.
蓝藻产生多种次生代谢物，这些代谢物对水生生态系统和人类健康具有毒性。然而，有关巴基斯坦饮用水库中蓝藻毒素的存在和蓝藻多样性的数据很少。在这项研究中，我们首先使用酶联免疫吸附测定法（ELISA）调查了 12 个水体中微囊藻毒素、石房蛤毒素和anatoxin 的存在。根据 ELISA 确定的风险商数（RQ）观察到的蓝藻毒素值表明对水生生物和人类健康存在潜在风险。基于这一结果，我们对一组水体（作为主要公共水源）进行了更深入的调查，以分析蓝藻毒素的动态并确定潜在的生产者。因此，我们使用高效液相色谱-高分辨率串联质谱/质谱（HPLC-HRMS/MS）定量了 17 种蓝藻毒素的分布，包括 12 种微囊藻毒素同系物。我们的结果首次揭示了多种蓝藻毒素的共同存在以及在人工水库（Rawal Lake）和半咸水湖（Kallar Kahar）中存在柱孢藻毒素。我们还在一条河流（Panjnad）中定量了几种微囊藻毒素，其中 MC-LR 和 MC-RR 最为普遍和丰富。为了识别潜在的蓝藻毒素生产者，我们通过 shotgun 宏基因组测序对蓝藻细菌群落的组成进行了特征描述。尽管存在明显的蓝藻毒素，但蓝藻的丰度并不高。聚球藻是发现的最丰富的蓝藻属，其次是少量的鱼腥藻、Cyanobium、微囊藻和 Dolichospermum。此外，当我们观察蓝藻毒素基因覆盖率时，我们从未发现完整的微囊藻毒素 mcy 操纵子。据我们所知，这是巴基斯坦水体的首次快照采样。我们的研究结果不仅有助于了解巴基斯坦蓝藻毒素的地理分布，而且有助于通过筛选多种蓝藻毒素并确认蓝藻毒素定量不一定与生产者丰度相关来改进蓝藻毒素风险评估策略。
