Abstract：
Toxic cyanobacterial blooms present a substantial risk to public health due to the production of secondary metabolites, notably microcystins (MCs). Microcystin-LR (MC-LR) is the most prevalent and toxic variant in freshwater. MCs resist conventional water treatment methods, persistently impacting water quality. This study focused on an oligohaline shallow lagoon historically affected by MC-producing cyanobacteria, aiming to identify bacteria capable of degrading MC and investigating the influence of environmental factors on this process. While isolated strains did not exhibit MC degradation, microbial assemblages directly sourced from lagoon water removed MC-LR within seven days at 25 ºC and pH 8.0. The associated bacterial community demonstrated an increased abundance of bacterial taxa assigned to Methylophilales, and also Rhodospirillales and Rhodocyclales to a lesser extent. However, elevated atmospheric temperatures (45 ºC) and acidification (pH 5.0 and 3.0) hindered MC-LR removal, indicating that extreme environmental changes could contribute to prolonged MC persistence in the water column. This study highlights the importance of considering environmental conditions in order to develop strategies to mitigate cyanotoxin contamination in aquatic ecosystems.
摘要：
由于次生代谢产物的产生，有毒的蓝藻水华对公众健康构成重大风险，特别是微囊藻毒素（MC）。微囊藻毒素-LR（MC-LR）是淡水中最普遍和最有毒的变体。MC抵抗传统的水处理方法，持续影响水质。这项研究的重点是历史上受MC产生的蓝细菌影响的低盐浅层泻湖，旨在鉴定能够降解MC的细菌，并研究环境因素对此过程的影响。虽然分离的菌株没有表现出MC降解，直接来自泻湖水的微生物组合在25ºC和pH8.0的7天内去除MC-LR。相关的细菌群落表明，分配给嗜甲基的细菌分类群的丰度增加，以及在较小程度上的红螺旋藻和红螺旋藻。然而,升高的大气温度（45ºC）和酸化（pH5.0和3.0）阻碍了MC-LR的去除，表明极端的环境变化可能导致水柱中MC的持久性延长。这项研究强调了考虑环境条件以制定减轻水生生态系统中氰基毒素污染的策略的重要性。
