Department of Environmental Science, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
Department of Biology, Aarhus University, Ole Worms Allé 1, 8000 Aarhus C, Denmark; WATEC, Centre for Water Technology, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark.
Harmful Algae. 2024 Jan;131:102549. doi: 10.1016/j.hal.2023.102549. Epub 2023 Nov 27.
Cyanobacterial blooms releasing harmful cyanotoxins, such as microcystin (MC) and cylindrospermopsin (CYN), are prominent threats to human and animal health. Constructed wetlands (CW) may be a nature-based solution for bioremediation of lake surface water containing cyanotoxins, due to its low-cost requirement of infrastructure and environmentally friendly operation. There is recent evidence that microcystin-LR (MC-LR) can efficiently be removed in CW microcosms where CYN degradation in CW is unknown. Likewise, the mechanistic background regarding cyanotoxins transformation in CW is not yet elucidated. In the present study, the objective was to compare MC-LR and CYN degradation efficiencies by two similar microbial communities obtained from CW mesocosms, by two different experiments setup: 1) in vitro batch experiment in serum bottles with an introduced CW community, and 2) degradation in CW mesocosms. In experiment 1) MC-LR and CYN were spiked at 100 µg L and in experiment 2) 200 µg L were spiked. Results showed that MC-LR was degraded to ≤1 µg L within seven days in both experiments. However, with a markedly higher degradation rate constant in the CW mesocosms (0.18 day and 0.75 day, respectively). No CYN removal was detected in the in vitro incubations, whereas around 50 % of the spiked CYN was removed in the CW mesocosms. The microbial community responded markedly to the cyanotoxin treatment, with the most prominent increase of bacteria affiliated with Methylophilaceae (order: Methylophilales, phylum: Proteobacteria). The results strongly indicate that CWs can develop an active microbial community capable of efficient removal of MC-LR and CYN. However, the CW operational conditions need to be optimized to achieve a full CYN degradation. To the best of our knowledge, this study is the first to report the ability of CW mesocosms to degrade CYN.
产毒蓝藻水华释放出有害的蓝藻毒素，如微囊藻毒素（MC）和节球藻毒素（CYN），对人类和动物健康构成了显著威胁。由于构建湿地（CW）的基础设施成本要求低且对环境友好，因此它可能是一种用于含蓝藻毒素的湖泊地表水生物修复的基于自然的解决方案。有最近的证据表明，微囊藻毒素-LR（MC-LR）可以在 CW 微宇宙中有效去除，而 CW 中 CYN 的降解情况尚不清楚。同样，CW 中蓝藻毒素转化的机制背景也尚未阐明。在本研究中，目的是比较从 CW 中培养的两个相似微生物群落中获得的 MC-LR 和 CYN 降解效率，通过两个不同的实验设置：1）在血清瓶中的体外分批实验，引入 CW 群落，和 2）CW 中培养的降解。在实验 1）中，MC-LR 和 CYN 以 100 µg L 的浓度被加入，而在实验 2）中，以 200 µg L 的浓度被加入。结果表明，在两个实验中，MC-LR 在七天内降解至 ≤1 µg L。然而，在 CW 中培养的降解率常数明显更高（分别为 0.18 天和 0.75 天）。在体外孵育中未检测到 CYN 的去除，而在 CW 中培养中，大约 50%的加入的 CYN 被去除。微生物群落对蓝藻毒素处理反应明显，与甲基杆菌科（目：甲基单胞菌目，门：变形菌门）相关的细菌数量明显增加。结果强烈表明，CW 可以形成一个能够有效去除 MC-LR 和 CYN 的活跃微生物群落。然而，需要优化 CW 的运行条件，以实现完全的 CYN 降解。据我们所知，这项研究首次报道了 CW 中培养的降解 CYN 的能力。
