Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China; University of Chinese Academy of Sciences, Beijing, 100190, China.
National and Local Joint Engineering Research Center of Ecological Treatment Technology for Urban Water Pollution, Zhejiang Provincial Key Lab for Water Environment and Marine Biological Resources Protection, Institute for Eco-Environmental Research of Sanyang Wetland, Wenzhou University, Wenzhou, 325035, China.
Environ Pollut. 2024 May 1;348:123878. doi: 10.1016/j.envpol.2024.123878. Epub 2024 Mar 26.
Addressing notorious and worldwide Microcystis blooms, mechanical algae harvesting is an effective emergency technology for bloom mitigation and removal of nutrient loads in waterbodies. However, the absence of effective methods for removal of cyanobacterial toxins, e.g., microcystins (MCs), poses a challenge to recycle the harvested Microcystis biomass. In this study, we therefore introduced a novel approach, the "captured biomass-MlrA enzymatic MC degradation", by enriching microcystinase A (MlrA) via fermentation and spraying it onto salvaged Microcystis slurry to degrade all MCs. After storing the harvested Microcystis slurry, a rapid release of extracellular MCs occurred within the initial 8 h, reaching a peak concentration of 5.33 μg/mL at 48 h during the composting process. Upon spraying the recombinant MlrA crude extract (about 3.36 U) onto the Microcystis slurry in a ratio of 0.1% (v/v), over 95% of total MCs were degraded within a 24-h period. Importantly, we evaluated the reliability and safety of using MlrA extracts to degrade MCs. Results showed that organic matter/nutrient contents, e.g. soluble proteins, polysaccharides, phycocyanin and carotenoids, were not significantly altered. Furthermore, the addition of MlrA extracts did not significantly change the bacterial community composition and diversity in the Microcystis slurry, indicating that the MlrA extracts did not increase the risk of pathogenic bacteria. Our study provides an effective and promising method for the pre-treatment of harvested Microcystis biomass, highlighting an ecologically sustainable framework for addressing Microcystis blooms.
针对臭名昭著且在全球范围内广泛存在的微囊藻水华问题，机械性藻类收获是一种有效的紧急技术，可以缓解水华并去除水体中的营养负荷。然而，由于缺乏有效的方法来去除蓝藻毒素，例如微囊藻毒素（MCs），这给收获的微囊藻生物质的回收利用带来了挑战。在本研究中，我们通过发酵富集微囊藻酶 A（MlrA），并将其喷洒到回收的微囊藻泥浆上来降解所有 MCs，从而引入了一种新的方法，即“捕获生物质-MlrA 酶促 MC 降解”。在收获的微囊藻泥浆储存后，在堆肥过程中最初的 8 小时内，细胞外 MCs 迅速释放，在 48 小时时达到 5.33μg/mL 的峰值浓度。当将重组 MlrA 粗提物（约 3.36 U）以 0.1%（v/v）的比例喷洒到微囊藻泥浆上时，在 24 小时内超过 95%的总 MCs 被降解。重要的是，我们评估了使用 MlrA 提取物降解 MCs 的可靠性和安全性。结果表明，有机质/营养物含量，例如可溶性蛋白质、多糖、藻蓝蛋白和类胡萝卜素，没有明显变化。此外，添加 MlrA 提取物并没有显著改变微囊藻泥浆中的细菌群落组成和多样性，表明 MlrA 提取物不会增加致病菌的风险。我们的研究为收获的微囊藻生物质的预处理提供了一种有效且有前景的方法，突出了一种生态可持续的解决微囊藻水华的框架。
