Ocean College, Zhejiang University, Hangzhou, 310058, Zhejiang, China.
College of the Environment and Ecology, Xiamen University, Xiamen, 361102, Fujian, China.
Water Res. 2020 Jun 15;177:115786. doi: 10.1016/j.watres.2020.115786. Epub 2020 Apr 6.
Cyanobacteria blooms and micropollutants (e.g., antibiotics) in source waters are two increasing environmental issues worldwide. This study hypothesized that the coexisting antibiotics may possibly alter the efficiency of water treatment processes through affecting the physiological and biochemical characteristics of cyanobacterial cells. A toxic strain of Microcystis aeruginosa was exposed to the common antibiotic erythromycin (ERY) at environmentally relevant concentrations; then, samples were collected on days 1, 4 and 6 to assess the efficiency of potassium permanganate (KMnO) in cyanobacteria oxidation. The percentage of intact cells remained constant after treatment with 2 mg L KMnO in M. aeruginosa samples dosed with 0-5.0 μg L ERY. Although 6 mg L KMnO could damage cyanobacterial cells, its ability was considerably reduced as the concentrations of ERY increased. KMnO oxidation degraded the intracellular microcystins (MCs) in all of the cyanobacterial samples, even the samples with intact cells, possibly resulting from the stimulation of intracellular reactive oxygen species (ROS). The highest amounts of total MCs remained after oxidation with 2 and 6 mg L KMnO in 0.2 μg L ERY-treated cyanobacterial samples, which may be due to large amounts of MC production. The 5.0 μg L ERY inhibited the growth of cyanobacterial cells and downregulated the expression of the MC synthesis gene (mcyB), which resulted in the lowest amounts of total MCs. However, it led to the highest concentration (4.6 μg L) of extracellular MCs after treatment with 2 mg L KMnO for 300 min. Generally, this study indicates that the effectiveness of KMnO oxidation in cyanobacteria treatment decreased when the concentration of ERY increased. Hence, the possible risks caused by the coexistence of cyanobacteria and antibiotics, such as reduced efficiency of water treatment processes in cyanobacteria inactivation and degradation of the dissolved MCs, need to be taken into account.
蓝藻水华和微污染物（如抗生素）是全球范围内两个日益严重的环境问题。本研究假设共存的抗生素可能通过影响蓝藻细胞的生理生化特性，从而改变水处理工艺的效率。将一种有毒的铜绿微囊藻（Microcystis aeruginosa）暴露于环境相关浓度的常见抗生素红霉素（ERY）中；然后，在第 1、4 和 6 天采集样品，以评估高锰酸钾（KMnO）在蓝藻氧化中的效率。在含有 0-5.0μg/L ERY 的铜绿微囊藻样品中，用 2mg/L KMnO 处理后，完整细胞的百分比保持不变。尽管 6mg/L KMnO 可以破坏蓝藻细胞，但随着 ERY 浓度的增加，其能力显著降低。KMnO 氧化降解了所有蓝藻样品中的细胞内微囊藻毒素（MCs），即使是完整细胞的样品也是如此，这可能是由于细胞内活性氧物质（ROS）的刺激。在含有 0.2μg/L ERY 的蓝藻样品中，用 2 和 6mg/L KMnO 氧化后，总 MCs 的含量最高，这可能是由于大量 MC 产生所致。5.0μg/L ERY 抑制了蓝藻细胞的生长，并下调了 MC 合成基因（mcyB）的表达，导致总 MCs 的含量最低。然而，在用 2mg/L KMnO 处理 300 分钟后，它导致了最高浓度（4.6μg/L）的细胞外 MCs。一般来说，本研究表明，当 ERY 浓度增加时，KMnO 氧化在蓝藻处理中的有效性降低。因此，需要考虑蓝藻和抗生素共存可能带来的风险，例如水处理过程中蓝藻失活效率降低和溶解态 MCs 降解。
