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 (KMnO4) in cyanobacteria oxidation. The percentage of intact cells remained constant after treatment with 2 mg L-1 KMnO4 in M. aeruginosa samples dosed with 0-5.0 μg L-1 ERY. Although 6 mg L-1 KMnO4 could damage cyanobacterial cells, its ability was considerably reduced as the concentrations of ERY increased. KMnO4 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-1 KMnO4 in 0.2 μg L-1 ERY-treated cyanobacterial samples, which may be due to large amounts of MC production. The 5.0 μg L-1 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-1) of extracellular MCs after treatment with 2 mg L-1 KMnO4 for 300 min. Generally, this study indicates that the effectiveness of KMnO4 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.

中文翻译：

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微污染物红霉素对高锰酸钾处理蓝细菌的影响。

蓝藻水华和源水中的微污染物（例如抗生素）是全球范围内两个日益严重的环境问题。这项研究假设，共存的抗生素可能会通过影响蓝细菌细胞的生理和生化特性来改变水处理过程的效率。铜绿微囊藻的毒性菌株以与环境有关的浓度暴露于普通抗生素红霉素（ERY）。然后在第1、4和6天收集样品，以评估高锰酸钾（KMnO4）在蓝细菌氧化中的效率。在用0-5.0μgL-1 ERY注射的铜绿假单胞菌样品中，用2 mg L-1 KMnO4处理后，完整细胞的百分比保持恒定。尽管6 mg L-1 KMnO4可能会损害蓝细菌细胞，随着ERY浓度的增加，其能力大大降低。KMnO4氧化降解了所有蓝细菌样品（甚至是具有完整细胞的样品）中的细胞内微囊藻毒素（MCs），这可能是由于细胞内活性氧（ROS）的刺激所致。在0.2μgL-1 ERY处理的蓝细菌样品中，用2和6 mg L-1 KMnO4氧化后，残留的总MC最高，这可能是由于大量MC产生。5.0μgL-1 ERY抑制了蓝细菌细胞的生长，并下调了MC合成基因（mcyB）的表达，这导致总MC量最低。然而，在用2 mg L-1 KMnO4处理300分钟后，导致细胞外MC的最高浓度（4.6μgL-1）。通常，这项研究表明，当ERY浓度增加时，KMnO4氧化在蓝藻处理中的有效性降低。因此，需要考虑到由蓝细菌和抗生素共存引起的潜在风险，例如蓝细菌灭活中水处理过程效率降低和溶解的MC降解。