环境浓度下的混合抗生素对普通小球藻的联合毒性

The Joint Toxicity of Mixed Antibiotics on Chlorella vulgaris at Normal Environmental Concentration

近年来,抗生素已成为一类备受关注的新型环境污染物。为了探究这类化合物对各类生物的毒性效应,本实验以红霉素(ERY)、恩诺沙星(ENR)、磺胺甲恶唑(SMX)这3种常见的抗生素作为代表,研究其单独作用和两两联合作用对普通小球藻的生长、蛋白合成及丙二醛(MDA)含量的影响。结果表明:ERY、ENR和SMX对小球藻的96h-EC50分别为85.7、124.5和1672.7μg·L^-1,且3种抗生素两两联合时对小球藻的毒性作用类型均为协同作用。此外,当暴露于环境浓度的抗生素时,无论是单独加药还是联合加药,除ERY处理组的小球藻的蛋白合成被轻微抑制外,其他各处理组的蛋白含量与对照组相比,均展现出低剂量刺激效应。对于MDA产量,ENR处理组的MDA含量与对照组无显著差异,其他各处理组均高于对照组;故环境浓度下的ENR并没有对小球藻造成明显的氧化损伤,而其他2种抗生素则对小球藻造成了氧化损伤。该研究为低浓度混合抗生素在淡水环境中联合暴露的生态风险评估提供了科学依据。

Antibiotics have been widely concerned as a type of emerging environmental pollutants in recent years. In this work, three common antibiotics, erythromycin (ERY), enrofloxacin (ENR), and sulfamethoxazole (SMX), were selected as representatives to explore the toxic effects of antibiotics on various organisms. The growth situation, contents of protein, and malondialdehyde (MDA) of Chlorella vulgaris exposed to these three antibiotics were investigated, alone and in pairs systems. The obtained results showed that the 96 h-EC50 of ERY, ENR, and SMX to C. vulgaris was 85.7, 124.5, and 1 672.7 μ g ·L^-1 , respectively. Moreover, when C. vulgaris was exposed to the antibiotics combined in pairs, the joint toxicity of the mixtures showed synergistic effect. In addition, the protein synthesis of C. vulgaris exposed at environmental concentration was slightly inhibited in the ERY-treatment while the other treatments exhibited low-dose stimulatory effects. The MDA content in the ENR-treatment was not significantly different from that in the control, but those in other treatments were all higher than that in the control. From the result of MDA determination, we can make the conclusion that ENR did not induce significant oxidative damage to C. vulgaris at the environmental concentration, while the other two antibiotics induced oxidative damage to C. vulgaris . The results provide scientific basis for the ecological risk assessment of combined exposure of low-level mixed antibiotics in freshwater environments.