摘要
近年来,水环境中的抗生素污染问题日益突出,为了评估四环素(tetracycline,TC)和甲硝唑(metronidazole,MTZ)对于绿藻的生态风险水平,本研究以蛋白核小球藻为经典模式生物,设计生长抑制实验.通过检测不同浓度TC和MTZ胁迫下的藻细胞密度、表面官能团、胞外聚合物以及叶绿素a(chlorophyll a,Chl-a)含量的变化,分析小球藻的生长情况和氧化应激响应.结果表明,高剂量TC组对小球藻的生长抑制作用是高剂量MTZ组的3倍,当藻细胞暴露于15 mg·L-1 TC的7 d后,藻密度的抑制率达84％,Chl-a浓度减少了 87％以上.高浓度的TC,直接破坏细胞壁、膜等结构完整性和通透性.红外光谱仪(FTIR)分析显示,TC组的酰胺Ⅱ带吸收峰完全消失,蛋白质的合成受到高度抑制.50 mg·L-1 MTZ胁迫下,藻密度和Chl-a浓度抑制率分别增长到85％和80％,同时检测到表面官能团的特征峰发生移动,蛋白质合成抑制受到一定干扰.此外,胞外聚合物还受到TC、MTZ浓度变化的不同程度影响.因此可推断出TC和MTZ对小球藻都表现出较为显著的毒性作用,且TC毒性高于 MTZ.
Abstract
In recent years,the problem of antibiotic pollution in the aquatic environment has become increasingly prominent.To assess the ecological risk level of tetracycline(TC)and metronidazole(MTZ)to green algae,Chlo-rella pyrenoidosa was used as a classical model organism to design growth inhibition experiments in this study.The growth and oxidative stress response of Chlorella pyrenoidosa were analyzed by detecting changes in algal cell density,surface functional groups,extracellular polymers,and chlorophyll a content under different concentrations of TC and MTZ stress.The results showed that after seven days of exposure to TC(15 mg·L-1)and MTZ(50 mg·L-1),the inhibition of algal density reached 84％and 85％,respectively,and the concentrations of chlorophyll a(Chl-a)were both reduced by more than 80％.FTIR analysis showed that specific peaks were shifted in both TC and MTZ test groups and the amide Ⅱ band absorption peaks completely disappeared in the TC group.In addition,the extracellular polymers were also affected by the changes in TC and MTZ concentrations to different degrees.The above experimental results showed that TC and MTZ had more significant toxic effects on Chlorella,and the toxicity of TC was higher than that of MTZ.
维普
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