Study on the Toxic Effect of Three Fluoroquinolone Antibiotics on Freshwater Microalgae
The abuse of antibiotics and their derivatives from industrial and agricultural production and human life leads to serious environmental pollution.In this study,the representative fluoroquinolone antibiotics with high detection frequency and ecological risks in aquatic environments such as ofloxacin(OFL),ciprofloxacin(CIP),and norfloxacin(NOR),were selected as the research subjects and the typical algal blooms,and Microcystis aeruginosa and Scenedesmus obliquus,was selected as the test organism.The potential toxic effects and mechanisms of quinolone antibiotics on freshwater microalgae were compre-hensively analyzed through changes in algal cell density,chlorophyll a,and antioxidant stress levels.The results showed that exposure to typical fluoroquinolones significantly inhibited the growth of Microcystis aeruginosa.Specifically,the algal density of each antibiotic treatment group decreased by 1～2 orders of magnitude,with an inhibition rate up to 99.37％.In addition,the concentration of chlorophyll a sharply decreases until it reaches below the detection limit.Exposure of fluoroquinolone antibiotics can induce the production of a large amount of reactive oxygen species(ROS)in algae cells,leading to lipid peroxi-dation.After exposure to Microcystis aeruginosa,the superoxide dismutase(SOD)significantly increased while malondialde-hyde(MDA)obviously decreased compared with the control group(P≤0.01).Exposure to fluoroquinolone antibiotics has a promoting effect on Scenedesmus obliquus,where the algal density increases with the increase of ciprofloxacin concentra-tion.The fluctuation level of SOD in the treatment group shows little difference with the control group,however,MDA content in the treatment group was significantly higher than that in the control group(P≤0.05).At the same time,although Scenedesmus obliquus was subjected to certain oxidative damage,its tolerance was higher than that of Microcystis aeruginosa.By experimental comparison,or different types of algae cells,the tolerance of Scenedesmus obliquus to fluoroquinolone antibi-otics is higher than that of Microcystis aeruginosa.At the same concentration,Scenedesmus obliquus can adapt to the environ-ment through its own regulation,while Microcystis aeruginosa is inhibited or even died.Therefore,the exploration of the toxic effects of the same single antibiotic on different algal cells such as blue-green algae and green algae at the same concentration has important reference value.
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维普
