The Toxicity Effect Of Three Quinolone Antibiotics On Scenedesmus Obliquus

Hydrochloric acid enrofloxacin (ENFX), ciprofloxacin hydrochloride (CPFX) and ofloxacin (OFLX) are antibiotics which commonly used in aquaculture. They not only act on target organisms, but also on the other non-target organisms in quatic ecosystems,and affect their growth and physiology. In this study, Scenedesmus obliquus is experimental organism. The toxic effects of different concentrations of ENFX (0,24,48,80,96,120 mg/L),CPFX(0,14.6,29.2,43.8,73,109.5 mg/L) and OFLX (0,22,44,66,112,168 mg/L) on Scenedesmus obliquus were studied in present study.The results showed that:To Scenedesmus obliquus , all of the three antibiotics were low-toxic.The 96h EC50 of ENFX, CPFX, and OFLX were 59.44mg.L-1, 51.71mg.L-1, and 134.07mg.L-1 respectively.The security concentrations of them were 5.94mg.L-1, 5.17 mg. L-1 and 13.41mg.L-1,respectively.Exposured to ENFX, CPFX and OFLX ,the photosynthetic pigment content of Scenedesmus obliquus decreased, and the content of chlorophyll a were much higher than that of chlorophyll b and carotenoids.Treated with ENFX , the soluble protein content of Scenedesmus obliquus increased and then decreased, whereas with CPFX and OFLX, decreased, and the range of CPFX treatment to reduce more.Exposured to ENFX, CPFX and OFLX,the superoxide anion (O2-) production rates increased with the concentration accelerating the production rate and high concentration much higher than the lower concentrations. Treated with lower concentrations of the three quinolone antibiotics , the contents of MDA had a minor change , while with high concentration, changed significantly. Exposured to ENFX and CPFX, the activity of SOD increased with the concentration of treatment, while to OFLX, remained active in all concentrations.Exposured to ENFX, CPFX, and OFLX,the contents of proline similar variation. Compared with the control group,the contents of proline changed little in the low concentration group, or even reduced, while in the high concentration group, then increased rapidly, a large number of accumulation.