title: Response of the cyanobacterium Microcystis flos-aquae to levofloxacin.
abstract: The effects of levofloxacin (LEV) on Microcystis flos-aquae and its mechanism were investigated by determining the responses of some parameters of M. flos-aquae to LEV stress, including growth inhibition ratio, chlorophyll a content, superoxide dismutase (SOD) and catalase (CAT) activities, malondialdehyde (MDA) content, F v/F 0 and F v/F m, etc. The results indicated that LEV at 0.001-0.1 μg L(-1) could stimulate the growth of M. flos-aquae and increase the chlorophyll a content but did not induce a significant increase in the activity of antioxidant enzymes (SOD and CAT) and the content of MDA. When the LEV concentration exceeds 10 μg L(-1), the growth of M. flos-aquae could be significantly inhibited (the highest inhibition ratio can be up to 88.38 % at 100 μg L(-1)) and chlorophyll a content, SOD and CAT activities, and MDA content also significantly decreased in a concentration-dependent manner, indicating that high concentrations of LEV caused a severe oxidative stress on algal cells, resulting in a large number of reactive oxygen species produced in algal cells and thereby inhibiting the growth of algae. At the same time, the F v/F m and F v/F 0 values of M. flos-aquae decreased significantly with both exposure time and increasing test concentration of LEV, showing that the process of photosynthesis was inhibited.
authors.affiliation: Department of Environmental Science and Engineering, College of Chemical Engineering, Huaqiao University, Xiamen, 361021, Fujian, People's Republic of China.
authors.forename: Jinjin
authors.initials: J
authors.lastname: Wan
authors.forename: Peiyong
authors.initials: P
authors.lastname: Guo
authors.forename: Shengxiang
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000900:Anti-Bacterial Agents / Q000633:toxicity*; D002374:Catalase / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D064704:Levofloxacin / Q000633:toxicity*; D008315:Malondialdehyde / Q000378:metabolism; D046931:Microcystis / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D013482:Superoxide Dismutase / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000900:Anti-Bacterial Agents; D014874:Water Pollutants, Chemical; D002734:Chlorophyll; D008315:Malondialdehyde; D064704:Levofloxacin; D002374:Catalase; D013482:Superoxide Dismutase; D000077194:Chlorophyll A