title: Response of microcystis to copper stress: do phenotypes of microcystis make a difference in stress tolerance?
abstract: To elucidate the role of phenotype in stress-tolerant bloom-forming cyanobacterium Microcystis, two phenotypes of M. aeruginosa - unicellular and colonial strains were selected to investigate how they responded to copper stress. Flow cytometry (FCM) examination indicated that the percents of viable cells in unicellular and colonial Microcystis were 1.92-2.83% and 72.3-97.51%, respectively, under 0.25 mgl(-1) copper sulfate treatment for 24h. Upon exposure to 0.25 mgl(-1) copper sulfate, the activities of antioxidative enzyme, such as superoxide dismutase (SOD) and catalase (CAT), were significantly increased in colonial Microcystis compared to unicellular Microcystis. Meanwhile, the values of the photosynthetic parameters (F(v)/F(m), ETR(max), and oxygen evolution rate) decreased more rapidly in unicellular Microcystis than in colonial Microcystis. The results indicate that colonial Microcystis has a higher endurance to copper than unicellular Microcystis. This suggests that the efficient treatment concentration of copper sulfate as algaecides will be dependent on the phenotypes of Microcystis.
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, PR China.
authors.forename: Zhong-Xing
authors.initials: ZX
authors.lastname: Wu
authors.forename: Nan-Qin
authors.initials: NQ
authors.lastname: Gan
authors.forename: Qun
authors.initials: Q
authors.lastname: Huang
authors.forename: Li-Rong
authors.initials: LR
authors.lastname: Song
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D019327:Copper Sulfate / Q000633:toxicity*; D003470:Culture Media; D004579:Electron Transport / Q000187:drug effects / Q000502:physiology; D005434:Flow Cytometry / Q000379:methods; D005453:Fluorescence; D046931:Microcystis / Q000187:drug effects* / Q000502:physiology; D018384:Oxidative Stress / Q000502:physiology; D010641:Phenotype; D010788:Photosynthesis / Q000502:physiology; D013482:Superoxide Dismutase / Q000378:metabolism; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D003470:Culture Media; D014874:Water Pollutants, Chemical; D002734:Chlorophyll; D002374:Catalase; D013482:Superoxide Dismutase; D019327:Copper Sulfate; D000077194:Chlorophyll A