铜绿微囊藻对有机毒物菲的生理生态响应研究

选取富营养化湖泊蓝藻水华常见优势种铜绿微囊藻（Microcystis aeruginosa，M. aeruginosa）为研究对象，采用室内暴露培养实验考察多环芳烃（Polycyclic aromatic hydrocarbons，PAHs）化合物菲（Phenanthrene，Phe）对铜绿微囊藻生长及生理特性的影响效应和作用机制。研究结果表明，低浓度Phe（0.05~0.2 mg/L）对铜绿微囊藻细胞生长有不同程度的促进作用，0.2 mg/LPhe促进作用最为显著（P＜0.05）；高浓度Phe（0.5~1.0 mg/L）显著抑制铜绿微囊藻生长（P＜0.05）。铜绿微囊藻典型生理指标细胞光合作用率（Fv/Fm）、超氧化物歧化酶（SOD）、谷氨酰胺还原酶（GR）酶活性以及丙二醛（MDA）含量同步分析结果显示，低浓度Phe通过增强SOD、GR酶活性，降低铜绿微囊藻细胞内MDA含量，提高藻细胞光合作用率，进而促进细胞增殖；高浓度Phe则通过降低SOD、GR酶活性，增加藻细胞内MDA产量，减弱细胞光合作用，从而抑制细胞生长。对不同暴露时刻藻细胞的生长抑制率进行回归分析可得EC50（半抑制浓度）随着污染暴露时间增加而减低，1day EC50为1.27 mg/L，12day EC50降至0.65 mg/L，即高剂量Phe（0.5~1.0 mg/L）对微囊藻细胞生长的抑制作用随时间延长逐渐增强。结合低剂量浓度下Phe对铜〖JP+2〗绿微囊藻生长的促进作用分析，湖泊生态系统Phe污染长期暴露对铜绿微囊藻生长生理特性及优势种的形成和维持具有不可忽视的作用。其中，铜绿微囊藻细胞主要生理指标SOD与GR对Phe污染胁迫反应灵敏，可用作评价PAHs等有机毒物对浮游藻类生理生态影响的生物标记物

Physi Ecological Responses of Microcystis aeruginosa to Phenanthrene Exposure

The physi ecological responses of Microcystis aeruginosa to different concentrations of phenanthrene (Phe) with different exposure time were studied. Results indicated that the growth rates of M. aeruginosa were stimulated under the lower doses of Phe with the range of 005-02 mg/L; compared to the control, the stimulation effects under 02 mg/L Phe was significant (P＜005).Growth rates were significantly inhibited under the higher concentrations of Phe (05-10 mg/L) (P＜005). Potential internal mechanisms were further investigated by analyzing several typical physiological parameters such as the photochemical efficiency (Fv/Fm), superoxide dismutase (SOD), glutathione reductase (GR) and malondialdehyde (MDA). Under the lower exposure concentrations (005-02 mg/L), the associated increase of the enzyme activities of SOD and GR, and the decrement of MDA contents would improve the photosynthesis and stimulate the growth rates.While for the higher exposure concentrations (05-10 mg/L), the growth rates were inhibited mainly by the decrement of SOD activities, GR activities and photosynthesis as well as the increase of MDA contents. The EC50 of Phe (1day EC50 and 12day EC50 were 127 mg/L and 065 mg/L, respectively) on the inhibition of the growth indicated the inhibition increased with the exposure time. Therefore, the development and maintenance of phytoplankton community dominated by M. aeruginosa, would more or less affected by the continuous inputs of Phe. Moreover, such physiological properties as SOD and GR could be used as efficient biomarkers of Phe pollution because of their high sensitivity