集胞藻6803对Pb^(2+)胁迫的生理生化响应

Physiological and biochemical responses of Synechocystis sp. PCC 6803 to stress of Pb^(2+)

为探索藻类对Pb2+胁迫的生理生化响应,首次以集胞藻6803(Synechocystis sp.PCC 6803)为材料,以细胞密度、叶绿素a、可溶性糖、MDA含量及SOD活性为指标,研究Pb2+胁迫下集胞藻的生理生化响应。结果表明,高浓度Pb(NO3)2(>100 mg·L-1)严重抑制集胞藻的生长及叶绿素a的合成,但低浓度Pb(NO3)2(<50 mg·L-1)对其没有明显影响(P>0.05)。而Pb(NO3)2对集胞藻中糖类物质含量的影响不同,尽管50 mg·L-1的Pb(NO3)2对集胞藻生长的抑制作用不明显,但可显著抑制集胞藻中糖类物质的合成(P<0.05)。此外,随着Pb(NO3)2浓度的升高,细胞中MDA含量和SOD活力显著增加,表明细胞中活性氧自由基过量积累,将破坏集胞藻的细胞膜结构与功能,使细胞遭受严重损伤。

In this study, the changes of cell density, contents of chlorophyll a, soluble carbohyd- rate and malondialdehyde （MDA）, and the activity of superoxide dismutase （SOD） in Synechocystis sp. PCC 6803 were analyzed to exploit the physiological and biochemical responses of algae to the stress of Pb2＋. The results showed that high concentration of Pb（NO3）2 （〉100 mg-L-1） had a significant inhibition effects on the growth and chlorophyll a content of Synechocystis sp. PCC 6803, but low concentration of Pb（NO3）2 （〈50 mg-L-1） did not present remarkable inhibition effects （P〉0.05）. However, the synthesis of soluble carbohydrate was restrained by Pb（NO3）2 of 50 mg- L1 （P〈0.05）. In addition, MDA content and SOD activity were enhanced with the increase of Pb（NO3）2 concentrations, showing that excessive accumulation of reactive oxygen species （ROS） damaged the structure and function of algal cell membrane. Therefore, the algal cell suffered serious injuryed under the stress of Pb2＋.