Cd2+对紫球藻生长及光化学活性的影响

以紫球藻(Porphyridium purpureum)为供试材料, 研究了5个不同浓度的Cd2+对紫球藻的细胞密度、叶绿素a含量、藻红蛋白含量及ATP含量的影响, 以及对紫球藻的最大光量子产额(F_v/F_m)、实际光量子产额(YII)、相对电子传递效率(ETR)及非光化学淬灭(NPQ)的影响, 探讨了各荧光参数在不同浓度的Cd2+胁迫下的变化规律。研究结果表明, 在Cd2+胁迫的6d内, 紫球藻的生长速度显著下降, 且Cd2+的浓度越高, 生长速度下降越快; Cd2+胁迫显著的减少叶绿素a、藻红蛋白及ATP含量, 且浓度越高, 减少的幅度越大; 在Cd2+浓度低于200 μmol/L时, 紫球藻的叶绿素荧光参数F_v/F_m、YII及ETR呈现先下降后上升的趋势,而且随着胁迫时间的延长, 下降幅度逐步增大; NPQ在低浓度下(<200 μmol/L)呈现显著上升趋势, 高浓度下(>500 μmol/L)呈现显著下降趋势。因此, 水体中浓度超过50 μmol/L的Cd2+就会显著影响紫球藻的生长及光化学活性, 水生环境中不断累积的Cd2+将会对紫球藻的生态平衡产生影响。

EFFECTS OF CD2+ STRESS ON THE GROWTH AND PHOTOCHEMICAL ACTIVITY OF PORPHYRIDIUM PURPUREUM

This study investigated the effects of Cd2+ on the biomass, chlorophyll a content, phycoerythrin content and ATP content, the maximum quantum yield of PSII (F_v/F_m), the effective photochemical yield of PSII (YII), the relative electron transfer rate (ETR) and non-photochemical fluorescence of quenching (NPQ) of the Porphyridium purpureum. The results showed that the growth rate of P. purpureum decreased significantly by the stress of Cd2+ in a dosage-dependent pattern. The content of chlorophyll a, phycoerythrin and ATP decreased significantly by Cd2+ stress with a dose-dependent way. The chlorophyll fluorescence parameters (F_v/F_m, YII and ETR) under Cd2+ stress were significantly lower than those of the control groups and decreased rapidly with increased Cd2+ concentration. NPQ value increased significantly at low Cd2+ (<200 μmol/L) and decreased significantly at high Cd2+ (>500 μmol/L). Therefore, the gorwth and phtochemical activities ofPorphyridium purpureum would be significantly affected by the concentration of the Cd2+ above 5 μmol/L and the accumulation of Cd2+ would have an impact on the ecological balance of the Porphyridium purpureum in aquatic environment.