群体和单细胞微囊藻对短期高光胁迫的生理响应

为了探讨不同形态的微囊藻（Microcystis）对光的耐受能力及其应对机制，研究比较了短期高光强条件下群体微囊藻和单细胞微囊藻的生理响应，结果表明，在高光强胁迫下，群体和单细胞微囊藻的叶绿素含量、最大电子传递速率（ETR_max）均降低，但与单细胞微囊藻相比，群体微囊藻的下降幅度较小；在高光强胁迫下，群体微囊藻的过氧化氢酶（CAT）与超氧化物歧化酶（SOD）的活性均显著增加，而单细胞微囊藻只有CAT活性增加；在短期高光胁迫下，群体微囊藻的死亡率没有显著变化。这些结果表明群体微囊藻比单细胞微囊藻能耐受更高的光强，也暗示了群体微囊藻在野外高光强条件下更具竞争优势。

THE PHYSIOLOGICAL RESPONSE OF COLONIAL AND SINGLE-CELLED FORM OF MICROCYSTIS TO SHORT-TERM HIGH STRESS

Light is one of the important factors for algae growth and product by photosynthesis. This study investigated the physiological response of colonial and single-celled form of Microcystis to light intensity. The results showed that the Chl. a and ETRmax in colonial and single-celled forms of Microcystis were declined by high light intensity with a bigger decrease in single-celled form of Microcystis. The enzyme activities of SOD and CAT in colonial and single-celled form of Microcystis were increased by high light intensity. The colonial form of Microcystis decreased the photooxi-date damage by increasing SOD and CAT activities, while single-celled Microcystis reduced damage through CAT acti-vity only. The mortality rate of colonial form of Microcystis showed no significantly difference by short-term high light intensity. These suggest that colonial form of Microcystis had higher tolerance to high light intensity when compared with single-celled form of Microcystis, explaining that colonial Microcystis are predominate strains in water blooms.