溶藻细菌HSY-03对赤潮异弯藻抗氧化系统的影响

Effects of Algicidal Bacterium HSY-03 on Antioxidant Defense System of Heterosigma akashiwo

为研究溶藻细菌HSY-03(Bacillus sp.)对赤潮异弯藻的溶藻机制,采用不同浓度HSY-03无菌上清液处理赤潮异弯藻藻细胞,测定藻细胞光合色素含量、叶绿素荧光效率、细胞内部活性氧(ROS)水平和抗氧化系统活性变化。结果表明,HSY-03无菌上清液作用24 h之后,赤潮异弯藻叶绿素a含量、类胡萝卜素含量和最大光化学效率(F v/F m值)均快速下降,表明藻细胞光合作用受到抑制;处理2 h后ROS含量即上升,至6 h后逐渐下降;处理12 h膜脂化过氧化产物丙二醛(MDA)含量上升,至48 h达到峰值,表明藻细胞内部氧化损伤严重;藻细胞内抗氧化系统响应被激发,抗氧化酶系统超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性不同程度上升,以清除细胞内部ROS。非酶促抗氧化系统谷胱甘肽(GSH)和抗坏血酸(AsA)含量上升,二者协同作用清除ROS。这表明,HSY-03上清液可能通过影响光合作用和作用于藻体的膜结构,引起细胞氧化损伤,最终导致藻细胞死亡。研究结果表明,HSY-03可以作为一种长期环境友好型生物因子有效防治赤潮异弯藻。

In order toreveal the algicidal mechanism of bacteria HSY-03(Bacillus sp.)on harmful algae Heterosigma akashiwo,the photosynthetic pigments contents,chlorophyll fluorescence efficiency,photosynthetic parameters,reactive oxygen species(ROS)level and antioxidant systems activities in the algae cells treated with HSY-03 cell-free filtrate were measured.The results showed that chlorophyll a,carotenoids contents and chlorophyll a fluorescence F v/F m decreased rapidly after 24 h treatment by HSY-03 cell-free filtrate,indicating that bacterium HSY-03 inhibited the photosynthesis of the algae.The ROS contents increased after 2 h cell-free filtrate treatment then gradually decreased after 6 h treatment.Responses of antioxidant system of algae were stimulated.The activities of antioxidant enzymes such as superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD)increased in different degrees to clear ROS in the algae cells.The activities of non-enzymatic antioxidant systems such as glutathione(GSH)and ascorbic acid(ASA)also increased,and both of them cooperated to eliminate ROS.These results suggested that the algicidal bacterium HSY-03 might affect the photosynthesis and the membrane structure of algae,cause cell oxidative damage,and eventually lead to cell death.Therefore,applying HSY-03 as a long-term and environmentally friendly bio-agent to control the harmful blooms of Heterosigma akashiwo,would be effective and promising.