溶藻细菌BS03(Microbulbifer sp.)对塔玛亚历山大藻生长及抗氧化系统的影响

Effects of algicidal bacterium BS03(Microbulbifer sp.) on the growth and antioxidant systems of Alexandrium tamarense

【目的】研究溶藻细菌BS03(Microbulbifer sp.)胁迫下塔玛亚历山大藻细胞光合作用、抗氧化酶系统和半胱氨酸蛋白酶3(Caspase-3)变化,探讨溶藻细菌BS03对塔玛亚历山大藻的溶藻机制。【方法】通过0.5%、1.0%、1.5%、2.0%不同终浓度BS03上清液处理藻细胞后12、24、36、48h取样,测定溶藻过程藻细胞光合色素、叶绿素荧光效率、抗氧化酶系统、Caspase酶活性变化。【结果】(1)BS03上清液处理藻细胞后,藻细胞叶绿素a含量和叶绿素荧光Fv/Fm比值随BS03上清液处理时间延长和浓度的增加呈逐渐下降趋势;低浓度处理组藻细胞类胡萝卜素含量上升到一峰值,高于对照组后逐渐回落,而高浓度处理组类胡萝素含量呈下降趋势,低于对照组;(2)藻细胞抗氧化酶保护系统(SOD和CAT)活性随着BS03上清液处理浓度增加而升高,但随着处理时间的延长呈现先上升后下降趋势。藻细胞膜脂过氧化产物MDA积累量随着BS03上清液处理时间延长和处理浓度的增加而显著提高;(3)处理组藻细胞Caspase-3活性显著高于对照组,呈现出类似程序性死亡特征。【结论】BS03的抑藻机理可能是通过抑制藻细胞光合作用,降低抗氧化酶活性、加大膜脂过氧化起到对塔玛亚历山大藻的溶解作用,并呈现出类程序性死亡特征。

[ Objective] We studied the algicidal mechanism of extracellular substances of algicidal bacteria strain BS03 （Microbulbifer sp. ） on photosynthetic characteristics, antioxident enzyme system and cysteine-dependent aspartate specific protease-3 （Caspase-3） of Alexandrium tamarense. [ Methods ] We tested photosynthetic pigments, chlorophyll fluorescence efficiency, antioxidant systems and caspase-3 activity in the algae cells treated with 0.5% , 1.0% , 1.5% and 2.0% BS03 cell-free filtrate after 12, 24, 36 and 48 h. [ Results] （1） The chlorophyll-a and chlorophyll fluorescence efficiency Fv/Fm decreased with the increase of BS03 cell-free filtrate and treatment time. Carotenoids contents of A. tamarense cells treated with low BS03 （0.5% and 1.0% ） cell-free filtrate were higher than the control. （2） Antioxident enzyme activities varied as treatment time and concentration. Malodialdehyde （MDA） contents increased significantly with BS03 cell-free filtrate treatment. （3） Caspase-3 protease activities of algal cells increased by BS03 cell- free filtrate. [ Conclusion ] BS03 inhibited the photosynthesis whereas enhanced the lipid peroxidation of the cellular membrane of Alexandrium tamarense, indicating its algicidal activity.