title: [Effects of algicidal bacterium BS03 (Microbulbifer sp.) on the growth and antioxidant systems of Alexandrium tamarense].
abstract: 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.
  
  
  CONCLUSIONS
  BS03 inhibited the photosynthesis whereas enhanced the lipid peroxidation of the cellular membrane of Alexandrium tamarense, indicating its algicidal activity.
authors.affiliation: Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China. lijun_fu@xmu.edu.cn
authors.forename: Lijun
authors.initials: L
authors.lastname: Fu
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.forename: Chengji
authors.initials: C
authors.lastname: Wu
authors.forename: Tianling
authors.initials: T
authors.lastname: Zheng
mesh_terms: D034241:Alteromonadaceae / Q000254:growth & development / Q000378:metabolism*; D000898:Antibiosis; D000975:Antioxidants / Q000378:metabolism*; D001685:Biological Factors / Q000494:pharmacology*; D002338:Carotenoids / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D017077:Culture Media, Conditioned; D004141:Dinoflagellida / Q000254:growth & development / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D001685:Biological Factors; D017077:Culture Media, Conditioned; D002734:Chlorophyll; D002338:Carotenoids; D053148:Caspase 3; D000077194:Chlorophyll A