Isolation, identification and characterization of algicidal bacterium BS03 against Alexandrium tamarense
溶藻细菌BS03分离、鉴定及其对塔玛亚历山大藻生长的影响

A bacterial strain, BS03, exhibiting strongest activity against the toxic dinoflagellate, Alexandrium tamatense, was isolated from the Zhangjiang Estuary Mangrove National Natural Reserve, China. Based on 16S rRNA gene sequences and biochemical and morphological characteristics, the strain BS03 was determined to be Microbulbifer sp. on the basis of 99.0% similarity with reference strain sequences from the NCBI. The growth of A. tamatense was strongly suppressed by BS03 in all growth phases. With the strongest algicidal activity noted against harmful algae in the lag stage, the removal rate of A. tamatense reached 98.17% after 96 h. In addition, the initial concentration of the bacterial culture strongly affected the algicidal ability. The higher concentration of the bacterial culture was, the stronger algicidal activity to the A. tamatense. Furthermore, BS03 indirectly attacked A. tamatense by algicidal substances. The molecular weight of algicidal compounds were less than 1 kDa, and heat tolerant and stable in acidic and alkaline conditions. According to our results, we speculated the algicidal compounds could not be proteinaceous, nucleate and polysaccharide. These findings indicated that strain BS03 could be a potential bio-agent for future use in controlling harmful algal blooms.