Isolation and characterization of a high-efficiency algicidal bacterium Pseudoalteromonas sp. LD-B6 against the harmful alga Noctiluca scintillans

Abstract: The dinoflagellate Noctiluca scintillans is a globally distributed harmful alga that pose a certain threat to marine ecosystems. Recently, isolation of algicidal bacteria is one of a candidate method to prevent and control harmful algae bloom because of its advantages of safety and efficiency. In this study, a strain of algicidal bacterium LD-B6 with high efficiency against N. scintillans was isolated from the coastal waters of Lianyungang, China. 16S rDNA sequence analysis showed that strain LD-B6 belong to genus Pseudoalteromonas. Furthermore, the algicidal effect of LD-B6 lysing N. scintillans was investigated. The results showed that strain LD-B6 had strong algicidal activity against N. scintillans, After 12 h of bacterial culture addition, the algicidal rate reached 90.5% with a 2% final volume rate, and the algicidal activity of LD-B6 was influenced by the density of N. scintillans. In addition, the algicidal bacterium LD-B6 indirectly lysed algae by secreting extracellular compounds, and the algicidal compounds is stable, indicating that it’s not protein. Importantly, strain LD-B6 was broadly specific, showing varying degrees of lysing effects against five of the six algal species tested. In summary, isolated LD-B6 shows potent algicidal capability, providing a candidate algicidal bacterium against N. scintillans blooms.