Isolation and identification of three algae-lysing bacteria and their lytic effects on Microcystis aeruginosa

摘要

Three cyanobacterial-lysing heterotrophic bacterial strains (F1, F2 and F3) were isolated from a lake experiencing cyanobacterial bloom with the liquid infection method. According to their morphological, physiological and biochemical characteristics and the results of 16SrDNA sequence analysis, F1, F2 and F3 were identified as strains of Staphylococcus sp. R-25050, Stappia sp. and Microbacterium sp., respectively. After being co-cultured with the axenic cyanobacterium Microcystis aeruginosa 905 for 7 days, strains F1, F2 and F3 exhibitied an inhibition effect on cyanobacterial growth, which was expressed as a reduction in chlorophyll concentration of 96.0%, 94.9% and 84.8%. Autoclaved or filtered bacterial cultures still showed lytic effect on cyanobacterial cells, while centrifuged pellets were less efficient than other fractions. A cell number ratio of 4:1 (bacteria:cyanobacteria) was needed to get a significant lytic activity. Even higher ratio was needed if the LB medium was removed from the cells. These results showed the potential of algae-lysing bacteria as biological control agents for cyanobacterial bloom.