Diverse algicidal bacteria associated with harmful bloom-forming Karenia mikimotoi in estuarine soil and seawater

摘要

Algicidal bacteria associated withKarenia mikimotoihave been isolated, yet the distribution of the algicidal bacteria has been rarely studied. Here, we postulated and demonstrated that terrestrial environment harbors diverse algicidal bacteria, which can survive in seawater along water flowing into marine and suppressKarenia mikimotoi. In summary, 9 and 5 bacteria with algicidal activity onKarenia mikimotoiwere isolated from seawater and estuarine soil, respectively. Similar with the marine bacteria (Alteromonassp.,Halomonassp.,Marinobactersp.,Paracoccussp.,Rhodobacteraceae,Idiomarinasp.), the soil strains (Pseudoalteromonassp. andFlavobateriumsp.) showed high mortality inKarenia mikimotoiwith the inhibitory rate of 87% and 93.5%, respectively, after two days co-cultivation. Algicidal activity of the two strains was detected in the cell-free filtrate not in bacterial cells. The results suggest that algicidal bacteria associated withKarenia mikimotoiwidely exist in terrestrial and marine environments, and have application potential on controllingKarenia mikimotoi.