Antimicrobial Spectrum of A Biocontrol Bacterium Strain LN04 and the Characterics of Its Antibacerial Protein

The bacterium strain LN04, identified as Bacillus sp , was screened from drain outlet of a eel culture farm. The broth of LN04 showed high inhibitory effects against a number of aquatic pathogens including Aeromonas hydrophila,Edwardsiella tarda, Nocardia asteroides,and Vibrio anguillarum. A kind of antibacterial protein was gained by sulfate precipitation and dialysis from supernatant of LN04. In the following test, this active substance was proved as thermostable and aciduric but sensitive to some proteases. The strong antagonistic ability of LN04’s antibacterial protein, together with its high stability to environmental factors, reveals that LN04 can be used as a biocontrol bacterium for the bacterial disease control and prevention in fresh water aquaculture.