Abstract: This work is to isolate and screen the antagonistic bacteria from sea environment which can inhibit the growth of the seaperch’s pathogenic bacterium Vibrio anguillarum W-1, and investigate the optimal conditions of its antimicrobial activity as well as the drug sensitivity. The methods of plate crossing streaking and point-inoculating were used to screen the antagonistic bacteria. The morphology, physiological and biochemical reactions and 16S rDNA phylogenetic analysis were applied for the identification of antagonistic bacteria. The one-variable method was utilized to optimize the antimicrobial conditions of the antagonistic bacteria. Total 126 strains of bacteria were isolated from the coast of Qingdao, Xiamen and Shidao, and 19 antagonistic bacteria were screened. The bacterial strain WTD with the optimal antagonistic activity was identified as Bacillus amyloliquefaciens. Under the optimal conditions of 35℃, salinity 1% NaCl, and pH 7, the antagonistic effect was the best. The drug sensitivity test revealed that the bacterium was sensitive to 29 antibiotics such as midecamycin, but resistant to polymyxin. As a conclusion, the antagonistic strain B. amyloliquefaciens WTD can efficiently inhibit the growth of the seaperch’s pathogenic bacterium V. anguillarum, and has the potential application value in the aquaculture.

Key words: Bacillus amyloliquefaciens, Vibrio anguillarum, antimicrobial activity, antagonistic bacteria