Abstract: In order to obtain antagonistic bacteria against Botrytis cinerea, about 200 strains of bacteria isolated from soil samples were screened with the agar plate diffusion method. After primary and secondary screening, the strain X-75 showed the most significant antagonistic activity. After the morphological
observation and a series of physiological and biochemistry experiments, the bacterial strain X-75 was primarily identified as Bacillus sp. The similarity of the 16S rDNA sequences between X-75 strain and AB245422 Bacillus velezensis was 99.93%, so it was finally identified as the nearest genetic relationship with
Bacillus velezensis. And the X-75 strain showed obvious antagonistic activity against Botrytis cinerea Pers on tomato leaves.

Key words: tomato, Botrytis cinerea Pers, Bacillus, antagonistic activity