Extraction and application of bacteriostatic active substance of Bacillus marinus B-9987

The invention relates to the technical field of biological pesticides and particularly relates to extraction and application of a bacteriostatic active substance of Bacillus marinus B-9987. The invention aims to provide extraction of a bacteriostatic substance from a Bacillus marinus B-9987 strain and determination of pathogenic bacteria with optimal prevention and treatment effects on plant fungus diseases. The extraction and the application involve (1) the extraction of the bacteriostatic substance from the Bacillus marinus B-9987 strain; (2) purification of the bacteriostatic substance; and (3) a method of application of the bacteriostatic substance. According to the extraction and the application, the used steps are simple, and the used adjuvant is cheap, so that the selection and use for researches of scientific research personnel are facilitated; and the ratio of bacteriostasis to the plant fungus diseases is assayed, the pathogenic bacteria with the optimal prevention and treatment effects are determined by a simple method, and thus convenience is provided for application in the prevention and treatment of the diseases in practice.