Screening Of Antagonistic Bacteria To Coniothyrium Diplodiella And The Analysis Of Antifungal Substances

Chemical pesticides are the main method of the fungal control. Chemical controlof disease is costly both to the farmer and to the environment. There are massivebeneficial microorganisms in the soil. Strains that can inhibit the growth of a lot ofplant pathogenic fungi can be obtained. This research aims at isolating and screeningof antagonistic bacteria with great activity to plant pathogens. Taking beef extractpeptone medium as the separating medium, some strains of bacteria were separatedfrom the soil. By initial screening,59strains of bacteria which inhibit the growth ofConiothyrium diplodiella were screened out.1strains of bacteria that inhabit thegrowth of many plant pathogenic fungi were screened out. L26with clear antifungalactivity was isolated which inhibits many plant pathogenic fungi growth such asConiothyrium diplodiella, Fusarium Oxysporum, Bipolaris maydis, and Colletotrichumlindemuthianum.The antimicrobial substance produced by Bacillus subtilis L26was purified byanion-exchange chromatography and ammonium sulfate precipitation and HiPrepSuperdex75HR, and the antimicrobial substance was analyzed by HPLC。The study shows that the antimicrobial substance was heat-stable, inactivated byproteolytic enzymes (protease K, pepsin, papain), not sensitive to pH and stronglyinhibit many plant pathogenic fungi, however, the substance shows little enzymeactivity. Maybe the substance loses its enzyme activity when passes all the procedure.A number of Bacillus strains have proven safe over many years as anonpathogenic species. The substance isolated from the Strains of Bacillus hasseveral advantages over other antimicrobial substance in that they are stable, easy tostore, and it has the potentiality to become a primer of the bio-pesticide.