Purification of Two Antimicrobial Substances Produced by Bacillus subtilis Strain B11 and Their Properties

Two antimicrobial substances produced by Bacillus subtilis strain B11 were purified by boiling, DEAE 52 anion exchange chromatography and aluminum oxide adsorption chromatography. These purified substances showed only one spot on silica gel thin layer chromatography (TLC). Antimicrobial assays showed that antimicrobial substances A and B inhibited the growth of plant pathogens such as Fusarium oxysporum Schl f.sp. niveum, Rhizoctonia solani, Ralstonia solanacearum and Xanthomonas oryzae pv. oryzae. In addition, antimicrobial substance B could also inhibit the growth of Magnaporthe grisea. These two antimicrobial substances were resistant to proteolytic enzymes and temperature as high as 121°C.