The Characterization of Antagonistic Bacterium A014 and Its Antibacterial Proteins

A strain of Bacillus spp. has been screened from thousands of bacteria isolated from rice paddy field. The strain can secrete large amount of antibacterial proteins and has a strong in hibiting activity against the pathogen of rice leaf blight disease. Eight species in 4 genera of plant bacterial pathogens were tested for the antibacterial spectrum with the antibacterial proteins and results indicate strong inhibiting the growth of 4 species bacteria of xanthomonads and pseudomonads. Large amount of antibacterial proteins have been extracted by (NH4)2SO4 precipitation from overnight culture of king’s B medium. Further experiments are underway to purify the antibacterial protein with chromatography and to clone the gene encoding the protein.