Isolation And Identifieation Of Antagonist Bacillus Amyloliquefaciens To Magnaporthe Grisea And Its Antimicrobial Mechanism

Rice blast is one of most widely distributed of the most serious hazards all over the world. At present, the main control method of rice blast is chemical control, but a large number of long-term using causes resistance and resistance to pathogens, environmental damage and pollution, and threatens to human and animal health. Therefore, under the condition does not damage the environment, to maximize the rice production, more and more people choose to biological pesticides to prevent rice blast.In this study, samples from coastal waters collected in Dalian Development Zone, and 83 strains are isolated. Using the method of tablet confrontation and Oxford cup, antibacterial experiments of rice blast show that 4 marine bacteria are antibacterial, in which inhibitory effect of bacteria is most obvious,and named for the strain No.BCHN-15.And the rice blast inhibition zone diameter is 41.4mm. By morphological observation, physiological and biochemical identification, 16 S rDNA sequencing, BCHN-15 strain is identified as Bacillus amyloliquefaciens.BCHN-15 strain is a broad-spectrum antimicrobial activity of microorganism,which microbial metabolites produced by Magnaporthe grisea,Fusarium graminearum,Fusarium solani, Curvularia lunata Boedijn, Xanthomonas oryzae and Candidia albicans have a certain extent antibacterial activity. Metabolites of BCHN-15 strain can inhibit the growth of mycelium, and mycelium dry weight decreased 74.36% compared with the control group. Optical microscopy and scanning electron microscopy results show that after BCHN-15 strain broth role,morphological changes mycelium rice blast and appeares swelling, deformity, vesicles and breakage. BCHN 15-mechanism results show inhibitory effect of rice blast, antimicrobial active ingredients of BCHN-15 strain can damage the permeability of cell membranes of Magnaporthe grisea, so that the contents of Magnaporthe grisea such as intracellular inorganic ions, DNA and RNA and other macromolecules, soluble sugar and soluble protein, resulting in cell death of Magnaporthe grisea. Strain broth of BCHN-15 produced by heat-stable, but sensitive to pH. The antimicrobial active ingredients can be obtained by acid precipitation from fermentation broth, which has significant antibacterial activity,and the supernatant fraction also has some antibacterial activity, but the isolation and identification of antibacterial ingredients need study in further.