The Inhibition Mechanism Of Bacillus Amyloliquefaciens

Large-scale cultivation of farmland, making the pests more serious, leading to the prevailing chemical control methods excessive abuse of drugs leads to pathogen resistance. At this time the awareness of environmental and food safety issues are also increasingly concerned.Therefor bio-control method to pathogens came into being. Currently Bacillus amyloliquefaciens main used as fungicide, bio-fertilizer, wettable powders and other products.Strains QHL-52 and QHL-30 isolated from the Qinghai plateau environment, using morphological, microscopic characteristics, physiological and biochemical characteristics and molecular conserved region sequence analysis, were identified as Bacillus amyloliquefaciens; measured by its inhibitory spectrum plate confrontation method, two antagonistic bacteria had inhibition to a variety of plant pathogens; control effect in vitro assay results indicate that the crude fermentation broth of the two antagonistic bacteria can effectively prevent Botrytis cinerea; detected strains capable of producing siderophore, glucanase, protease and amylase. By acid precipitation and ammonium sulfate precipitation of antagonistic bacteria fermentation, detected a number of protein bands by SDS-PAGE, due to the instability activity did not continue the test, and lipopeptide antibiotic. Related to genetic testing showed that two antagonistic bacteria contain iturin and Fengyuan synthetase gene absence of surfactin related genes.Antibacterial mechanism inquiry test showed that two antagonistic bacteria are capable of inducing resistance to the plant itself, which POD, SOD, PPO, PAL, APX, CAT activity were significantly higher content and MDA content was significantly lower than the control group, description antagonistic bacteria can induce plants produce their own favorable factors, eradicate their own adverse external factors. And antagonistic bacteria synergy together to combat the adverse environmental or external injuries. Meanwhile broth can destroy pathogens cell structure, so that Botrytis cinerea mycelium produces nodules, swelling and a large amount of top branches hyphae cell constriction crack cytoplasm leakage leading to cell death, so that adhesions or direct rupture between the spore wall, spore Germination play a significant inhibitory effect, and is accompanied by a large number of crystals appear.After separation and purification of two antagonistic bacteriostatic substances, yielding different components of antimicrobial substances, mainly antibacterial substance of strains QHL-52 were volatile substances, through extraction and separation and purification of the supernatant metabolites, the resulting sample also has a strong inhibitory effect; the main inhibitory substance QHL-30 for protein substances, may also be part of the role lipopeptide antibiotics.