Isolation, Identification And Optimization Of Fermentation Conditions Of Antagonistic Bacillus On Plant Pathogen From Soybean Paste

To filter out antagonistic Bacillus on plant pathogen,reduce the use of chemical pesticides and provide data and theoretical basis for the biological control of plant technology.228 kinds of Bacillus were separated from 69 kinds of miso which collected from Jilin, Heilongjiang, Liaoning, Shandong province.The result showed that 26 kinds of Bacillus showed broad-spectrum antimicrobial activity on Rhodiola root rot,Rice bakanae disease, Rice sheath blight,Cucumis melo and peppers anthracnose, Cabbage sclerotinia.By screening,11 kinds of Bacillus have efficient antagonistic activity on these six kinds of pathogenic and the minimum inhibitory rate was all over 60% and its broth inhibitory rate was all over 35%. In the Bacillus, the highest inhibition rates of SP-5 strain on Rice bakanae disease, SP-13 strain on Rice sheath blight, SP-6 strain on Cucumis melo anthracnose, SP-13 strain on Cabbage sclerotinia, SP-44 strain on peppers anthracnose, SP-163 on Rhodiola root rot were 79%、88%,82%,88%,89% and 77%.The highest inhibitory rate of Bacillus broth on the 6 plant pathogens were the 65.38% of SP-6,61.91% of SP-130, 64.70% of SP-6,6526% of SP-5,66.90% and 42.59% of SP-16.Under the microscope, the mycelium body deformity phenomenon by plate confrontation method will be deformed.Just as contortion,slimmer,fractured, protoplasm condense,dissoved,swilling and color burn.According to the oxidation fermentation test, IMViC experiment, substrate and enzyme assays with experimental binding cell morphology observation, initially identified 11 strains of the genus as Bacillus or Paenibacillus.According to 16SrDNA sequence homo logy and phylogenetic tree analysis, combined with the strain morphology, cultural characteristics and physiological and biochemical characteristics, SP-6, SP-13, SP-14 strain were identified as Bacillus amyloliquefaciens, Bacillus methylnutrition and Bacillus subtilis.The optimization of fermentation conditions results showed that the optimum carbon source,most nitrogen source salt of SP-6, SP-13, SP-14 strain was lactose, soybean peptone.The optimum fermentation temperature,the optimum inoculation amount and the most fitness liquid volume was 32℃,5%, and 100 mL (per 250 mL), the optimum initial pH of SP-6 and SP-13 strain value was 7,and SP-14 strain was 6.Conclusion:There were a large number of Bacillus having high antagonistic efficiency on plant pathogen in soybean paste, which was a great significance to promote the progress of biological control of plant technology.