Isolation And Identification Of Antagonistic Bacteria BB-B Against Wheat Powdery Mildew And Study On Its Control Effect

Wheat powdery mildew is one of the diseases that seriously affect the safety of wheat production in China. At present, the prevention and control measures for the disease are mainly chemical control and disease resistant breeding. Long-term or excessive use of chemical pesticides, often resulting in increased resistance to powdery mildew, pesticide residues and environmental pollution, and breeding cycle is long and easy to lose resistance. Therefore, separation of biological control agents without pollution to human and natural low toxicity has been the research focus of disease prevention and control.This study through the wheat in the soil of the root of isolated for screening for antagonistic bacteria pathogen Blumeria graminis(Blumeria graminis f.sp. Tritici) of Wheat Powdery Mildew Induced, to obtain a strain has stronger antibacterial effect of biocontrol agents(referred to as BB-B). The strain, screening, identification, fermentation culture conditions optimization, antibacterial active ingredient analysis and application of preliminary research and analysis. The main results are as follows:The antibacterial effect of antagonistic strain BB-B was stable, and the inhibition rate reached 59.82%. Through the morphological characteristics, physiological and biochemical characteristics and 16 SrDNA sequence analysis and identification of antagonistic strain BB-B, it was identified as Bacillus subtilis(subtilis Bacillus).In order to verify the antagonistic effect of the fermentation broth of strain BB-B on wheat powdery mildew, the condition of strain BB-B culture was optimized. By single factor experiments, it was found that the best C source and N source were: C source glucose, N source soybean meal. The Pb tests, from eight main factors found to test the effect of significant factors for: C source and N source and speed. The three factor response surface experiments, through variance analysis, calculated the optimal test conditions: C source of 7 g / L, N source 5 g / L, and the speed is 220 r/min, under these conditions, the inhibitory effect is best, can reach 72%. The average value of the inhibition rate was 69.71%, and the difference between the theoretical value and the theoretical value was 3%.The fermentation broth of strain BB-B in crude extracts composition antibacterial activity including protease, chitinase and siderophore. Artificial potted inoculation control test, bacteriostatic effect and is proportional to the concentration, test of antagonistic bacteria fermentation broth concentration close to 100% when the maximum effect was 37%. The results showed that the antagonistic bacteria fermentation broth concentration higher inhibitory effect is better.The separation to wheat powdery mildew high effective biocontrol strains, and to optimize the biocontrol agent, the optimum fermentation process, so as to lay a foundation for further application.