Characterization Analysis Of Antagonists By BY Strain And Preliminary Study On The Prevention And Control Of "Black Pimple"

In recent years,as people pay more and more attention to environmental and food safety problems,people gradually recognize the harm of chemical pesticide use in the pest control of agricultural products.The result of it is that people attaching more importance to biological control.The search of broad-spectrum and efficient biocontrol strains is quiet crucial to the biological control process.By using the plate sputum method,the bacteriostasis experiment of the organic solvent extract of the fermentation broth of BY and B1,and using Escherichia coli,Staphylococcus aureus,cherry tree"black lump"disease possible pathogens and plant pathogenic fungi as indicator strains,antagonistic bacteria BY and B1 preserved in laboratory were screened.The experiment result shows that the crude extracts of BY and B1 have antibacterial activity against bacteria.However,only the absolute ethanol extract of fermentation broth of antagonistic BY has a good inhibitory effect on plant pathogenic fungiwhile that of B1 has no inhibitory effect.Therefore,an antagonistic BY with a broad antibacterial spectrum is obtained then identified as Paenibacillus sp.by using morphological,physiological and biochemical experiment and 16S rRNA gene sequencing analysis.The crude ethanol extract of fermentation broth of antagonistic BY was deproteinized by sevag method,and then analyzed by thin layer chromatography?TLC?and full wavelength scanning.Results shows that the crude extract of BY is polysaccharide.Then purify the crude extract by DEAE-23 chromatography and Sephadex G-100 chromatography to obtain bacteriostatic polysaccharide PoI1a.The molecular weight of polysaccharide PoI1a was determined by high performance gel permeation chromatography?HPGPC?to be 9.78KDa.Then analyzed by gas chromatography?GC?,the polysaccharide PoI1a is composed of rhamnose?5.81%?,fucose?1.77%?,arabinose?5.29%?,mannose?13.90%?,glucose?44.80%?,Composition of galactose?28.43%?.The substance PoII extracted from the ethanol of fermentation broth of antibacterial BY has a scavenging function on hydroxyl radicals,and the component PoII1 and PoII2 are obtained by DEAE-23 chromatography from substance PoII.Both component PoII1 and PoII2have hydroxyl radical?·OH-?scavenging and DPPH scavenging function.In orthogonal test,the optimum carbon and nitrogen source for the medium of BY is determined to be maltose?20g/L?,NaNO₃?0.5 g/L?,and the pH was 6,and the liquid filling coefficient was 0.4.Anhydrous ethanol extract of antagonistic bacteria BY fermentation broth has the strongest bacteriostatic effect in the optimum medium.When the condition is 30-70°C and pH of 2-7,the crude extractof fermentation broth of the antagonistic BY has no effect on the antibacterial activity.In order to study the"black lump"disease of cherry trees in Bailuyuan of Shaanxi Province,the TianYuan modern agricultural cherry garden of Bailuyuan was selected as the experimental field.In the first batch of experiment,5 groups of"black lump"diseased cherry tree was used as the experimental group named"Da,Db,Dc,Dd,De",and the diseased tissue was respectively treated by removing the rind or not.Then different treatment liquids?No.1,No.2,No.3,No.4 control liquid?were applied to the diseased tissues.Check the disease control results at different time.The result shows that the prevention that scraping diseased tissue works and the effect of No.1 and No.4 control solution is better.In the second batch of experimental groups,four different diseased tissues D1,D2,D3 and D4 are selected as the experimental group,and another four diseased tissues are taken as CK1,CK2,CK3 and CK4 to be blank control.The experimental group was treated scraping off the diseased tissue or did not treat it then apply No.1 and No.4 control solution respectively.In the control group,the diseased tissue was scraped off,and the untreated and only sterile water was sprayed.The disease of the experimental group was inhibited,and there is no gummosis at all,but the disease in the control group became severe.BYstrain has control effect on the prevention and control of"black lump"disease in cherry trees,but the prevention period is long.The prevention and treatment of less serious"black lump"disease is better.Therefore,the cure and treatment of"black lump"disease by BY strain is mainly advance prevention.