Isolation And Identification Of Antagonistic Bacterium RB5Against Rhizoctonia Cereasis And Studies On Antifungal Activity

Infection of Rhizoctonia cerealis causing sharp eyespot of wheat greatly affected thewheat yield. With the extensive use of chemical pesticides, soil salinization, anddamage to the environment has become increasingly serious, the development of bothdisease and pest control, pollution, damage to the environment without the drug isimminent, the soil contains a lot of beneficial microorganisms, their metabolicproducts can pest control and to promote plant growth. The rhizosphere soil fromwheat, screening for Rhizoctonia cerealis higher antagonistic strains and speciesidentification was carried out and antibacterial activity in wheat sheath blightbiocontrol of effective prevention and sterilization foundation for the developmentagents.From the rhizosphere soils of wheat of158strains of bacteria purified by repeatedscreening plate confrontation experiment found that7strains of bacteria inhibitoryeffect is good. In which the strongest antibacterial RB5inhibition rate reached78.6%.Antimicrobial activity of fermentation58.2%. According to morphological,physiological and biochemical characteristics and16S rDNA sequence determinationof the antagonistic bacteria identified as Pseudomonas fluorescens RB5(Pseudomonas sp.).Through the microscope by the antagonistic bacteria fermentation treated myceliumof Rhizoctonia cerealis and found that the apparent bending hyphae and rupture.Determination of the fermented liquid treated mycelium production of three cell walldegrading enzyme activity, its activity is significantly lower than in the control group.When RB5100%fermentation when the concentration of poly-galacturonic acidenzyme (PG), pectin methyl galacturonic acid enzyme (PMG) and pectin methyltrans-elimination enzyme (PMTE) the activity of three enzymes maximum inhibition,respectively,87.83%,97.98%and94.68%.RB5antagonistic bacteria to enhance the antibacterial activity of fermentationproducts, using the response surface optimization of fermentation conditions C and Nsources were the source of the single factor optimization of glycerol as C source, yeastextract as N source has a high antibacterial activity.Response surface optimization of fermentation tests showed that soybean meal as a Nsource, the fermentation of cassava as a C source has a good antibacterial effect, PBexperiment to find out the impact of the significant factors experiment C source, N source, and speed. By response surface experiments, the best78%inhibition, andfinding the optimal experimental conditions for the C source of87%, N source of52%,speed218r/min.RB5clearly antagonistic bacteria for the fermentation broth of active ingredients,were siderophore, protease, chitinase, the detection of hydrocyanic acid and othermetabolites was found in the fermentation broth containing these metabolites. At thesame time siderophore was detected, and the design of primers, specific primers havebeen. Found in the molecular detection of the generation of PRN RB5contain genesPrnd.Finally, Indoor control effect of up to36%. To further verify the strain RB5actualeffect of the fermentation broth processing, the control effect of indoor pot experiment,the indoor control efficiency of up to36%. RB5demonstrated good resistance toRhizoctonia cerealis capacity.