Identification Of A Phlorizin Allelochemicals Degradation Bacteria And Colonization In The Rhizosphere Of Apple

Apple is the largest fruit varieties in china,has a variety of nutrients,which belongs to the Rosaceae Malus,The planting area of apples about 200 km2,the planting area and production were accounted for 40%of the world.However,apple continuous cropping obstacles is a big problem facing the world apple industry,the low survival rate of continuous cropping of apple seedlings and root dysplasia influence the yield and quality of apple.The study showed that autotoxicity is one of the main reasons for continuous cropping obstacles,which can damage the balance of microecological environment seriously.Phlorizin is characteristic of the phenolic compounds of Malus,when the concentration of phloridzin was reached 0.001 mmol/L can promote the growth of seedlings,but the concentration reached 1mmol/L can inhibit the seedling growth,reduce the accumulation of dry matter,and with the concentration of phloridzin increase,the inhibition strengthened.In addition,phloridzin phlorizin prime,benzene three phenol and cinnamic acid were belong to degradation product of phloridzin,which can can inhibit the growth of fruit trees.Microbes can influence the number and variety of toxic substances,It’s plays an important role for alleviating autotoxicity.Some microorganisms can utilize phlorizin and other phenolic acids autotoxins as only carbon source,which could eliminate or alleviate autotoxicity;some beneficial microorganisms could Control the amount of pathogenic bacteria or interference Infection of pathogen bacteria in soil,which could alleviate autotoxicity indirectly;Some beneficial microorganisms develop the plants Through Produce secondary metabolism,such as plant hormones and antibiotics.The soils were sampled by three-point-sampling method from 4-5 years old apple tree rhizosphere in cherry garden of Shandong province Tai’an City.The Phlorizin degradation bacteria were separated using selective medium and constantly domestication methods.with mensuration biologos of each strains,the strains with higher liveness was selected to study the colonization regularity.Two degrading bacterias which have strong Phlorizin degradation ability were selected and then to study these biological safety.The strain G-19 was identified by thalli shape and bacterial colony,physiology and biochemistry indicator analysis,16S rDNA analytic.To study the optimum media composition and fermentation conditions and to study the strain relieve the harm of Phlorizin allelochemicals by pot experiment.The main results were as follows:1.22 isolates of Phlorizin degradation bacteria were isolated from apple tree rhizosphere soil.2.The Phlorizin degradation rate of 22 isolates Phlorizin degradation bacteria were situated in 5.00%-75.9%,and the strainsG-19、G-9、and G-5were the best of all.3.Through antibiotic markers and soil inoculation test,3 degrading bacterias which have strong Phlorizin degradation ability in apple tree rhizosphere colonization ability were researched,and the strain G-19,G-5 can colonize stable in apple tree rhizosphere.4.Safety detection:The result of examined for biological safety evaluation,the strain G-19 was consistent with NY 1109-2006 "microbial fertilizer biological safety general technical standards" requirements,which can be used as a strain for microbial fertilizer production;hemolytic Hemolysis test for G-9 showed positive,which does not consistent with the safety requirements for strains as microbial fertilizer production.5.The results of thalli shape and bacterial colony,physiology and biochemistry indicator analysis,16S rDNA analytic show that the G-19 belonged to a kind of Enterobacter radicincincitans6.Selecting the common carbon and nitrogen sources and inorganic salts.To design orthogonal experiment and Optimization of culture medium.The Medium components and Fermentation conditions of G-19 as follows:Medium components:Glucose 10.00g,indian meal 40.Og,soybean powde 20.0g,(NH4)2SO4 0.5g,KH2PO4 0.5g,CaCO3 0.6g,water 1L.Fermentation conditions:liquid volume 50mL/250mL,Rotational Speed:200r/minin,temperature:32 ℃,pH 7.0,shake flask culture 24h.7.Pot experiment results show that the strain G-19 has good degradation effect of the Phlorizin,and the G-19 can effectively alleviate and eliminate the harm of Phlorizin bring on apple seedlings.