The Study On Biocontrol Of Post Harvest Diseases Of Muscat Grapes By Burkholderia Contaminans B-1

Muscat grapes is well received by consumers for its high sugar content and rich flavor.However,it was easy rot during postharvest for thin peel,big juice volume and other characteristics,Although SO2 fumigation combined with low temperature storage technology can effectively suppress reduce the occurrence of disease,But the technology should led to resistance of pathogens increased,environmental pollution,health decline problem and other bad influence,issues would be generated,So we need to find a new technology to gradually replace it.Biocontrol is just known as a potential technology used in postharvest storage currently.In this study we evaluated the biocontrol activity in vitro and in vivo of Burkholderia contaminans B-1 against major grape postharvest pathogen and study the biocontrol mechanisms.The main results were as follows:(1)In vitro experiment,When confrontation with Botrytis cinerea,inhibition zone of antagontisic bacteria with 24h culture is largest and most clear,the diameter is 3.15cm.It shows that the production of the metabolites of antifungal activity maybe the one of the possible antibacterial mechanism.Through the contact and non-contact confrontation training experiment further found that Inhibitory effect need have some contacts.From the different treatment of B.contaminans B-I against Botrytis cinerea,the bacterial suspension and fermentation broth have the strongest inhibition effect,other treatment have no significant inhibition effect.It speculated further that antimicrobial active substances may be produced in the intracellular or around the cell wall and attached to the outer wall.In addition,B.contaminans B-1 has impact the spore germination rate and mycelial morphology of Botrytis cinerea.Confront culture against other postharvest pathogens of fruits and vegetables,the antagonistic bacteria showed good antifungal effect.(2)In vivo experiment,B.contaminans B-1 were spray on grape surface can significantly reduce the amount of pathogens before harvest.The antagonistic bacteria has the strongest inhibitory activity on after 24 hours inoculation.Under three different temperature of 26?,16?and 0?,the fermented liquid which dilution five times and bacteria suspension has better inhibition effect than other treatments.The antagonistic bacteria and pathogens inoculation on fruit wounds founds antagonistic bacteria delayed gray mold spore germination and mycelium elongation,In addition,the antagonistic bacteria treatment may delay the rate of decline of content of essential nutrients during fruit storage,to maintain the basic quality of the fruit.(3)The benzene propane metabolic pathways and active oxygen metabolic pathways of the grape were effected by B.contaminans B-1.The activities of the phenylalanine ammonia-lyase(PAL),peroxidase(POD),superoxide dismutase(SOD),hydrogen peroxide(H2O2)and polyphenloxidase(PPO)were enhanced significantly.The peak time was delayed of catalase(CAT)of the grape inoculated by antagonistic bacteria.In addition,the activities of chitinase(CHI)and?-1,3-glucanase(GLU)were increased.(4)The response surface optimization test was used to screen optimization formulation of B.contaminans B-1.Formula include 2.11%malt extract,1.9%yeast extract,0.05%potassium dihydrogen phosphate and 0.05%manganese sulfate.