Study On The Application Of Antagonistic Yeasts Against Broccoli Black Spot

Black spot is the most common disease with the highest incidence in broccol post-harvest storage and transportation.In this study,the screened antagonistic yeast was used to biologically control black spot disease of broccoli,and the mechanism of prevention and control was explored through in vitro and in vivo experiments.The yeast was made into fresh-keeping paper products and its preservation effect on broccoli was explored.The main results were as follows:(1)The GS506-1 yeast obtained through screening is round and adopts the splitting method of budding.It does not produce ascospores and pseudohyphae,can ferment and assimilate glucose,trehalose,soluble starch,but also assimilate mannitol,sucrose,urea,ammonium sulfate and ammonium nitrate.Molecular identification results showed that the genus is a genus of P.membranaefaciens.(2)The results of in vitro experiments showed that in the 105?108 concentration range,the inhibitory effect of the black spot pathogen was more obvious with the increase of the concentration of the yeast suspension.108 CFU/mL yeast suspension had the highest inhibitory rate to pathogenic bacteria growth and spore germination after Id,which were 87.9%and 90.97%.GS506-1 yeast can secrete antibacterial substances to inhibit the growth of mycelia.Microscopic observations revealed that GS506-1 yeast caused the mycelium of pathogenic bacteria to bend,the contents overflowed,and the pathogenic spores split and disintegrated.(3)The application results of broccoli showed that GS506-1 yeast could rapidly proliferate at the wound site of broccoli at a concentration of 105 CFU/mL.The activity of defense enzymes PPO,POD,PAL and CAT in broccoli was increased and the increase of MDA content caused by pathogenic bacteria was reduce.Different concentrations of yeast suspension can maintain the content of chlorophyll,vitamin C and soluble sugar during the storage of broccoli.However,it was found that the high-concentration(108 CFU/mL)yeast suspension had a better preservation effect than the low-concentration(105 CFU/mL),and the lesion diameter and incidence of broccoli treated with 108 CFU/mL yeast suspension was only 4.70 mm and 21.27%on the 7th day.(4)The preliminary formulation of the bio-preservation paper was determined:1%gelatin,108 CFU/mL yeast suspension,1%sodium alginate,1%seaweed Mix the sugar in a ratio of 1:2:1:1,soak semi-permeable sulfuric acid paperthe paper and drain.The results of yeast viability,scanning electron microscopy,and fresh-keeping effects of the cling-paper products during storage showed that on the 30th day,the yeast on the fresh-keeping paper did not produce significant shrinkage,and the survival rate was less than 10%at the 60th day,at the same time,it has lost its use value.Fresh-keeping paper packaging can cut off the direct contact between broccoli and the outside world.Combining broccoli commercial storage technology,in addition to maintaining the original quality,it can slow down the occurrence of black spot.