Study On The Separation Of Hami Melon Postharvest Pathogen And Its Biological Control Technology

Soft rot, black spot, white mildew, green mildew of Melon was the main infectious disease duringstorage and caused decay losses seriously. For a long time, the prevention and control of fruit postharvestdiseases stayed in the traditional chemical fungicide. using chemical fungicide could lead to drug residues,long-term using could cause environmental pollution and eventually posed a hazard to the health of human.Along with the increasingly attention to food safety, there was an urgent need for a new fresh keepingmethod to replace chemical fungicide. Microbial control was a method which selected microorganismswithout harm to the fruit as well as the human body, and achieved the purpose of suppressing the growthof pathogenic bacteria by microbial antagonism.The separation of the main pathogenic bacteria of Hami melon storage during P4, P5and P7, screenedantagonistic strains J2, J5and separation, the antagonistic, chitosan and storage temperature were studiedby orthogonal test. Eventually, this paper preferred a biological preservative and verify its preservationeffect on the cantaloupe. The main results were as follows:1.Isolation and purification of the pathogen of Hami melon disease bacteria through, finally get themain pathogenic strain5melon bacteria; by morphological and physiological biochemical tests andmicroscopy identification of pathogen. P4was identified as Penicillium expansum, belonging to theAspergillus, Penicillium; P5belongs to the genus Fusarium; P6belongs to the family of Aspergillus niger;P7for Alternaria; P8belongs to the genus mucor.2.By dilution plate method, experiment115strains were isolated, including20strains of yeast,95strains of bacteria. Through in vitro selectionand in vivo screening, finally won the2yeast strainsantagonistic performance excellent, named J2and J5. By morphological, physiological and biochemicaland molecular identification of J2synthesis for Cryptococcus laurentii; J5for Cryptococcus laurentiivariant3.By the single factor and orthogonal experiment to determine the optimal conditions for activation ofJ2culture time48h, medium concentration10Brix, liquid volume100mL; the antibacterial vaccinationtime interval and different treatment liquid antibacterial experiment of antagonistic, speculated that thespatial competition may be one of the main mechanism of antagonistic bacterium J2.4.Under the condition of4℃, through the determination of growth curve of the antagonistic bacteriaJ2turbidimetric method, to obtain the optimal carbon source, nitrogen source, low temperature stress weresucrose, peptone, add0.1mol/L Ca²⁺ and2%trehalose were significantly enhanced antibacterial ability ofAntagonistic Yeast J25.The best preservative formula of hami melon was finally obtained through the single factorexperiment and orthogonal experiment: Jasmonic acid methyl Chitosan concentration of0.5%, antagonisticbacteria of J2, bacterial suspension concentration of108cfu/mL, storage temperature of5℃.6.Preservative effect validation: It could evidently inhibit the respiratory intensity of fruits duringstorage and delay the climacteric peak after using this antistaling agent on melon, Inhibit activity decreaseof the enzyme SOD and POD and hold back the rises of PPO activity. Keep the melon hardness, sugarcontent and Vc content, delaying after-ripening of melon. This biological preservative had certain effect on reducing the rate of decay, delaying the senescence of melon, keeping melon quality.