Effect Of Trichoderma Asperellum Fermentation Broth On Apple Preservation

Apple has abundant water content and a wide range of nutrients,which is popular among people of all ages.However,when apples are picked,transported and stored from the production site,a variety of pathogens will invade and cause serious diseases,which will lead to Apple decay and loss of commercial value.Among them,Alternaria alternata and Colletotrichum gloeosporioides are common diseases in postharvest apple.For the prevention and control of these apple postharvest diseases,although the traditional chemical preservatives have significant antibacterial and fresh-keeping effects,the chemical residues in fruits and vegetables may endanger human health,and the use of chemical preservatives will also cause certain pollution to the environment.However,Trichoderma asperellum has antagonistic effect on a variety of pathogens causing fruit rot disease,and it can survive in a large number in the natural environment without adverse effects on human body.It is a kind of Antagonistic Fungi with development prospects in the application of fruit and vegetable preservation.In this paper,the cell walls of Alternaria sp.and Colletotrichum sp.were used as carbon sources to induce and culture Trichoderma asperellum.The expression of hydrolase and antibiotic genes in Trichoderma asperellum was determined.The activity of hydrolase and the type and content of antibiotic in the fermentation broth of Trichoderma asperellum were determined to find out the highest culture time of enzyme activity after induction.At the same time,the apple was soaked in the fermentation broth of Trichoderma asperellum with the highest enzyme activity.(1)The effects of cell wall culture of Colletotrichum gloeosporioides and Alternaria alternata on the gene expression of hydrolases and antibiotics were studied.The results showed that the cell walls of Alternaria alternata and Colletotrichum gloeosporioides were used as carbon sources to induce the expression of chitinase gene ech42,β-1,3-glucanase gene bgn13,aspartate protease gene asp1,aspartate protease gene asp2 and polyketide synthase gene pkst1,but not n-acetylglucosaminidase gene nag1.(2)The effects of cell wall culture of Alternaria alternata and Colletotrichum gloeosporioides on the hydrolase production of Trichoderma asperellum were studied,The content of 6-amyl-α-Pyranone was determined.The results showed that chitinase,n-acetylglucosaminidase,β-1,3-glucanase,β-glucosidase and cellulase were induced by cell wall culture of Colletotrichum gloeosporioides and Alternaria alternata.Antibacterial substance 6-amyl-α-Pyranone in fermentation broth after induction,the content of pyranone was 1.72 mg/mL.(3)The control effect of Trichoderma asperellum fermentation broth induced by cell wall of pathogen on Apple Anthracnose and mold core was studied.The results showed that the control effect was 45.9%for mycoheart disease and 53.3%for anthrax.It also showed that echinospore fermentation liquid could effectively control the occurrence of apple postharvest diseases.(4)Fuji Apple was used as material to study the effects of Trichoderma asperellum fermentation broth induced by pathogen cell wall on apple texture characteristics,nutritional components,respiration rate and MDA value during storage.The results showed that the fermented liquid could delay the decline of elasticity,chewiness,hardness,TSS,TA and Vc,and increase the weight loss rate,respiration rate and MDA value of apple.