Bacteriostatic Mechanism And Preservation Application Of Bacillus Atrophaeus CP 297 And Bacillus Amyloliquefaciens CP 2014 Against Pathogenic Mold Isolated From Peach

Mold grows on peach is an important disease that harms peach production and postharvest,and has a great impact on the storage and production of peach fruit.The abuse of chemical pesticide preservatives poses a great threat to people's health,with the improvement of people's living standards.Finding safe and inexpensive anti-corrosion substitutes has become a research topic in the new era.Vinegar Pei is an important source of microdes In the process of brewing Shanxi aged vinegar.Metabolism and interaction of various microorganisms formed the unique flavor and quality of Shanxi aged vinegar.Among them,Bacillus is the most widely studied and applied.In this paper,two strains of Mold that mainly cause spoilage were isolated from moldy peaches,Two strains of Bacillus spp.isolated from Shanxi aged vinegar Pei were screened for two strains with strong bacteriostatic effect on the two strains of Mold isolated from peach,and research the antibacterial mechanism.The results are as follows:(1)Two main Pythium spp.were isolated from the mildewed peach f,Preliminary morphological observation of strains by light microscopy.Further biological identification.The results showed that the initial stage of the colony was white fluffy,and the late cystic stalk changed from transparent to light brown and light gray.The similarity ratio was 99.83%.The colony grows in the form of white flocculent at the beginning of growth,and becomes a yellow,light green-brown strain as the age of the colony increases.It has the closest affinity to Aspergillus flavus,with a similarity of 99.63%.The two strains were identified as Gilbertella persicaria isolate and Aspergillus flavus.(2)Two strains of Pythium isolated from peaches as indicator bacteria,The antibacterial screening experiments were carried out on 5 strains of spores isolated from Shanxi aged vinegar Pei by the filter pape method and the flat-panel method.The results showed that Bacillus amyloliquefaciens CP 2014,Bacillus amyloliquefaciens CP 297 and Bacillus amyloliquefaciens CP 2030 inhibited both Gilbertella persicaria MT108 and Aspergillus flavus MT106.The antibacterial effect is obvious,and the antibacterial effect of Bacillus amyloliquefaciens CP 2014 on Gilbertella persicaria MT108 is most obvious.Bacillusamyloliquefaciens CP 297 has the most obvious antibacterial effect on Aspergillus flavus MT106;Bacillus subtilis CP 1991 has a poor antibacterial effect;Bacillus licheniformis CP 1671 has no bacteriostatic effect on both strains of mold.(3)The antibacterial mechanism of the cell-free extract of Bacillus sp.was studied by measuring the conductivity,extracellular K+ concentration,extracellular AKP content,mold growth,hyphal morphology and Bacillus germination rate.The results showed that Bacillus amyloliquefaciens CP 2014 and Bacillusa trophaeus CP 297 all achieved bacteriostatic effects by changing the cell membrane permeability and cell wall of Pythium oxysporum.nder the optical microscope,the folding of Aspergillus flavus MT106 was serious.The surface of Gilbertella persicaria MT108 was rough,the hyphae became thick and thick,and the original integrity was lost.At the same time,the mycelial growth was Gilbertella persicaria MT108.0.5times;Under fluorescence microscope: CP 2014-CFE and CP 297-CFE were added to the culture medium.After 24 hours of culture,the membrane permeability of mycelium was seriously unbalanced compared with the control group,and a large amount of dye solution entered the inside of the cells.Sweeping electron microscopy can find that the bacteriostatic substance has a strong destructive effect on the cell wall and cell integrity of mold isolated from peach.(4)The bacteriostatic substance of Bacillus was applied to the application test of fresh-keeping storage of peach,and the combination of only spraying Pythium,Compound antibacterial extract(CAE)and Pythium,and calcium chloride and Pythium were researched.The impact of the shelf life,And the effect of storage on the quality of peaches at 4?and 25?.The results showed that CAE could reduce the weight loss rate of peach by about 12% compared with the control group;the activity of POD and SOD in CAE treatment group was 2% higher than that of calcium chloride and Nisin treatment group;PPO,MDA and other enzyme activities than calcium chloride Nisin treatment group is 2-5% lower;The texture mainly reflected the changes in the internal structure of the fruit.The senescence rate of peach fruit in the CAE treatment group was slower than that in the other treatment groups 2-4 d,indicating that CAE had a fresh-keeping effect on the peach.It indicated that the fresh-keeping effect of CAE on peach was better than that of commercial bacteriostatic agent Nisin and calcium chloride,and the preservation effect of single-Bacillusa bacteriostatic agent was not as good as that of Compound antibacterial extract.