Research And Application Of Composite Plant Essential Oils Fungicide In The Storage Of Maize

It is easy to be contaminated by fungi and mycotoxins during the storage of maize,which poses a great threat to the health of human and livestock.Chemical synthetic fungicides are currently the main methods of protecting storage maize from fungi and mycotoxins pollution.The negative effects are varied,such as leaving high residues,high and acute toxicity,environmental pollution.Hence,eco-friendly measures are needed to be developed for all or part of alternatives which are natural,safe and efficient fungicide.As a natural antifungal agent in corn storage,the most interest has focused on the practical application of essential oils that have natural,nontoxic and antifungal properties and eco-friendly properties.But there are lack of systematic research about these essential oils to control the fungi pollution in the storage period of maize.In the present study,their synergistic effect of essential oils on the infection of fungi and contamination of mycotoxins will be useful for the potential application of the mixtures of essential oils.To investigate the changes of colony count,the structure of fungal colony fungi,the concentrations of mycotoxin and the physicochemical quality of maize during their storage,the mixtures of essential oils were used as fungicide to carry out one year experimental design in this study.According to the present design,their synergistic effect was compared with the blank control group and propionic acid treatment group.The major conclusions of our study are summarized as follows:1.Maize were selected for the raw material which were bought in the fall of 2016.Samples were collected every month to observe the variation patterns of microflora on the maize.As showing by the results,the total fungal count tended to increase firstly and then decreased during their storage.At the end of eighth month,the total number of colonies in blank control group reached the maximum value of1449.3 cfu/g.The inhibition rate of essential oils and propionic acid on the total number of fungi was88.96%and 71.7%,respectively.The results indicate that their synergistic effect of essential oils on the prevention and control of fungi infection was stronger than the treatment of propionic acid.2.As shown in the Isolation and identification of fungi,Aspergillus flavus,Penicillum and Aspergillus glaucus were primarily isolated from maize sample.After treatment of essential oils,the colonies of Aspergillus flavus and Fusarium were decreased by 99.4%and 100%,respectively.In the group of propionic acid,the strains were decreased by 82.6%and 100%,respectively.Compared with propionic acid,composite plant essential oils could inhibit significantly fungical growth.3.The results of LC-MS/MS showed that,AFB₁、DON were the main mycotoxins during maize storage,the highest contents were 21.14 ng/g、640.17 ng/g after in the end of 8th month of storage.The contents of 2 mycotoxins reduced obviously after the treatment of essential oils and propionic acid,the inhibition rates of essential oils were 90.6%、66.0%,and the inhibition rates of propionic acid were93.0%、88.0%.4.The total DNA of fungi on the surface of maize samples would be used to amplify the ITS2region of rDNA and analysised by the technology of next generation sequencing.The results of this study revealed that Ascomycota was the most popular species of fungi,accounting for more than 70%,during the 12 months storage time.After treatment of essential oils,the average relative abundance of Ascomycetes were decreased.And the average relative abundance of Wallemia was increased slightly,that of Aspergillus and Fusarium were all decresed.These results showed that the essential oils can prevent mildew of maize by inhibiting the growth of Aspergillus and Fusarium.5.After treatment of essential oils,it would be about 85.0%.Meanwhile,Essential oil can inhibit the spoilage of maize,it was only about 35.2 mgKOH/100g.That treatment can protect the physiological activity of maize from spoiling,but the treatment of propionic acid cannot.In summary,their synergistic effect of essential oils on the prevention and control of fungi infection and mycotoxins contamination was stronger than the treatment of propionic acid.The results of this study indicate that essential oil can be a kind of efficient and quality fungicide with its wide-spread applicability.