Study On The Preparation Of A New Biological Antidote And Its Detoxification Mechanism For Aflatoxin B₁

Aflatoxin B₁（Aflatoxin B₁,AFB₁）is the most toxic and hepatocarcinogenic among the known mycotoxins.How to quickly and safely is the difficulty of current research.This topic was based on the detoxification effect of AFB₁by adsorption and degradation methods.Firstly,the difference in detoxification of various porous adsorbent materials was studied,and the core-shell composite material ZIF-8-MSN-NH₂with the best detoxification effect was selected as the first choice of adsorbent.Then,by comparing the detoxification effects of laccase,Aspergillus niger crude enzyme and compound enzyme preparations on AFB₁,the best enzyme combination for biodegradation of AFB₁was determined.Finally,a novel biological antidote with a core-shell structure was designed with the synergistic effect of degradation and adsorption methods.The novel biological antidote selected the adsorption material with the best detoxification effect and combines with the compound enzyme preparation,and realized the efficient removal of AFB₁by the adsorption of the material and the degradation of the enzyme.The detoxification method of this novel biological antidote was a multi-functional joint removal process of adsorption enrichment followed by biodegradation.The first was to use the material to realize the adsorption of toxin,and then enrich the toxin for the internal natural enzyme,improve the local toxin concentration around the biological enzyme,and finally improve the degradation rate of the enzyme.Compared with the adsorption of a single porous material and the degradation of the composite enzyme preparation,the new biological detoxifier,a detoxification method that combines adsorption and degradation,can avoided the limitation of adsorption capacity to a certain extent,and the difficulty of enzyme recycling and reuse.Specific research contents and results were as follows:（1）ZIF-8-MSN-NH₂composite material showed the best adsorption effect,the adsorption capacity of AFB₁can reach 740.216μg/g,and can realize the rapid detoxification of AFB₁in 90 min.At the same time,the core-shell nanocomposite had good reusability,and the adsorption effect of AFB₁was still 64.57%after 5 times.The detoxification effect of ZIF-8-MSN-NH₂composite mainly depended on the adsorption of the material.（2）The composite enzyme preparation showed the best degradation effect,and can degrade 64.54%of the AFB₁toxin within 24 h under the best enzyme ratio（laccase:Aspergillus niger crude enzyme=4:2）.The degradation rate of AFB₁by the compound enzyme preparation was as high as 67.45%,which was 65.78%higher than the degradation rate of Aspergillus niger crude enzyme.Compared with laccase,the degradation rate of AFB₁was increased by 19.24%.The compound enzyme preparation had the highest detoxification rate of 64.50%at 35℃.The two enzymes had different degradation sites for AFB₁.（3）The new biological antidote had excellent detoxification effect on AFB₁,and the molecular formula of its detoxification product was C₁₅H₁₄O₂.The novel biological antidote achieved degradation by destroying the C-O bond of AFB₁.There were two detoxification ways in the detoxification process of the novel biological antidote:adsorption and degradation.The detoxification effect of the new biological antidote was superior to that of ZIF-8-MSN-NH₂and compound enzyme preparation.By comparing the difference of detoxification effect of the new biological antidote before and after inactivation,it was confirmed that the main reason for the efficient detoxification of the new biological antidote was the adsorption advantage of ZIF-8-MSN-NH₂material and the combined degradation of the compound enzyme preparation.In the new biological antidote,ZIF-8 shell acted as the adsorbent of AFB₁,which increased the local toxin concentration around the compound enzyme preparation,and the two biological enzymes inside can play the role of compound degradation.Secondly,this special core-shell structure was conducive to the stability of the antidote in the application process.The results showed that the detoxification rate of the new biological antidote to AFB₁standard was 98.07%under the condition of 35℃and 36 h.At30℃,the new biological antidote degraded 83.59%AFB₁within 24 hours.Therefore,combined with the actual grain storage conditions,30℃was selected as the detoxification temperature.The detoxification rate of the new biological antidote to actual moldy corn was75.75%.The total immobilization efficiency（E）of laccase and Aspergillus niger in the new biological antidote was 89.55%.The kinetic model showed that the Michaelis constant（Km）of the new biological antidote was 5.5×10^-5mol/L,which was higher than that of the free compound enzyme.When the new biological antidote was stored at 4℃for 30 days,the enzyme activity of the new biological antidote was still 70.85%of the initial enzyme activity.The enzyme activity of the new biological antidote was 80.73%after 4 experiments.After 4experiments,the detoxification rate of AFB₁was still as high as 87.86%,which had high practical application value.