Isolation And Identification Of AflatoxinB1 Degrading Bacteria

AflatoxinB1 is a one of the most common mycotoxins,It has been shown to be great toxic,carcinogenic and cause severe environment pollution.Aflatoxin contamination causes great economic loss in animal husbandry and feed industry.Therefore,It is very important to develop methods to inactive,destroy,or remove aflatoxin from feed products.Biodegradation is one of efficient,practical,and environmentally friendly decontamination methods.The aim of this study was to isolate and identify microbe strains that could effectively degrade aflatoxin B1.The first part of the thesis,During the experiment,eight strains of microbe were isolated from soil,sour gruel,rumen liquid,grape skin,and maize straw.Among them,four strains were isolated from soil,and the other four strains were isolated from sour gruel,rumen liquid,grape skin and maize straw.The microbe strains were named K,K1,K2,J,M,JW,JL,and JP,respectively.The second part of the thesis,According to the bacterial morphological,physiological and biochemical characteristics,and 16 SrDNA sequences homology comparison,the eight isolated unknown microbe strains were identified.The results showed that the microbe strain K was Bacillus amyloliquefaciens with 16 SrDNA Gene-bank accession NO.KX682280,the microbe strain K1 was Baclicus lincheniformis with the Gene-bank accession NO.KJ538552,the microbe strain K2 was Baclicus megaterium with the Gene-bank accession NO.MF4177448,the microbe strain J was Aeromonas caviae with the Gene-bank accession NO.X60409,the microbe strain M was Lactobacillus fermentation with the Gene-bank accession NO.MG551079,the microbe strain JP was Enterococcus faecalis with the Gene-bank accession NO.MF582338,the microbe strain JW was Enterococcus hirae with the Gene-bank accession NO.MF327681;the microbe strain JL was Lactococcus lactis with the Gene-bank accession NO.MG754677.The third part of the thesis,The aflatoxin degradation ability of the 8 isolated microbe strains and other 9 strains from our lab were assayed.first we screened microbes by culturing them in the medium with coumarin as sole carbon source.Coumarin is the structure analogue of aflatoxin.After this,we assayed degradation ability of these microbe by using AFB1 standard product.The ELISA assay was used to determine the AFB1 concentration and the degradation rate was calculated.The results were as follow: nine microbe strains(S1,S14,K,JP,K1,JW,M,JL,C)showed better degradation rate.The degradation ratios were as follow: 88%,64.92%,62.83%,59.12%,55.92%,54.93%,52.50%,52.32%,47.19%,respectively.