Screening The Bacteria For The Degradation Of Deoxynivalenol And Structure Identification Of Its Degradation Product

Deoxynivalenol(DON),a type of B-group trichothecenes,is a mycotoxin produced by Fusarium after infecting wheat and other grains.DON displays high cytotoxicity due to inhibitting protein synthesis by combining with ribosome.Once take excessive DON contained in food,humans and animals will suffer acute poisoning symptoms,even death,therefore the food and feed polluted by DON lose the edible value,causing huge economic losses.In this study,all the strains stored in our were screened againt DON to assess their capacity for DON degradation.Furthermore,we explored optimal conditions of DON degradation,and the degradation products were also analyzed.The main results are summarized as follows:In order to obtain a large quantity of DON for detoxification research,we developed a simple,economic and efficient method of DON separation and purification by liquid-liquid extraction and HPLC with rice as the production medium.This method can obtain DON with a purity of more than 80% without any column chromatography.After the preparation of liquid-phase purification,we can directly obtain DON pure product.With this method,61.4 mg DON pure product was obtained from 1 kg rice culture.145 strains in total preserved in our laboratory were screened for their capacity of DON degradation.Among them,HN-117 was identified as the optimal candidate,which showed 19.7±1.3%.DON degradation in screening condition.At early stage of growth,the colony suface of HN-117 was smooth,light yellow,and regular shape.At late stage,it showed wrinkled and irregular shape.HN-117 was determined as Bacillus subtilis by 16 S rDNA method.The parameters for degradation of DON by HN-117,e.g.,degradation process,optimum temperature and optimum concentration of DON,were studied systemically.The results reavealed that optimal time and temperature for the degradation of DON mediated by HN-117 were for four days and 30?C.29.5% ~ 44.5% degradation rate mediated by HN-117 was achieved under lower concentration of DON(100 ?g/ml),while it decreased to 25.1% ~ 29.5% once the concentration of DON surpassing 100 ?g/ml.Semi-preparative scale reaction for DON conversion was performed,and the product M-DON was obtained DON for structure analysis based on UPLC-qTof-MS and ~1H-NMR.The results proved that M-DON was the isomer of DON,because of ether bond breaking and rearrangement ether bond between C2,C11 and between C12,C13.