A Study Of The Optimization Condition Of Epoxide Hydrolase Producing By NJA-1 Strain And Its Biotransformation For Deoxynivalenol

Mycotoxins were toxic secondary metabolites produced by fungi(molds),which widely contaminated raw material and finished product.It would result in mycotoxins poisoning.Deoxynivalenol(DON) is a type of harmful mycotoxin produced by Fusarium graminearum Schwabe.DON contamination in harvested grain can significantly lower market grade,and result in significant discount in price to the farmers.Recent study indicated that the enzyme could removed of the toxicity of toxin by decomposing Mycotoxicoses into innoxious metabolites.Epoxide hydrolase could decompose epoxy groups of Toxin Molecular of Tichothecenes.The enzyme could reduce the production of toxins by degradation of mycotoxins of metabolites or change their molecular structures into innoxious substances.The aim of the experiment was to optimize of the condition of producing epoxide hydrolase and study the enzymology property of epoxide hydrolase and its biotransformation of DON.Testâ… The optimization condition of producing the epoxide hydrolaseA strain was isolated from soil and identified as NJA-1 by our laboratory.The strain showed an activity of epoxide hydrolase and could biotransform DON.The purpose of the test was investigated the optimized conditons for enzyme production.It found that high enzyme activity was achieved when 1.0%corn extract and 1.0%glucose were used as carbon and nitrogen sourced,respectively,at optical initial pH 4.0,optical temperature 30℃for 32h.in addition,the Ca²⁺ and Mg²⁺ colud promote the activity of the epoxide hydrolase.Testâ…¡Preliminariy study on the enzymatic properities of epoxide hydrolaseThe aim of the test was to produce extract EH using the NJA-1 stain,and to study the character of the epoxide hydrolase.Reaserch of enzymatic properties showed that the optimal temperature and pH were 30℃and 7.0.The epoxide hydratase activity is stable between temperature 25～40℃and between pH 6.0～9.0.The Mg²⁺ and Ca²⁺ could promote the activity of the epoxide hydrolase and the organic solvent DMSO also colud slightly promote the activity of the epoxide hydrolase.Testâ…¢The transformation of DON by thallus and extracted enzymeWe added thalli and extraction enzyme and EH enzyme into different concentration of DON(4μg/ml,8μg/ml,20μg/ml,100μg/ml).After reaction at 30℃,the content of DON is detected by high performance liquid Chromatogram(HPLC).The results of HPLC showes that the product was absorbent at wave length 218nm. The detection of product of the deoxynivalenol biotransformation by the thalli,extract enzyme and EH enzyme.Compared with the thalli before optimization,the thalli after optimization increase the conversion of DON by 11.2%.The extract enzyme and EH enzyme also could significantly biotransform DON to several products.Compared extraction enzyme and EH enzyme,the time and number of the UV absorbing peak of the products is basically identical showed by HPLC.