1株伏马毒素B_(1)降解真菌的筛选及降解特性分析

Screening and Degradation Characteristics of a Fumonisin B_(1)-Degrading Fungal Strain

为筛选能够降解伏马毒素B_(1)(fumonisin B_(1),FB_(1))的真菌,将伏马毒素污染严重的玉米样品磨碎处理,采用富集培养的筛菌方法获得目的菌株,将所得菌株命名为FDS-2,对其进行菌种鉴定、生长特性与降解特性分析,并探究该菌株对FB_(1)的初步降解途径。根据FDS-2的培养特征、显微特征以及rRNA-ITS序列特征构建的系统进化树,该菌被鉴定为棘状外瓶霉(Exophiala spinifera)。菌株的最适生长与降解条件为30℃、pH 5.0,在此条件下,菌株可在48h内将250μg的FB_(1)降解完全。通过降解物质定位实验,确定FDS-2中降解活性物质是位于细胞内的降解酶。使用液相色谱-质谱分析降解产物,确定初步降解途径为FDS-2首先把FB_(1)降解成为水解FB_(1)。本研究为粮食和饲料中伏马毒素的生物降解提供了菌种资源和理论基础。

A fungal strain capable of degrading fumonisin B_(1)(FB_(1))from ground maize samples heavily contaminated with fumonisin was obtained by enrichment culture method.The strain was named as FDS-2,and was characterized for its growth and degradation characteristics,and the initial degradation pathway of FB_(1) by FDS-2 was investigated.The strain was identified as Exophiala spinifera according to its culture characteristics,microscopic characteristics and phylogenetic tree based on RNA-internal transcribed spacer(ITS)sequence characteristics.The optimum growth and degradation conditions were 30℃and pH 5.0.Under these conditions,the strain could completely degrade 250μg of FB_(1) within 48 h.Intracellular FB_(1)-degrading enzymes were discovered in this strain.Using liquid chromatography-mass spectrometry(LC-MS)to analyze the degradation products,it was determined that the primary degradation pathway began with the degradation of FB_(1) into hydrolyzed FB_(1).This study provides a strain resource and a theoretical basis for the biodegradation of fumonisin in grain and feed.