生物降解呕吐毒素的肠杆菌筛选与鉴定

Screening and Identification of a Deoxynivalenol-degrading Enterobacter Strain

摘要:

呕吐毒素，又名脱氧雪腐镰刀菌烯醇（deoxynivalenol，DON），主要污染小麦和大麦等作物。为了筛选得到具有呕吐毒素降解能力的菌株，实验搜集了50份土壤，通过菌株的富集、筛选和纯化得到一株白色菌株，命名为W-D，该菌株能在无机盐培养基中以DON（20 μg/mL）作为唯一碳源进行生长。对分离得到的菌株进行DON毒素降解能力检测发现，在37 ℃、180 r/min下作用于60 μg/mL的DON，经过7 d反应降解率可达40.40%。对该菌株进行相关鉴定，发现该菌株为革兰氏阴性菌，显微镜下呈短杆状，扫描电镜观察菌株为形状不一的杆状结构，大小约为0.5×(1.0~3.0) μm。生理生化鉴定结果表明W-D基本符合肠杆菌的特征。对W-D的DNA进行PCR扩增16S rDNA得到一段长度约为1500 bp的片段，测序后进行同源性分析表明该菌株属肠杆菌Enterobacter，与阴沟肠杆菌Enterobacter cloacae的亲缘关系最近。

Abstract:

The mycotoxin deoxynivalenol, also called deoxynivalenol (DON), contaminates various crops including wheat and barley. In order to identify a bacterial strain capable of DON biodegradation, a total of 50 soil samples were collected. One white strain was obtained after enrichment, screening, and purification of bacterial strains and was named W-D; it could grow in an inorganic culture medium with DON (20 μg/mL) as the sole carbon source. Analysis of DON degradation ability of the isolated bacterial strain showed that the degradation rate could reach 40.40% after the strain acted on DON (60 μg/mL) at 180 r/min for seven days at 37 ℃. Microscopic analysis showed that the strain W-D was gram-negative and had a short rod-shaped structure. Scanning electron microscopy (SEM) revealed that the strain had a rod-like structure with varying shapes, and a size of about 0.5?1.0~3.0 μm. Further analysis showed that the physiological and biochemical characteristics of W-D were essentially consistent with those of Enterobacter spp. PCR amplification of the 16S ribosomal DNA (16S rDNA) of W-D strain yielded a fragment of ~1500 bp. Subsequent phylogenetic tree analysis indicated that the strain belonged to the genus Enterobacter, and was the most closely related to Enterobacter cloacae.