一株黄曲霉毒素B_1降解菌的筛选及鉴定

以香豆素为唯一碳源进行AFB1降解菌的初筛,从青岛土壤中筛选出高效降解AFB1的菌株A6,分离该菌的上清液、菌悬液、胞内液并分析各组分降解AFB_1特征,通过形态学、生理生化和16S rRNA基因对该菌株进行鉴定。研究结果表明,菌株A6能高效降解AFB1,其胞外上清液、菌悬液和胞内液能分别降解90.6%、19.6%和12.8%的AFB_1,表明起降解的活性物质主要位于胞外液。在平板上该菌落呈现乳白色,具有皱褶,革兰氏染色呈阳性;能利用葡萄糖、阿拉伯糖、乳糖等碳源; 16S rRNA基因分析表明该菌与贝莱斯芽孢杆菌CR-502~T(Bacillus velezensis)相似度为99.64%。综合形态学特征、生理生化特征和16S rRNA基因分析结果,鉴定菌株A6为贝莱斯芽孢杆菌(Bacillus velezensis),命名为Bacillus velezensis A6。本研究结果为深入研究该菌的降解机理奠定了基础。

Screening and Identification of Aflatoxin B_1 Degradation Strain

The degradation bacteria were isolated from the soil in Qingdao by screening with coumarin as the only carbon source,and the highly efficient strain A6 was further identified.The supernate,bacterium suspension and intracellular fluid of the strain A6 were separated and the degradation characteristics of AFB 1 were analyzed. The strain was identified by morphological characteristics,physiological,biochemical characteristics and 16S rRNA gene.The results indicated that the strain A6 could efficiently degrade AFB 1 .The supernate,bacterium suspension and intracellular fluid could degrade 90.6%,19.6% and 12.8% of AFB 1 ,suggesting that the degradation activity of strain A6 was located in extracellular fluid.On the plate,the strain colony was milky white with wrinkles and gram stain was positive.The strain could assimilate glucose,arabinose,lactose and other carbon sources.Analysis of the 16S rRNA gene showed that the similarity between strain A6 and Bacillus velezensis CR-502 T was 99.64%.Based on the morphology,physiological and biochemical characteristics,and the analysis of 16S rRNA gene sequence homology,the strain A6 was identified as Bacillus velezensis.The results provided a foundation for further study on the degradation mechanism of this bacterium.