枯草芽孢杆菌Natto3的筛选及其降解黄曲霉毒素B_1的初步研究

从可食用的纳豆中筛选出一株能够高效降解黄曲霉毒素B1(aflatoxin B1,简称AFB1)的细菌,该细菌的发酵上清液经浓缩后制成的粗酶液对AFB1降解率达到91.4%。对该菌进行了分类地位鉴定并初步研究了粗酶液的酶学性质。结果表明,该菌经生理生化和16S r DNA序列比对鉴定为枯草芽孢杆菌,并命名为Natto3。Natto3的粗酶液降解AFB1的最适培养时间为72h,最适反应温度为37℃,最适p H值是8.5,Zn2+、Mn2+、Mg2+、Cu2+、Li+五种金属离子均会不同程度地抑制降解活性。此外,将该粗酶液添加在被黄曲霉毒素高度污染的花生样品中进行脱毒实验,可使花生中AFB1的浓度从192μg/kg降至43μg/kg。

Study on isolation and degradation of aflatoxin B1 of Bacillus Natto3

An unknown bacterial strain was isolated from the edible natto and this strain could effectively degrade aflatoxins B1 (AFB1). The degradation rate of AFB1 could reach 91.4% with the concentrated crude enzyme solution prepared from the fermented supernatant. The strain was then taxonomic status identified and enzymatic properties of crude enzyme were investigated. Results were listed as follows: this strain was identified as Bacillus subtilis based on physiological, biochemical and 16S rDNA sequence analyses, thus named as B. subtilis sp. Natto3. The optimal growth time, reaction temperature, and pH value for the degradation of AFB1 by crude enzyme solution were 72h, 37℃ and 8.5 respectively; the degradation activity could be inhibited to different extents by 5 metal ions including Zn2+, Mn2+, Mg2+, Cu2+ and Li+. Furthermore, we added the crude enzyme solution into the peanut sample highly contaminated by AFB1, and examined whether AFB1 could be degraded. Detoxification experiment showed that AFB1 content in the contaminated peanut samples was decreased from 192μg/kg to 43μg/kg by the crude enzyme solution prepared from the culture of B. subtilis sp. Natto3.