Zhang Wei, Xue Beibei, Li Mengmeng, Mu Yang, Chen Zhihui, Li Jianping, Shan Anshan
Institute of Animal Nutrition, Northeast Agricultural University, Harbin 150030, China.
Toxins (Basel). 2014 Nov 13;6(11):3157-72. doi: 10.3390/toxins6113157.
Aflatoxin B₁, a type of highly toxic mycotoxin produced by some species belonging to the Aspergillus genus, such as Aspergillus flavus and Aspergillus parasiticus, is widely distributed in feed matrices. Here, coumarin was used as the sole carbon source to screen microorganism strains that were isolated from types of feed ingredients. Only one isolate (ND-1) was able to degrade aflatoxin B₁ after screening. ND-1 isolate, identified as a strain of Aspergillus niger using phylogenetic analysis on the basis of 18S rDNA, could remove 26.3% of aflatoxin B₁ after 48 h of fermentation in nutrient broth (NB). Optimization of fermentation conditions for aflatoxin B₁ degradation by selected Aspergillus niger was also performed. These results showed that 58.2% of aflatoxin B₁ was degraded after 24 h of culture under the optimal fermentation conditions. The aflatoxin B₁ degradation activity of Aspergillus niger supernatant was significantly stronger than cells and cell extracts. Furthermore, effects of temperature, heat treatment, pH, and metal ions on aflatoxin B₁ degradation by the supernatant were examined. Results indicated that aflatoxin B₁ degradation of Aspergillus niger is enzymatic and this process occurs in the extracellular environment.
黄曲霉毒素B₁是由某些曲霉属物种（如黄曲霉和寄生曲霉）产生的一种剧毒霉菌毒素，广泛分布于饲料基质中。在此，香豆素被用作唯一碳源，以筛选从各类饲料原料中分离出的微生物菌株。筛选后，只有一株分离株（ND-1）能够降解黄曲霉毒素B₁。基于18S rDNA的系统发育分析将ND-1分离株鉴定为黑曲霉菌株，该菌株在营养肉汤（NB）中发酵48小时后可去除26.3%的黄曲霉毒素B₁。还对筛选出的黑曲霉降解黄曲霉毒素B₁的发酵条件进行了优化。这些结果表明，在最佳发酵条件下培养24小时后，58.2%的黄曲霉毒素B₁被降解。黑曲霉上清液对黄曲霉毒素B₁的降解活性明显强于细胞和细胞提取物。此外，还研究了温度、热处理、pH值和金属离子对上清液降解黄曲霉毒素B₁的影响。结果表明，黑曲霉对黄曲霉毒素B₁的降解是酶促反应，且该过程发生在细胞外环境中。
