黄曲霉毒素B1降解菌的筛选鉴定及降解酶挖掘

目的 筛选、鉴定一株高效降解黄曲霉毒素B1 (aflatoxin B1, AFB1)菌株，并对其降解特性和降解酶基因进行分析。方法 通过形态学观察、生理生化鉴定及同源性分析，对具有高效降解AFB1能力的菌株进行鉴定。通过菌株发酵液、上清液、细胞悬液、胞内提取物对AFB1降解能力的不同确定降解活性部位，使用冷冻干燥方法探索其粗酶制剂对AFB1降解效果。结合全基因组分析进行降解酶基因的挖掘。结果 通过鉴定，菌株HNGD-B3为贝莱斯芽孢杆菌(Bacillus velezensis)，菌株上清液对AFB1降解效果最好，72 h降解率为88.24%±2.02%。上清液蛋白酶K处理后，对AFB1降解效果大幅下降，热处理后上清液降解效果基本无变化，判断其降解活性成分为胞外酶。粗酶制剂可显著提高AFB1降解效率，结合全基因组分析与Blastp比对筛选得到3条具有AFB1降解潜力的候选基因序列。结论 菌株HNGD-B3对AFB1具有良好降解效果，在生物降解真菌毒素具有较大潜力。

Screening and identification of aflatoxin B1 degrading bacteria and digging of degrading enzymes

Objective To screen and identify a strain that can effectively degrade aflatoxin B1 (AFB1), and analyze its degradation characteristics and degrading enzyme genes. Methods The strains with the ability to degrade AFB1 efficiently were identified by morphological observation, physiological and biochemical identification and homology analysis. The active site of AFB1 degradation was determined by the difference of AFB1 degradation ability of strain fermentation broth, supernatant, cell suspension and intracellular extract, and the effect of its crude enzyme preparation on AFB1 degradation was explored using freeze-drying method. Preliminary mining of degradation enzyme genes combined with whole genome analysis. Results The strain HNGD-B3 was identified and screened as Bacillus velezensis, and the 72 h supernatant of the strain had the best degradation effect on AFB1 with 88.24%±2.02%. The degradation rate of AFB1 by supernatant decreased significantly after treatment with proteinase K. The degradation effect of supernatant was basically unchanged after heat treatment, and the degradation active component was judged to be extracellular enzyme. The crude enzyme preparation could significantly improve the AFB1 degradation efficiency, and 3 candidate gene sequences with AFB1 degradation potential were obtained by combining genome-wide analysis with Blastp screening. Conclusion The strain HNGD-B3 has good degradation effect on AFB1 and has a greater potential in biodegradation of fungal toxins.