复合菌系降解黄曲霉毒素B_1的效果及组成多样性研究

采用"外淘汰法"筛选了一组对黄曲霉毒素B_1(aflatoxin B_1,AFB_1)具有高效降解能力的复合菌系FBAD-2,该复合菌系在120 h内能将质量浓度为2 000μg/L的AFB_1完全降解,对质量浓度为5 000μg/L的AFB_1能降解90%。FBAD-2在30~70℃的范围内均能保持对AFB_1的高效降解能力,其最适温度为60℃。毒素降解实验分析表明,FBAD-2对AFB_1的降解主要是胞外酶的作用,其最适产酶时间为24 h,此时的胞外粗酶液在48 h内能将5 000μg/L的AFB_1完全降解。16S rDNA基因组测序分析结果表明,FBAD-2的微生物组成主要包括土芽孢杆菌(Geobacillus)、嗜热小杆菌(Symbiobacterium thermopilum)、梭菌(Clostridium)和热厌氧杆菌(Tepidanaerobacter)等。

Degradation of Aflatoxin B1 by a Microbial Consortium and Its Composition and Diversity

External elimination method was applied to obtain an efficient aflatoxin B1-degrading microbial consortium, designated FBAD-2. The degradation rates of 2 000 and 5 000 μg/L AFB1 by the microbial consortium could reach 100% and 90% within 120 h, respectively. The toxin degradation ability of FBAD-2 was kept at a high level in the range of 30–70 ℃, with an optimal temperature of 60 ℃. The results of AFB1 detoxification experiment showed that the extracellular enzymes in the supernatant played a major role in the degradation of AFB1. Furthermore, the optimal culture time for enzyme production was 24 h, and the supernatant could completely degrade 5 000 μg/L AFB1 within 48 h. 16S rRNA gene clone library analysis showed that FBAD-2 was mainly composed of bacteria from the genera Geobacillus, Symbiobacterium thermopilum, Clostridium and Tepidanaerobacter.