Abstract:To reduce environmental contamination by aflatoxins and mitigate their threats to food security，a strain capable of degrading aflatoxin B1（AFB1）was isolated from soil through primary and secondary screening using coumarin as the sole carbon source. Based on physiological and biochemical characterization，bacterial 16S rRNA gene identification，and the construction of a phylogenetic tree，the strain was ultimately identified as Pseudomonas aeruginosa. A rapid detection kit was used to evaluate the degradation efficiency of AFB1 by the fermentation supernatant，cell lysate，and cell resuspension of the strain.The results showed that after incubation at 37 ℃for 72 h，the degradation efficiency of AFB1 in the fermentation supernatant reached 79.34%，which was the highest among all tested fractions；therefore，the active substance responsible for AFB1 degradation in P. aeruginosa was located in the fermentation supernatant. After the addition of sodium dodecyl sulfonate（SDS）and proteinase K to the fermentation supernatant，the degradation efficiency of AFB1 decreased to below 20%，indicating that the active substance in the supernatant was a protein. The factors affecting AFB1 degradation by the fermentation supernatant were further investigated. The results showed that with prolonged incubation time，the degradation efficiency reached 79.35% at 72 h；the optimal pH for degradation was 8.0，and the optimal temperature was 60 ℃. Additionally，Mn2+ and Mg2+promoted AFB1 degradation，whereas Ca2+and Fe3+inhibited the degradation process.