Characterization and genomic analysis of Bacillus megaterium with the ability to degrade aflatoxin B1

Coix seed is a good product for both medicinal and food use, which is highly susceptible to aflatoxin B 1 (AFB 1 ) contamination during field transport, storage, and processing. The aim of this study is to find microbial strains that can solve the problem of contamination of coix seed. In this study, the AFB 1 -degrading microorganism SX1-1 was isolated and identified as a Bacillus megaterium based on morphology, microscopy, and 16S rDNA sequencing. The optimum culture conditions for SX1-1 to degrade AFB 1 were determined to be 12 h. The optimum degradation conditions were 72 h, 57°C, and an initial pH of 8.0. The highest degradation of AFB 1 was observed in the fermentation supernatant of the SX1-1 strain, with a degradation rate of 97.45%. In addition, whole-genome sequencing analysis of this strain revealed the presence of a number of enzymes that could potentially degrade AFB 1 . Importantly, SX1-1 was able to degrade AFB 1 -contaminated coix seed in situ by 50.06% after co-culture. In conclusion, this strain had a high AFB 1 degradation ability, and has great potential and great application as a biocontrol agent for AFB 1 degradation of coix seed.