Functional Characterization and Whole-Genome Analysis of an Aflatoxin-Degrading Strain.

Aflatoxin B (AFB) is one of the most toxic, naturally occurring carcinogen compounds and is produced by specific strains of fungi. Crop contamination with AFB can cause huge economic losses and serious health problems. Many studies have examined the microbiological degradation of AFB, especially the use of efficient AFB-degrading microorganisms, to control AFB contamination. Here, we reported the identification of a new strain (4-4) that can efficiently degrade AFB (degradation rate 84.9%). The extracellular component of this strain showed the strongest capacity to degrade AFB (degradation rate 83.7%). The effects of proteinase K, SDS, temperature, pH, incubation time, and AFB concentration on the AFB degradation ability of the extracellular component were investigated. We sequenced the complete genome of this strain, encoding 5246 protein-coding genes and 169 RNA genes on a circular chromosome and two plasmids. Comparative genomic analysis revealed high homology with other strains with high AFB-degradation ability. Further proteomic analyses of this strain identified a total of 723 proteins in the extracellular component, including multiple potential AFB-degrading enzymes, along with enzymes that are reported to response to AFB treatment. Overall, the results demonstrate that 4-4 would be an excellent candidate for the biodegradation and detoxification of AFB contamination.