Detoxification of aflatoxin B1 by Bacillus aryabhattai through conversion of double bond in terminal furan.

Aims This study aimed to screen a bacterial strain with high detoxifying capability for aflatoxin B₁ (AFB₁), verify its biotransformation efficiency, and detoxification process. Methods and results A total of 350 samples collected from different environmental niche were screened using coumarin as the sole carbon source. High Performance Liquid Chromatography (HPLC) was used to detect residues of AFB₁, and 16S rRNA sequencing was performed on the isolated strain with the highest AFB₁ removal ratio for identification. The detoxified products of this strain were tested for toxicity in Escherichia coli as well as LO2, Caco-2, and HaCaT human cell lines. HPLC-MS was applied to further confirm the AFB₁ removal and detoxification process. Conclusions We identified a strain from plant leaf designated as DT with high AFB₁-detoxifying ability that is highly homologous to Bacillus aryabhattai. The optimum detoxification conditions of this strain were 37°C and pH 8.0, resulting in 82.92% removal ratio of 2 μg mL⁻¹ AFB₁ in 72 h. The detoxified products were nontoxic for E. coli and significantly less toxic for the LO2, Caco-2, and HaCaT human cell lines. HPLC-MS analysis also confirmed the significant drop of the AFB₁ characteristic peak. Two possible metabolic products, C₁₉H₁₅O₈ (m/z 371) and C₁₉H₁₉O₈ (m/z 375), were observed by mass spectrometry. Potential biotransformation pathway was based on the cleavage of double bond in the terminal furan of AFB₁. These generated components had different chemical structures with AFB₁, manifesting that the attenuation of AFB₁ toxicity would be attributed to the destruction of lactone structure of AFB₁ during the conversion process. [ABSTRACT FROM AUTHOR]