Biotransformation and detoxification of aflatoxin B1 by extracellular extract of Cladosporium uredinicola.

Aflatoxin contamination of food and grain poses a serious economic and health problem globally. Aflatoxin B1 (AFB1) is extremely mutagenic and toxic as well as a potent carcinogen to both humans and livestock. In this study, the degradation of AFB1 by extracellular extract of Cladosporium uredinicola was examined using high-performance liquid chromatography (HPLC), thin-layer chromatography (TLC), and liquid chromatography mass spectrometry. Within 24 h of incubation, AFB1 was efficiently eliminated by the culture supernatant of C. uredinicola (84.5±5.7%) at 37°C; the elimination was proven to be enzymatic, and the enzyme was thermostable. The biotransformation products of AFB1 detected by HPLC and TLC were proven to be the same compound. Analysis with LCMS showed that AFB1 was bio-transformed to a structurally different compound (m/z=365 [M+Na]+), which is first reported. The cytotoxicity study to HeLa cells indicated that culture supernatant-treated AFB1 is less toxic as compared with AFB1.