Biological degradation of aflatoxin B1 by Rhodococcus erythropolis cultures

Aflatoxin contamination of food and grain poses a serious economic and health problem worldwide, but particularly in Africa. Aflatoxin B1 (AFB1) is extremely mutagenic, toxic and a potent carcinogen to both humans and livestock and chronic exposure to low levels of AFB1 is a concern. In this study, the biodegradation of aflatoxin B1 (AFB1) by Rhodococcus erythropolis was examined in liquid cultures using thin layer chromatography (TLC), high performance liquid chromatography (HPLC), electro spray mass spectrometry (ESMS) and liquid chromatography mass spectrometry (LCMS). AFB1 was effectively degraded by extracellular extracts from R. erythropolis liquid cultures. Results indicated that the degradation is enzymatic and that the enzymes responsible for the degradation of AFB1 are extracellular and constitutively produced. Furthermore, the biodegradation of AFB1 when treated with R. erythropolis extracellular fraction coincided with a loss of mutagenicity, as evaluated by the Ames test for mutagenicity.