Role of Toxin Concentration and Second Carbon Source in Microbial Transformation of Aflatoxin B1 by Flavobacterium aurantiacum

Abstract

The aflatoxins are toxic and carcinogenic mycotoxins which contaminate a variety of foods and feeds. The bacterium Flavobacterium aurantiacum NRRL B-184 has been previously shown to be effective in degrading aflatoxin B1) in liquid test medium as well as in several food types. The purpose of this study was to investigate the effects of an added nutrient source and added aflatoxin on the ability of F. aurantiacum to degrade aflatoxin B1. Radioactively labeled aflatoxin B1 was added to test solutions containing cells in phosphate buffer or tryptic soy broth. Nonlabeled aflatoxin B1 was also added to similar flasks. Analysis of radioactive CO2 and water- and chloroform-soluble portions of the cell supernatant fluids revealed that neither added nutrients nor added nonlabeled toxin had a significant influence on the microbial transformation of aflatoxin B1 These results suggest that the microbial degradation of aflatoxin by F. aurantiacum is probably a mineralization phenomenon and not a co-metabolism. The ability of this organism to detoxify aflatoxin without the need for exogenous energy sources could be important to future endeavors attempting to use the organism, or the mechanisms responsible, in fermentation reactions.