Preliminary evidence that degradation of aflatoxin B1 by Flavobacterium aurantiacum is enzymatic

The ability of crude protein extracts from Flavobacterium aurantiacum to degrade aflatoxin B1 (AB1) in aqueous solution was evaluated. Crude protein extracts (800 microg of total protein per ml) degraded 74.5% of AB1 in solution. An average of 94.5% of AB1 was recovered after incubation with heat-treated crude protein extracts (800 microg of total protein per ml). DNase I-treated crude protein extracts degraded 80.5% of AB1 in solution, suggesting that removal of aflatoxin by F. aurantiacum is not due to nonspecific binding with the bacterium's genomic DNA. Proteinase K-treated crude protein extracts degraded 34.5% of AB1, providing evidence that degradation of aflatoxin is linked to a protein that is possibly an enzyme. Solution pH affected the amount of AB1 degraded by crude protein extracts after 24 h. Maximum degradation was observed at pH 7 (pH levels tested: 5, 6, 7, and 8), with some AB1 degradation occurring at pH levels as low as 5 and as high as 8. Acidic pH levels were more detrimental to the ability of crude protein extracts to degrade AB1 than was basic pH. The results of this work indicate that the degradation of AB1 by F. aurantiacum may be enzymatic.