IDENTIFICATION OF A VARIANT OF FUSARIUM-PROLIFERATUM THAT HYDROLYZES FUMONISIN B-1

Fumonisins are mycotoxins produced primarily by Fusarium moniliforme a nd Fusarium proliferatum in corn. Normally, the fumonisins display con siderable chemical stability at temperatures up to 100 degrees C at ne utral pH and are stable in a pH range of 4-10 at ambient temperature. Fumonisin B-1 (FB1) can be produced in bioreactors using F. proliferat um (M5991). Recently, some bioreactor-grown cultures of F. proliferatu m were found to rapidly hydrolyze FB1. Subcultures from stock frozen f rom these FB1-degrading variants continued to degrade FB1 when grown u nder the same bioreactor conditions. The initial hydrolysis was cataly zed by an esterase and resulted in the appearance of the aminopentol b ackbone (AP(1)) of FB1. A cell-free extract retaining the FB1 hydrolyt ic activity could be obtained by extraction of cell paste with 10% Tri ton X-100. Activity could be destroyed by heating to 60 degrees C for 5 min or by the addition of acetonitrile.