Degradation of fumonisin B1 by the consecutive action of two bacterial enzymes

Abstract Detoxification of the mycotoxin fumonisin B 1 comprises at least two enzymatic steps, an initial deesterification reaction, followed by deamination of the resulting hydrolyzed fumonisin B 1 . In this study, two genes that are responsible for degradation of fumonisin B 1 by the bacterium Sphingopyxis sp. MTA144 were identified within a gene cluster, assumed to be associated with fumonisin degradation. The first gene encodes a protein which shows similarity to carboxylesterases, type B. The second gene encodes a polypeptide homologous to aminotransferases, class III. The two genes were isolated and expressed heterologously. The effect of the recombinant enzymes on fumonisin B 1 and hydrolyzed fumonisin B 1 was determined. The recombinant carboxylesterase was shown to catalyze the deesterification of fumonisin B 1 to hydrolyzed fumonisin B 1 . The heterologously expressed aminotransferase was shown to deaminate hydrolyzed fumonisin B 1 in the presence of pyruvate and pyridoxal phosphate. We propose that the consecutive action of these two enzymes is sufficient for fumonisin B 1 detoxification. The results of this work provide a basis for the development of an enzymatic detoxification process for fumonisin B 1 in food and animal feed, especially under oxygen limited conditions, as they are found, e.g. in ensilaged forage or in the intestinal tract of animals.