Identification and Characterization of an Aspergillus niger Amine Oxidase that Detoxifies Intact Fumonisins

Abstract

Fumonisin contamination of maize damaged by Fusarium verticillioides and related species is a major problem when it is grown under warm and dry conditions. Consumption of fumonisin contaminated food and feed is harmful to both humans and livestock. Novel tools for reducing or eliminating fumonisin toxicity may be useful to the agri-feed sector to deal with this worldwide problem. Enzymes capable of catabolizing fumonisins have been identified from microorganisms that utilize fumonisins as an energy source. However, fumonisin detoxifying enzymes produced by the very species that biosynthesize the toxin have yet to be reported. Here we describe the identification and characterization of a novel amine oxidase synthesized by the fumonisin-producing fungus Aspergillus niger. We have recombinantly expressed this A. niger enzyme in E. coli and demonstrated its ability to oxidatively deaminate intact fumonisins without requiring exogenous cofactors. This enzyme, termed AnFAO (A. niger fumonisin amine oxidase), displays robust fumonisin deamination activity across a broad range of conditions, has a high native melting temperature, and can be purified to >95% homogeneity at high yield in a one-step enrichment. AnFAO is a promising tool to remediate fumonisin-contaminated feed including maize destined for ethanol production.

Keywords: Aspergillus niger; Mycotoxins; biotransformation; detoxification; flavin adenine dinucleotide; fumonisins; monoamine oxidase.