Conjugation of deoxynivalenol by Alternaria alternata (54028 NRRL), Rhizopus microsporus var. rhizopodiformis (54029 NRRL) and Aspergillus oryzae (5509 NRRL)

Abstract

Deoxynivalenol (DON, vomitoxin) is a trichothecene mycotoxin which can be considered to be an indicator of Fusarium mycotoxin contamination in grain, feed and food. Recent studies have described the presence of glucose conjugated DON, which is a product of plant metabolism, but there is a lack of information available on DON conjugation by fungi. The aim of the current study was, therefore, to investigate the ability of fungi to metabolize DON into hydrolysable conjugated DON. Alternaria alternata (54028 NRRL) and Rhizopus microsporus var. rhizopodiformis (54029 NRRL) were found to be capable of metabolizing DON into hydrolysable conjugated DON. This ranged from 13-23% conjugation of DON in potato dextrose agar media and from 11-36% in corn-based media. There was, however, considerable variation between fungal strains in the ability to conjugate DON as only a slight increase in hydrolysable conjugated DON (1-6%) was observed when incubating with A. oryzae (5509 NRRL). A. oryzae (5509 NRRL) was also shown to degrade DON (up to 92%) over 21days of incubation on corn-based media. The current study shows that conjugation of DON can be achieved through fungal metabolism in addition to being a product of plant metabolism.