In vitro transformation of the Fusarium mycotoxins deoxynivalenol and zearalenone by the normal gut microflora of pigs

Abstract

The biotransformation of the Fusarium mycotoxins deoxynivalenol and zearalenone by the normal bacterial gut flora of pigs was examined in this in vitro study. For that purpose, suspensions of intestinal contents (duodenum, jejunum, caecum, colon, rectum) of porcine origin were incubated anaerobically with deoxynivalenol (DON) or zearalenone (ZEA). DON and ZEA were degraded by the flora of the caudal segments (caecum, colon, rectum) of the gut--particularly the colon content--whereas the microorganisms of the cranial segments (duodenum, jejunum) exhibited no transforming activity. DON was showed to be deepoxidated, ZEA was hydrolyzed to alpha-zearalenol and an unknown metabolite. The transformation of DON was correlated with a loss of cytotoxicity, which could be demonstrated in the MTT(3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium++ + bromide)-cell-culture assay using swine kidney cells as target cells. The results of the study presented here correspond with the data found in in vivo studies. On the basis of these findings one could conclude that this in vitro method seems to be well suited to the study of the transformation of mycotoxins by the microflora of the gut. The in vitro study is cheaper than a feeding trial, and the preliminary information on the metabolism of mycotoxins obtained in such studies is helpful in designing feeding trials more clearly. Besides the simple and fast handling, reproducibility and the protection of the animals studied are further advantages of this in vitro method. In connection with the MTT-cell-culture assay, additional information about the cytotoxic potential of the bacterial transformation products can be obtained.

Binding Rather Than Metabolism May Explain the Interaction of Two Food-Grade Lactobacillus Strains with Zearalenone and Its Derivative ɑ́-Zearalenol

“…In some other studies, transformation of ZEN by microorganisms to more-potent estrogenic zearalenols has been observed (1,7,14,16). This indicates that biodegradation of ZEN by bacteria is not a suitable approach to detoxify ZEN and its derivatives.…”

“…ZEN was reduced stereoselectively by cultures of Candida tropicalis, Zygosaccharomyces rouxii, and seven Saccharomyces strains to both ␣-ZOL and ␤-ZOL (1). When ZEN was incubated with rumen and pig microflora in vitro, it was also reduced to ␣-ZOL and ␤-ZOL (14,16).…”

Biological detoxification of fungal toxins and its use in plant breeding, feed and food production

“…In addition to cows and rats, transformation of DON and other trichothecenes by digestive tract microflora was demonstrated in chickens (He et al, 1992), pigs (Kollarczik et al, 1994), and the ruminal fluid of sheep (Westlake et al, 1989). Other experiments with gastrointestinal microflora failed to demonstrate the deepoxidation of trichothecene in the faeces of chickens, horses and dogs (Swanson et al, 1988) and in the rumen fluid from sheep and cattle (Kiessling et al, 1984;Munger et al, 1987).…”

Fusarium mycotoxins: a review of global implications for animal health, welfare and productivity

“…A recent investigation attempted to elucidate the site at which this activity was greatest in pigs and the nature and relative toxicity of the metabolites formed (Kollarczik et al, 1994). Using an in vitro system it was determined that, as might be expected, microbial transformation of DON was highest in the caecum, colon and rectum.…”

“…The only metabolite detected was de-epoxy-DON, a product also formed in the hind gut of other animals including cattle. Furthermore, it was shown that this transformation of DON was accompanied by a significant loss of cytotoxicity to pig kidney cells (Kollarczik et al, 1994).…”