The Human Fecal Microbiota Metabolizes Deoxynivalenol and Deoxynivalenol-3-Glucoside and May Be Responsible for Urinary Deepoxy-Deoxynivalenol

Abstract

Deoxynivalenol (DON) is a potent mycotoxin produced by Fusarium molds and affects intestinal nutrient absorption and barrier function in experimental and farm animals. Free DON and the plant metabolite DON-3-␤-D-glucoside (D3G) are frequently found in wheat and maize. D3G is stable in the upper human gut, but some human intestinal bacteria release DON from D3G in vitro. Furthermore, some bacteria derived from animal digestive systems degrade DON to a less toxic metabolite, deepoxy-deoxynivalenol (DOM-1). The metabolism of D3G and DON by the human microbiota has not been fully assessed. We therefore conducted in vitro batch culture experiments assessing the activity of the human fecal microbiota to release DON from D3G. We also studied detoxification of DON to DOM-1 by the microbiota and its potential effect on urinary DON excretion in humans. Fecal slurry from five volunteers was spiked with DON or D3G and incubated anaerobically (from 1 h to 7 days), and mycotoxins were extracted into acetonitrile. Mycotoxins were detected in fecal extracts and urine by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The fecal microbiota released DON from D3G very efficiently, with hydrolysis peaking after 4 to 6 h. The fecal microbiota from one volunteer transformed DON to DOM-1. Urine from the same volunteer also contained DOM-1 (4.7% of DON), whereas DOM-1 was not detectable in urine from other volunteers. Our results confirm that the fecal microbiota releases DON from its glycosylated form, hence increasing the toxic burden in exposed individuals. Furthermore, this is first evidence that the human fecal microbiota of one volunteer detoxifies DON, resulting in the appearance of DOM-1 in urine. Mycotoxins are common food contaminants in most regions of the world. Deoxynivalenol (DON) is produced by Fusarium molds that frequently contaminate wheat, corn, and barley grown in temperate climates in Europe, South and North America, and some parts of Asia (1, 2). DON is a potent mycotoxin and induces severe intestinal symptoms and feed refusal in farm animals when fed at high concentrations (3). On a molecular level, DON is ribotoxic and hampers protein synthesis in cells. In the intestinal epithelium, DON interferes with the differentiation of enterocytes and disrupts intestinal barrier function (4-7). Advances in mycotoxin analysis have revealed that in addition to the free mycotoxin, cereal samples also contain DON-3-␤-D-glucoside (D3G), which derives from plant phase II metabolism of DON (8). A recent study has found that all cereal samples that were found to be contaminated with DON also contained D3G at levels ranging between 7 and 29% of detected DON in wheat and 5 and 46% of detected DON in maize (9). This suggests that the mycotoxin burden in cereals could be between 14 and 17% higher if these "masked" mycotoxins are taken into account. A recent in vitro study assessed the release of DON from D3G under simulated human intestinal conditions (10). Authors found D3G to be stable under acidic pH and resistant to dig...

Human biomonitoring of multiple mycotoxins in the Belgian population: Results of the BIOMYCO study

“…This incidence is comparable with the 25% found in the pilot survey performed in Belgium (Huybrechts et al, 2014). Our results confirm the suggestion that DOM-1 derives from DON metabolism by intestinal microbiota, whereby not every person possess this activity (Gratz et al, 2013).…”

Modified Fusarium mycotoxins unmasked: From occurrence in cereals to animal and human excretion

“…An interesting observation in the study by Berthiller et al was that the hydrolytic enzyme cellobiase caused a 73% hydrolysis of DON3G after 18 h incubation, indicating that DON could be released in the GI tract of plant-based celluloseforaging ruminants (Berthiller et al, 2011). Gratz et al investigated the metabolism of DON3G by human faecal microbiota and confirmed the above findings (Gratz et al, 2013). After 6 h of anaerobic incubation, 100% of DON3G was hydrolysed in 4 out of 5 cases.…”

Intestinal toxicity of the masked mycotoxin deoxynivalenol-3-β-d-glucoside

“…In vitro data indicated that D3G can be cleaved to DON by lactic acid bacteria and human feces (Berthiller et al 2011;Dall'Erta et al 2013;Gratz et al 2013). These findings correlate well with those of Nagl et al (2012Nagl et al ( , 2014, underlining that the majority of oral administrated D3G was recovered as DON in feces.…”