Porcine small and large intestinal microbiota rapidly hydrolyze the masked mycotoxin deoxynivalenol-3-glucoside and release deoxynivalenol in spiked batch cultures in vitro

Mycotoxin contamination of cereal grains causes well-recognized toxicities in animals and humans, but the fate of plant-bound masked mycotoxins in the gut is less well understood. Masked mycotoxins have been found to be stable under conditions prevailing in the small intestine, but are rapidly hydrolyzed by fecal microbiota. This study aims to assess the hydrolysis of the masked mycotoxin deoxynivalenol-3-glucoside (DON3Glc) by microbiota of different regions of the porcine intestinal tract.

Intestinal digesta samples were collected from the jejunum, ileum, caecum, colon and feces of 5 pigs and immediately frozen under anaerobic conditions. Sample slurries were prepared in M2 culture medium, spiked with DON3Glc or free DON (2 nmoles/mL) and incubated anaerobically for up to 72 hours. Mycotoxin concentrations were determined using LC-MS/MS and microbiota composition was determined using qPCR methodology.

Jejunal microbiota hydrolyzed DON3Glc very slowly, while samples from the ileum, caecum, colon and feces rapidly and efficiently hydrolyzed DON3Glc. No further metabolism of DON was observed in any sample. Microbial load and microbiota composition was significantly different in the ileum, but similar in caecum, colon and feces.

Importance

Results from this study clearly demonstrate that the masked mycotoxin DON3Glc is hydrolyzed efficiently in the distal small intestine and large intestine of pigs. Once DON is released, toxicity and absorption in the distal intestinal tract are likely to occur in vivo. This study further supports the need to include masked metabolites into mycotoxin risk assessments and regulatory actions for feed and food.