Metabolic fate of ochratoxin A as a coffee contaminant in a dynamic simulator of the human colon

Ochratoxin A (OTA) is a mycotoxin frequently encountered in coffee. The relevance of this contaminant in the colon upon digestion necessitates a study on its interaction with colon microbiota. Here, the fate of OTA during colon digestion was investigated using a dynamic simulator of the human gut. The influence of coffee as a food matrix was taken into account, as it may affect the colonic microbial ecosystem and, consequently, the fate of OTA. Biodegradation was followed by measuring OTA concentration over time, and by screening for several possible metabolites, using LC-ESI-MS and HRMS. The descending colon was found to be the main site of OTA biodegradation. Two metabolites, ochratoxin α and ochratoxin B, were identified, suggesting that biodegradation by gut microbiota is beneficial for the host, as they are considered less toxic than OTA. The extent of biodegradation was reduced in the presence of the coffee matrix, possibly due to competition for available carbon sources. Effects of OTA and the coffee matrix on the microbial ecosystem were contrasting. While OTA caused a specific, but lasting loss, of the beneficial species Lactobacillus reuteri, coffee temporarily altered the fermentation pattern towards lower ammonia and higher acetate and propionate production, likely due to its dietary fibre content.