Mycotoxin Contamination in Scottish Cereals and Toxicity Towards Human Gut Microbiota

Mycotoxins are unavoidable food contaminants produced by moulds and present in agricultural crops. Mycotoxin exposure is a major health issue globally. In temperate climates of Europe and North America, Fusarium moulds most commonly infest agricultural crops and produce an array of Fusarium mycotoxins. Amongst them, deoxynivalenol (DON) is the most prevalent mycotoxin in various cereal crops. DON has been shown to have strong toxic effects on the intestinal epithelium of the upper gut, disrupting intestinal barrier function and nutrient absorption (Maresca 2013).

In addition to parent mycotoxins, evidence on the presence of plant metabolites, so called masked mycotoxins, is mounting in the literature. These previously undetectable compounds are present in most contaminated plant material and can mount up to 20% of additional mycotoxin contamination. These compounds are unabsorbed in the upper gut and will be delivered to the colon. We have shown previously that human gut microbiota will quickly and completely degrade masked DON (Gratz et al. 2013) and release free mycotoxins into the colonic environment.

The toxicity of these free mycotoxins towards the intestinal microbiota and the colonic tissue are not known. One published study suggests that oral mycotoxin exposure alters microbiota composition in human microbiota associated rats with an increase in Bacteroides/Prevotella group relative to total bacterial abundance (Saint-Cyr et al. 2013). However, a detailed evaluation of mycotoxin toxicity towards gut bacteria is missing.

Hence the current study aims (a) to investigate the presence of mycotoxin producing fungi, mycotoxins and masked mycotoxins in cereal crops collected at various sites throughout Scotland and (b) to study the toxicity of mycotoxins towards main groups of intestinal bacteria.
Cereal samples will be collected through the established crop monitoring programme at the Scottish Rural University College (SRUC). SRUC carries out cereal field trials across the key arable regions of Scotland, from which samples from a range of hosts, varieties and fungicide regimes could be sampled. They also manage the Scottish Government’s crop health surveillance programme (Advisory Activity 314) known as the ‘adopt-a-crop’ scheme. This would allow samples to be collected from commercial farms throughout the main arable regions to be collected, along with full crop history. Mycotoxins will be extracted and determined using LC-MS/MS technology established at University of Aberdeen.

Mycotoxin toxicity towards gut microbiota will be studied in pure cultures of dominant gut bacteria. Bacteria will be exposed to DON in vitro and toxicity will be assessed in various assays:

1. Functional approach: Study mycotoxin toxicity towards basic bacterial functions including bacterial cell growth, membrane integrity and metabolic activity.

2. Molecular approach: Elucidate potential novel modes of toxicity using transcriptomic analysis.