Could the Fonterra botulism scare be down to herbicide use and GM crops?

According to an article in the Stuff, Matamata veterinarian Frank Rowson says the contamination of Fonterra’s whey powder with the toxin-producing bacterium Clostridium botulinum is linked to contamination of the food chain by glyphosate weed killers. Glyphosate is better known as the Monsanto product Round Up, to which the company developed genetically resistant crops so that farmers could use glyphosate to kill weeds without killing their crops.

Frank Rowson is quoted as saying he has research showing that:

“GM feeds and the use of increased amounts of glyphosate herbicides increases the prevalence of this disease in pigs, poultry and dairy cattle, and the neuro toxin that causes the disease will pass through the food chain into milk.”

Firstly, Fonterra and MPI have made it clear that it was not the toxin but the bacterial spores that contaminated the whey powder. So if we put that aside for the moment, what is the possibility of the spores passing into the food chain through milk?

Rowson seems to be referring to this paper by Krüger et al in the journal Anaerobe earlier this year (h/t to Thomas Lumley) [1]. Alas, the article is not open access so I haven’t been able to read it this evening but according to the abstract the normal intestinal microflora is critical in preventing C. botulinum from colonising the intestine, by producing toxins which inhibit the bacterium. The authors report that glyphosate is toxic to the most prevalent species of Enterococcus in the gastrointestinal tract and suggest that ingestion of herbicide could therefore lead to the colonisation of cattle by C. botulinum.

According to the Irish Department Agriculture, Food and the Marine, the C. botulinum toxin types that cause disease in cattle are C and D, which do not cause disease in humans. Fonterra still haven’t released information on the type of C. botulinum which contaminated their whey powder, but given the recall, we can assume it was either A, B, E or F, the types which cause botulism in humans. From this, it would seem that Rowson’s claim that the source of the Clostridial contamination is linked to glyphosate usage and cattle is highly questionable.

Reference:
1. Krüger M, Shehata AA, Schrödl W, Rodloff A. 2013. Glyphosate suppresses the antagonistic effect of Enterococcus spp. on Clostridium botulinum. Anaerobe. 20:74-8. doi: 10.1016/j.anaerobe.2013.01.005. Epub 2013 Feb 6.

UPDATE 15/8/13:

I’ve now had a chance to read the paper and what the authors have done is look at the growth (in the lab, not in cows) of different types of C. botulinum in the presence of different species of Enterococci. The Enterococci do indeed inhibit the growth of C. botulinum to different degrees (data presented as mean +- standard deviations from n = 3 ). They then went on to look at the effect of incubating type B C. botulinum with E. faecalis, with and without glyphosate added. Weirdly, the results using no glyphosate don’t match the previous data as there doesn’t seem to be any inhibition of the C. botulinum. In fact, all I can tell from their experiments is that E. faecalis is very sensitive to glyphosate (no bugs left after incubation with 0.1 mg/ml) while C. botulinum is less affected although it does go from 10,000,000 bugs/ml with no glyphosate to 1,000 bugs/ml with 10 mg/ml glyphosate.