A dirty pipe, a "vet" and wild claims about C. botulinum

By Guest Work 16/08/2013 3

by Dr Heather Hendrickson, Lecturer, Molecular Biosciences, Institute of Natural and Mathematical Sciences, Massey University

When anthrax spores (Bacillus anthracis) were sent in the mail in the US, the response was media hype and mass hysteria.  In the aftermath, there were calls for routine detection and some of these have been put into place.

Dr. Heather Hendrickson
Dr. Heather Hendrickson

In fact, the Anthrax bacterium is found everywhere in very low numbers. This is also true of Clostridium botulinum, the spores of which were recently found in whey by Fonterra.

Frank Rowson, a New Zealand veterinarian, [Ed: After media reports referring to him as a veterinarian, the Veterinary Association issued a statement saying Rowson is not a registered veterinarian and also not a member of the NZVA]  has recently claimed that he believes that the source of the recent Fonterra C. botulinum spores was not a pipe in Hautapu but comes from changes in the microbial content of bovine guts due to feed exposed to the active ingredient in the herbicide RoundupTM, glyphosate. The idea is that the good microbes in the gut are killed by glyphosate and that the bad microbes are then able to replicate and enter the food supply. Rowson refers to research recently published in this area. Indeed, a recent paper published in Anaerobe appears to be his smoking gun.

The paper in question competes large populations of C. botulinum (bad microbes) against large populations of a number of Enterococcal species (good microbes) isolated from animals or algae. The Enterococcal strains inhibit the Clostridium, probably through the production of bacteriocins, small toxins that bacteria produce to kill competitors. All of the bacteria (good and bad) in the study were sensitive to the glyphosphate but the Enterococcal strains were more sensitive and died at lower concentrations of the herbicide.

My assessment is that while the paper is interesting, these data seem to have little to do with the recent Fonterra case. While the use of glyphosphate in agriculture here has quadrupled since the 1960s, I have not found any indications in the literature that C. botulinum infection in cattle is on the rise in NZ, as has been noted in Germany. This suggests that bovine guts are not a breeding ground for this ubiquitous pathogen in New Zealand.

More critically, the paper Rowson cites uses pairs of bacteria growing in test tubes to mimic the gut. The gut is however a surpassingly complex environment. There are easily more than 100 trillion bacteria in a bovine gut (this is the number in our own). That is over 14,000 times the number of people on the planet today. None of the specific bacterial species competed head to head in the Anaerobe paper are major community members in the universe of microbes that is a single cow. If C. boutlinum were so numerous the cattle would be ill and the good microbes tested are always found in an examination of 20 cows but come in as the 10th out of 16 genera.

Put another way, Rowson’s statements are a little like looking at the relationship between a few minority species here on earth and making cataclysmic predictions based on those observations. Say for example that you go to Spain and observe that Yorkie Terriers there are really good at killing rats, but they go home when it rains. If it rains a little in Spain will the planet be over run by rats? No.

This paper may raise concerns about herbicide use but it is a long way from supporting claims concerning the source of spores of a ubiquitous organism found at a Fonterra plant.

Rowson is concerned about the paired use of herbicides and genetic modification in agriculture, an opinion that resonates with many. Pouring herbicidal chemicals into the environment is no one’s ideal approach to farming. That said, the issue of genetically engineered feed that is resistant to RoundupTM should be clearly separated from reasonable discussions regarding the genetic modification of food. With appropriate science, genetically modified foods can be safe, healthful and possibly spare us from the need for mass quantities of herbicides like RoundupTM .

Rowson’s claims of certainty with respect to the source of spores found at Fonterra are unfounded. This organism is found everywhere. If there are increasing populations, then that is worth investigating but short of new data his recent statements appear wildly speculative.


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