New insights into botulism toxin

10th September 2014

SEM of Clostridium botulinum. Image by Kathryn Cross

SEM of Clostridium botulinum. Image by Kathryn Cross

A recent study from the Institute of Food Research has uncovered new information about the genes Clostridium botulinum uses to produce its deadly toxin.

An analysis of closely related strains of one particular type of C. botulinum showed that the toxin genes are carried exclusively on plasmids, and the plasmids were linked to the geographical origin of the strain.

The botulinum toxin is incredibly potent, and minute amounts can cause paralysis and death, so much effort at IFR and around the world goes into understanding how the bacteria grow and produce the toxin, to help ensure it doesn’t get into the food system.

To date, eight different types of botulinum toxin have been identified. In this new study, published in the journal Genome Biology and Evolution, the researchers compared genes from strains producing one particular toxin, isolated from different environments at different times. Surprisingly, they didn’t find the toxin genes on the bacterial chromosome, but instead found them solely on plasmids. They also discovered a common set of genes on the plasmids that they believe make it almost impossible for the bacteria to lose the plasmid, through interaction with related genes within the chromosome.

The researchers also found that the plasmids separated into different types, those from bacteria isolated from marine environments, and those isolated from human botulism cases linked to meat products. This knowledge will be invaluable when trying to trace the origins of new strains of C. botulinum. 

Read more about this study in a blog post by Dr Andy Carter, on the Gut Health and Food Safety blog

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