As we all know, humans have this tendency to consider themselves as the center of the universe. Some of them, with more imagination, think that they are direct creations of a Omnipotent Entity. Well, I’m delighted to consider myself a simple very ape-like human. Where am I trying to get at? well, a subtler way of anthropocentrism is that of roughly classifying bacteria as pathogens and non-pathogens…of humans of course!

A good example of this anthropocentrism is the bacterium I work with: Vibrio cholerae. You wouldn’t doubt for a second to consider this species as a pathogen. OK, what if I told you that more than 99% of the strains of V. cholerae isolated in an endemic area lacked the genes that allow the bacterium to cause the disease?. You would start thinking that it is not particularly advantageous for the bacterium to carry these genes in that particular environment.

We have published a paper this month in nature reviews about the niche specialization of the Vibrionaceae and how we can infer this from the genome sequences.

In the article we brought this issue a little bit further, trying to find possible environmental uses of the “pathogenic” traits of this V. cholerae isolates.

The main cause of the diarrhoea is what we humbly call the Cholera Toxin (CT). CT basically takes salts out from the intestinal cells, a massive efflux of water follows, due to osmotic inbalance and cholera ensued. This “Toxin” can fit better as an osmorregulator in its natural environment, taking salts out of the crustaceans where VC is ubiquitously found. The second main pathogenicity factor is the Toxin Corregulated Pilus (TCP) which allows the bacterium to attach to epithelial cells… and to other things too… for instance, it’s been found that chitin (exoskeleton of crustaceans) induces TCP production, thus allowing the bacterium to bind to it. So we infer that V. cholerae might stablish a symbiotic relationship with copepods (the crustacean) getting a nice niche with food and providing a powerful osmorregulator.

I think this makes more sense than to cause diarrhoea in humans and get washed out in only one day. So “unfortunately” for our egos they are not here only for us baby.