I am interested in models showing how pathogenic bacteria (namely Escherichia coli O157) can overcome commensal species (thus, causing a disease). This is a basic concept in biology but I can't find a proper article describing it.

I am looking, essentially, for a co-culture experiment with a pathogenic and a non-pathogenic bacteria that shows how the former can outcompete the latter. Is there a reference to such experiments?


  • $\begingroup$ Are you sure you know what a commensal species is because the Wikipedia definition is incompatible with one member overcoming another: "Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed" ? And which species do you maintain Escherichia coli O157 outcompetes — could you cite references on this point? $\endgroup$
    – David
    Jun 8 '21 at 17:18
  • $\begingroup$ @David, I believe Gigiux is using commensal with respect to the hosting organism (e.g. human), contrasting those species with E. coli O157, which is not commensal with the host. $\endgroup$
    – mgkrebbs
    Jun 8 '21 at 18:38
  • $\begingroup$ @mgkrebbs OK. But does the O157 strain have to complete with the commensal strain? For what? There are dozens of different bacteria in the gut managing to share resources. $\endgroup$
    – David
    Jun 8 '21 at 18:55
  • $\begingroup$ @David, This usage of commensal is pretty consistent with the usage in most gut microbiome literature. Although I agree with you that it is probably used incorrectly most of the time, it seems like a fair enough label to apply until a specific harm or benefit for the host has been empirically demonstrated. $\endgroup$
    – MikeyC
    Jun 8 '21 at 21:06
  • $\begingroup$ @MikeyC OK I misunderstood the OP with regard to commensal, but — and I am asking with skepticism but out of ignorance — does O157 compete with K12 (or whatever) as his question implies? Because this is the crux of the viability of what he proposes. To do competitive growth experiments it would have to be established that the two strains complete for some nutrient, and what that nutrient is to be able to construct a growth medium. If this is true/know one would imagine it is also known what O157 does better — induce some enzyme, or whether its toxin affects K12. I think the OP should clarify. $\endgroup$
    – David
    Jun 8 '21 at 22:31

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