Brown E.coli

Trond Erik Vee Aune trondaun at
Sun May 22 04:27:06 EST 2005

JEDilworth wrote:
> Years ago (70's) I recall having an E. coli that was extremely mucoid
> that produced huge zones on a Kirby Bauer plate (for the sensitive
> drugs). It was from a renal patient and was not typical at all. Renal
> patients tend to have very atypical strains of everything because
> they're treated so much.
> I don't remember if it was brown. I have seen Pseudomonas aeruginosa
> that was brownish red, however. Was the organism oxidase positive? I
> would check that if I had it on a patient's culture plate.
> I assume you're doing some sort of further testing/research to elucidate
> a particular strain of EC. Clinical labs don't go that far, and I'm
> sorry if I'm uneducated in that area.

Thanks for your answer. We're quite sure the strain is lin239, and that 
there's been no mutations in it. The wierd thing is that when we grow it 
on solid media with lots of m-toluic acid it produces this brown 
pigments. I didn't know that E.coli was capable of this, I've never 
heard of brown colonies before. So I was wondering if people have seen 
this happen before, and maybe suggest what the metabolism is. I know 
that some other enterococci can produce browin pigments, so it may be a 
homologue pathway, but which one, and what is the purpose of the pigments?

Trond Erik

> Judy Dilworth, M.T. (ASCP)
> Microbiology
> "Trond Erik Vee Aune"
> <trondaun at> wrote in message
> news:d6f81c$rei$1 at
>>A collegue of mine have managed to get brown E.coli lin239 colonies on
>>solid media.

Trond Erik Vee Aune
Department of Biotechnology
Norwegian University of Science and Technology

- Must be sad being a dyslectic, agnostic insomniac, lying
   awake during the night, wondering if there really is a dog

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