I have done multiple cultures of E. coli bacteria and related species over the course of my education. Almost every time, they had this revolting smell. However, other organisms used for genetics experiments (eg. Saccharomyces cerevisiae) rarely have a bad scent, if a scent whatsoever. My question is, what is it about the coliform metabolism that produces such a pungent and revolting odor? Any and all answers are appreciated.

  • 2
    $\begingroup$ I'll note that "revolting" is a characteristic of the owner of the nose, not the producer of the scent chemicals; perhaps the nose owning organism evolved an aversion to those chemicals for some reason. $\endgroup$
    – mgkrebbs
    Apr 1, 2020 at 17:48
  • $\begingroup$ xD Well I guess it is, isn't it? $\endgroup$ Apr 1, 2020 at 19:54

1 Answer 1


E. coli and other bacteria metabolize tryptophan into odoriferous skatole and other indole compounds.

If you're culturing these organisms in medium that contains tryptophan, that may be what you're smelling.

  • $\begingroup$ Ah, Skatole! That makes sense. Thank you for your answer! $\endgroup$ Apr 1, 2020 at 19:55

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