Physiological role of E.coli
arlin at is.dal.ca
Tue May 6 18:53:49 EST 1997
Ivan Yu. Torshin wrote:
> Hello, world !
> While trying to elucidate (by reading) physiological role of several
> periplasmic enzymes from E.coli, a question arose:
> What are physiological functions of human E.coli ? What
> substances does it produce/'eat' ?
E. coli lives in the intestines of most mammals, and is also
found in some other tetrapods, as well as some insects. In
humans, E. coli is an extremely minor component of the
intestinal flora-- most intestinal microbes are anaerobic,
and Bacteroides fragilis, the most common component, is
about 2 or 3 orders of magnitude more dense than E. coli
in colon contents. You could probably find out more by
posting your question to bionet.microbiology.
It may be a mistake to assume that E. coli has a "function"
for humans. E. coli may not benefit mammals at all. How
would mammals prevent it from living there, given that they
are so generous in providing homes for other microbes? And
even if E. coli has a "function" for some mammals, it may
be living in humans just because it can.
That having been said, at least some E. coli strains synthesize
vitamin K (don't ask me what that is, chemically). Whether
one wants to call this a "function" depends on the evolutionary
history of this relationship, and how anthropocentrically one
wishes to define "function".
Department of Biochemistry
Halifax, Nova Scotia B3H 4H7 CANADA
(email) arlin at is.dal.ca
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