(I've taken the liberty of changing the subject line as the original one
seems to have been a mistake, and likely to cause the message to be trashed
unread by many people)
"Jones' Sock Puppet" asked:
>We are studying a variety of pathogen's growth rates based on
>spectrometery results and I was wondering if the fact that they were
>both gram- and + would affect the results. As well as being
>fermentative would affect it. Our instructer said that the organisms
>being gram - or + OR that some are fermentative or non-fermentative
>effects our growth rate results. The bacteria we are working with are
>Steptococcus faecalis, Staphylococcus epidermis, Proteus mirabilis,
>and Alcaligenes faecalis. I have found that the resuts are very close
>in Strep and Staph which I atribute to the closeness in their
>metabolic pathway but with the question our instructor posed I am at a
>loss as to the other two. I can only assume that there is some
>correlation between her question and the results.
>All these things could affect the growth rate of an organism, and in
general I feel that you are putting the question the wrong way round. It's
not so much a question of why they are not all the same but why one might
ever expect them to be the same in the first place. As long as two
organisms are not competing for exactly the same resources there is no
necessity for the faster growing one to eliminate the slower (though this
may of course happen sometimes). However, there are people more expert in
bacterial growth than I am who follow this news group (Douglas, are you
there?), and with any luck they can give you a much more expert answer.
In the case of Steptococcus and Staphylococcus I'm not too happy with your
reference to "the closeness in their metabolic pathway". I think you
probably mean the similarity of their metabolism, but that is not the same
thing. (A metabolic pathway is normally regarded as just a small part of
metabolism).
I can't of course speak for your instructor, but maybe she didn't envisage
a unique "right answer", but just wanted you to examine and discuss the
various factors that might cause different organisms to grow at different
rates.
athel
--
Athel Cornish-Bowden athel at ibsm.cnrs-mrs.frhttp://ir2lcb.cnrs-mrs.fr/~athel/homepage.htm
Phone: + 33 491 16 41 38; fax: + 33 491 16 45 78
CNRS-BIP, B.P. 71, 13402 Marseille Cedex 20, France
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