All true, BUT
To confuse the beginner student:
I think it is Streptococcus mutans that looks like cocci when stained from
agarmedium, and look like definite rods when stained from broth.
(but it is a rare exception, so don't let it bother you).
Loes
Graham Shepherd wrote:
> You will also find that eg streptococci are only seen in chains when you
> grow them in broth and prepare the smear directly from it. Lots of fragile
> morphological features may be altered by growing on solid media and
> subsequent handling.
>> GS
>> Karl Roberts wrote in message ...
> >Hi Mike,
> >I'll venture a guess at this question. In liquid media, bacteria are not
> >as crowded. There is less competition for space and nutrients (at least in
> >young, fresh cultures), so cells are more likely to assume a more natural
> >appearence and arrangement. Our strain of E. coli, for example, takes on
> >a more robust rod-shape when cultured in liquid medium, but when grown on
> >an agar slant or plate tends to appear more as a classic coccobacillus
> >with greater variations in individual appearence. This can also be true
> >for different species of Bacillus, etc. This is my current take on the
> >situation, and I am looking forward to other responses.
> >Karl J. Roberts, Ph.D.
> >PGCC
> >
> >On Fri, 5 Mar 1999, Mike wrote:
> >
> >> Unfortunately I've lost the old note, but someone suggested (to me, a
> >> beginner student) that it was advantageous to use liquid media instead of
> >> solid media when having difficulties differentiating between rods and
> cocci.
> >> Why is this?
> >>
> >>
> >>
> >
