Bacterial identification & colony counting from a mixture of 5 different bacteria

JEDilworth bactitech at nospamhortonsbay.com
Thu Sep 12 10:16:37 EST 2002

I come from purely a clinical perspective, with really no experience
with any other type of microbiology. I didn't realize that this stuff
would grow without blood enrichment. I was purely going by the fact
that, even with blood agar, these organisms don't grow very fast.

You're right about blood agar - that's why we use it to grow human

Thanks for the information. I think I'll stick to clinical questions
from now on :-).

Judy Dilworth, M.T. (ASCP)

Lesley Robertson wrote:

> I don't know about the last 2, but the other 3 will grow without blood.
> Indeed, Lactobacilli like tomato juice! I don't encourage beginners to use
> blood plates - you never know what'll turn up and our biosafety laws are now
> incredibly strict!
> Colony counting is not a good way to compare growth rates - not all bacteria
> give 100% recovery on agar, and the results will take several days (at
> least) to collect. You'd be better measuring optical density.
> Lesley Robertson
> http://www.beijerinck.bt.tudelft.nl

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