I need help

Bryan dbd2 at psu.edu
Wed Mar 15 22:47:01 EST 2000



Riffi wrote:

> To answer your questions, I'm in 9th grade Biology. This is sort of an
> optional extra credit assignment. Although the teacher is will help some
> what by setting it up in the lab, we have to get all research ourself, and
> do all the work ourself. The textbook does not cover this area, and the
> school library was not very helpful. And yes, my education is the american
> type (pennsylvania actually).
> Thanks for the help
> Riffi
> Errol wrote:

Dear Riffi:

Regarding pathogenicity; this is the organisms propensity to cause disease.
If you were to leave an agar  plate exposed for say 10 to 15 minutes, airborne
microorganisms including bacteria and fungi might "land" on the surface of a
solid media plate (of the type others are mentioning, usually a 3 inch
diameter plastic dish with jello-like agar media containing goodies for the
bacteria and fungi  to grow upon).  Each dot or "colony" on the surface of the
media is assumed to have arisen from a single organism, fast growing ones will
quickly utilize the surface available on the plate and even inhibit the growth
of others, thus as time goes on, expect a few dominant microbes to take over
the plate.  Even with a microscope, it can be difficult to ID beyond bacteria
and fungi; two major groups of organisms within shich there are multitudes of
different species (this by relative size or even the way they grow on the
plate).  Keep in mind that by the time you see colonies on the plate, each
colony contains probably millions of individual cells, and while one airborne
"bug" is unlikely to cause you any grief, now you've got millions and touching
a colony is not advised.

If you are in central PA (State College/Altoona area) I might be able to help
you and your instructor if you are limited with supplies and know-how.  I am
located at Penn State and can be reached via email:dbd2 at psu.edu if you have
further questions.

Good luck and take care

-Bryan








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