Agar drying in petri dishes, why?

Peter Herman rpeter at
Sat Oct 25 19:37:18 EST 1997

Alan S. Wicks wrote:
> Greetings,
> I transferred some Coprinus comatus to MEA in petri dishes the other day
> (Wednesday).  I wrapped the dished with Parafilm and set them on the
> bench in my lab.  I looked at them this morning, Friday, and they are
> growing but the agar is cracking, even with the Parafilm seal.  The
> other dishes of MEA that I didn't use are still in the transfer hood,
> with the air on, are unsealed, and are NOT cracking.
> Any ideas why or is this normal?

I don't know about Coprinus specifically, but many fungi pull a lot of
water from the agar when they grow.  In many cases you see cracking agar
and condensate on the tops of the petri dishes.
*   Peter Herman, Dept. of Biology      Phone: +1 505 646 4532    *
*   New Mexico State University         Fax:   +1 505 646 5665    *
*   Box 30001, Dept. 3AF                                          *
*   Las Cruces, NM 88003 USA            e-mail rpeter at    *

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