Temperature to pour plates

John Tudor jtudor at sju.edu
Tue Feb 14 13:54:08 EST 1995

It would be best to cool the agar in a waterbath to 45 - 50 C before
pouring.  Another method would be to pour plates without milk, let
them solidify, and then spread a known quantity of milk over the
surface, incubate and observe for growth.
Paul A. Vescio (vescip at rpi.edu) wrote:
: In Article <3hdnig$6rr at post.its.mcw.edu>, ckrepel at post.its.mcw.edu (Candace
: Krepel) wrote:
: >: WmsFan (wmsfan at aol.com) wrote:
: >: : Here's an easy one for you microbiologists. My son is doing a simple
: >: : science experiment looking at the effect of temperature on growth rates of
: >: : bacteria in milk. We got some sterile agar and plates from a local
: >: : company. We melted the agar, added milk to the plates with sterile
: >: : pipettes, and are about to pour the media....but I imagine we could
: >: : sterilize the milk if we pour the agar too hot. What temperature should we
: >: : cool the agar to before we pour it?

: Agar solidifies below 60C. We do a very similar experiment in the Micro lab
: at RPI. If you pour the plates to hot it will curdle the milk when added
: probably affecting alot of the microbes also, although I suspect any
: lactobacillus present are fairly heat resistant.  A good general rule that
: we teach micro students is that if the agar is cool enough to hold against
: your cheek (sensitive skin) comfortably then it is cool enough to add
: bacteria or in this case Milk. 
: Paul A. Vescio
: Biology Dept.
: Rensselaer Polytechnic Institute

: !!New York Rangers  Stanley Cup Champions 1994!!

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