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lamb L.A.M.Buisman at chello.nl
Fri Jul 6 15:59:02 EST 2001

Austin Reade wrote:

> Is it possible that commercial agars available today are manufactured to be
> more easily dispersed after direct autoclaving than agars available years
> ago?  In the dim and distant past I seem to remember that it was quite
> difficult to disperse the agar component if you autoclaved it without prior
> mixing and heating.  A lump of agar with a gelatinised outer skin and poorly
> hydrated centre would tend to form in the bottom of the flask.  Once this
> experience is embedded in ones brain it then becomes one of the protocols
> noted by Dr. Evdokimov.

I have never seen anything else then direct autoclaving. I started in '68 ,

> One lab I worked in routinely used a microwave to prepare selective agar
> media which didn't require sterilization.  With some practice one could set
> the time to obtain a boiling solution without boilover.  However the colour
> of the inside of the microwave attested to many failed experiments before
> this happy state was reached.

The problem could be the starting temperature. During heatwaves everything boils
over and in winter the lumps. Or somebody clever used tight screwcaps.


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