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.