Date: Sun, 13 Apr 1997 23:52:09 GMT From: Peter Cole <carnivor@flytrap.demon.co.uk> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg1415$foo@default> Subject: Re: TC, Microwaves and Pings
SCHLAUER@chemie.uni-wuerzburg.de writes:
> Sorry, Peter but I have to disagree,
>
> > So long as the medium is heated to between 100'C and 121'C for 2-4
> > minutes it will be effectively sterilised
>
> How do you want to do that with liquid water at normal pressure
> (which can by definition only be heated to 100 degC: any hotter thing
If it was just water I would agree, but it's actually quite a sweet
sugar solution with 30 g/L sucrose (as well as the other nutrients,)
so it boils at rather more than 100'C. I know - I've scalded myself
with water, and I've scalded myself with medium, and the medium's a
lot worse (how's that for scientific method :). I expect the agar
also raises the boiling point though I've not made any detailed
measurements.
121'C is not the limit for sterilisation of course - more would work
fine, but this is the point at which the medium starts to degrade
rapidly which is best avoided.
> is vapour)? OK if solvents are in the water the boiling point rises
> but I have never seen TC media boiling at something even remotely
> similar to 120 degC at normal pressure, and 120 degC is what the
> spores need. So if your procedure works for you that is fine but in
> this case you have not yet experienced the really tricky fungi
That may well be, but in practice it works (virtually) every time.
The kitchen is pretty clean and I close the windows before filling
the flasks, so there's not much chance of anything exotic blowing
in on the wind :)
I'm sure in all the world there are a few micro-organisms that might
survive more heat than most, but if experience is to be counted on
they seem to be pretty rare. The very few contaminations during
filling are, I'm sure, due to my own clumsiness recapping the flasks
rather than spores lurking in the medium.
> (interested in some spores for a test?).
I'll pass on that, thanks anyway :)
Happy growing,
Peter
__________________________________________________________________________
Peter Cole,Cambrian Carnivores,::Carnivorous Plants and seeds for sale -
17,Wimmerfield Crescent,Killay,::http://www.flytrap.demon.co.uk/cchome.htm
SWANSEA SA2 7BU, WALES, UK ::mailto:carnivor@flytrap.demon.co.uk
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