Summary: Microwave in tissue culture media

Victor M. Jimenez VJIMENEZ%UCRVM2 at UGA.CC.UGA.EDU
Tue Jul 27 19:02:17 EST 1993


Hello,

A couple of weeks ago I asked a question related to the "Effects of microwaving
in tissue culture media".
Unfortunatly I received just a couple of answers.  But anyway, here they are.

Rob Preston <rapr at med.pitt.edu> wrote:

The only possibility that comes to my mind is that it might be possible that the
 solutions just do not have
a significant load of heat-stable bacterial spores present, so simple heating to
 close to boiling suffices for
total sterilization.  The main reason for autoclaving, as far as I know, is to d
eal with heat-stable
bacterial endospores (Bacillus sp., Clostridium sp.)...everything else
likely to be found in media components is killed by near-boiling temps.
Even "heat-stable" spores do die, at some rate, at near-boiling temp, and
if they can be made to germinate, they die much faster.  Possibly microwaves
stimulate bacterial spore germination somehow?  If the number of spores in the
input is low, then the high temp alone would reduce the number of viable
spores below one per total volume heated...since sometimes the method
doesn't work, (i.e., when the input number of spores is too high) you can
see the need for autoclaving in critical applications.  A very old method
for sterilization (I think it might have been called "tyndallization")
involved sequential exposures to alternating regimes of boiling and relatively
low temperatures...this induced spores to germinate at the low temps, and
then the germinated spores would be killed during the next high temp cycle.

Rod Bonfiglioli <rbonfigl at waite.adelaide.edu.au>:

First reference I've seen to microwave work for a while.  There is a dutch
university (Leiden I think) that uses microwaves effectively for all sorts of
things, including tissue fixation and staining.  I feel sure that if you read
some of there stuff you would get a better handle on the question you are
asking.  They did a lot of histo work with microwave, generally less damage
to sections , and about 2-500 times faster.  they used it to accelerate a lot of
other procedures as well, such as restriction digests and other daily molecular
work.

Thank you,

Victor

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  Victor M. Jimenez            vjimenez at ucrvm2.ucr.ac.cr
       CIGRAS                  Tel. (506)-24-8554
Universidad de Costa Rica      Fax. (506)-53-3762
 San Jose, Costa Rica
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