Microwaves: how effective at sterilization

rover at livnet.com rover at ns1.livnet.com
Tue Oct 24 21:11:08 EST 1995

RM Brownlie <rmb10 at york.ac.uk> wrote:

>Recently when in a rush for LB plates I have resorted to 
>microwaving 100 ml quantities and have found these to be clean every time. 
>Does any one know if this is a very reliable method for sterilization. 
>Does it inactivate spores and is sterilization dependant on an aqueous 
>environment? Could it be used to sterilize plasticware for instance.

>Thanks for any response


We routinely use the microwave to heat our LB and LB agar and have
never had any problems. We generally do start with autoclaved LB media
and use the microwave to melt agar when plates are needed, however we
also use the microwave to perform a post use, quick sterilization, by
microwaving opened bottles of LB for two minutes before replacing on
the shelf to await the next use. Since we have placed this routine
into practice about 5 years ago, I have never seen one of our bacteria
media bottles becoming opaque on a shelf..grin

	I dont think that the microwaves generated from an oven are enough,
however, to completely sterilize. Rather the heat from the action of
the microwaves on the moisture is what performs a sterilization...due
to the augmentation of the temperature of the solution, destroying
most sources of comtamination. Therefore, it would probably be
inefficient for plasticware or glass.

	If your looking for a way to sterilize plastic which is not stable at
higher temperatures..ie creates modern art in an autoclave...I suggest
you try gas sterilization if available. If thats not possible, try UV
irradiating. We   routinely sterlize some of our more expensive
plastic plates (the nunc 22x22cm)  by sticking them in a cell culture
hood under UV overnight.

		hope this helps.

--Rover The Mad Molecular Biologist
rover at livnet.com
barlow at picard.evms.edu

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