Autoclaving DNA and contamination

Duncan Clark Duncan at
Thu Jun 23 07:55:37 EST 1994

In article: <1994Jun22.191935.22141 at>  brianf at (Brian Foley) writes:
> 	Autoclaving is great if the buffer or solution is not 
> contaminated with DNA to begin with.  The autoclaving will sterilize
> the solution, thus preventing bacteria from growing up and synthesizing
> DNA.
> 	I would think that if you are making these large batches of
> buffers for PCR, you are taking care not to use flasks that were previously
> used to harvest DNA.


> 	On the other hand... if I had a solution in my lab that somehow 
> got contaminated with a plasmid, and I needed to cure that solution of 
> such contamination, I would not trust autoclaving to do the job.  UV
> light would probably work better.  But the real solution is to prevent the
> contamination in the first place.

How can one UV irradiate 20 litres of buffer? I suppose I could recirculate it
through some thin UV transparent tubing with UV lamps on either side. How
long does one need to irradiate for, 30 mins?

The other potential problem is the vials themselves. I know a supplier
of 0.2ml PCR tubes has found levels of up to 10x3 bacteria per tube in some
newly made tubes. Obviously one can kill these by autoclaving etc but from what
everyone says the DNA will still be there.   

As I say ther hasn't been a problem but the potential is obviously there. I
wonder how other manufacturers prepare their buffers. Maybe I should put a
few units of DNAse in the buffers prior to autoclaving!!!

Keep the comments coming. All very useful.


Duncan Clark                        | Internet:    duncan at
GeneSys Ltd.                        | Compuserve:  100015.1406 at

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