Autoclaving DNA and contamination

Roger Wiegand rcwieg at
Tue Jun 21 16:50:13 EST 1994

In article <9406211635.4e066e20.LN1 at>,
SCRIMSHAWB%GRIEHFS at LINCOLN.CRI.NZ ("Scrimshaw, Brian J") wrote:

> Has anyone done any experiments, or know of any publications,
> about what autoclaving does to DNA? I remember being told that
> autoclaving shears DNA, but not below 150bp, I have never seen a
> reference on this though.
> Since many PCR products are around this size, this would mean
> autoclaving would not eliminate any small contaminating
> fragments.
> Can someone give me some advice on this?
> Brian Scrimshaw
> Wellington
> New Zealand

Autoclaving should do little or nothing to help reduce PCR contamination.
If I remember correctly from experiments I did *many* years ago, I measured
the rate of breaks introduced into lambda DNA by boiling at about one
nick/molecule/10 min. An autoclave will be at most about 40 deg hotter, so
if the rate doubles for each 20 deg that is still only one nick/50kB/2.5
min. The rate almost surely declines rapidly as the DNA gets shorter,
though I didn't measure that.

I think you'd have to wait geologic times to get down to 150bp.

Sorry, I don't know of a publication on this--just one of those things you
do when you're a graduate student to pass the hours.


rcwieg at
"If you push it hard enough, it *will* fall over"

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