Pipetting, contamination....

jg374 from cam.ac.uk via methods%40net.bio.net (by jg374 from hermes.cam.ac.uk)
Fri Feb 23 04:54:46 EST 2007

On Fri, 23 Feb 2007, DK wrote:
> In article <1172181256.088647.198980 from a75g2000cwd.googlegroups.com>, "peter" <peter.ianakiev from gmail.com> wrote:
>>> Jeez, I've done this experiment yesterday:
>>> 1. Took a 1 ml Pipetman, set it to 1 ml and pipetted overnight E.coli
>>> culture up and down 20 times.
>>> 2. Immediately after that, changed a tip, took a bottle of sterile
>>> Terrific Broth, pipetted 20 times, set at 37C for 20 hours.
>>> The result: no signs of bacterial growth today ==> no aerosol
>>> contamination.
>>> DK
>> Seems like a good experiment, I just wonder what volume of the TB
>> media you used?
> The standard square bottle filled with 100 ml. I still have that bottle,
> so if you have your doubts, I can look at it very attentively by Monday.
> But, you know, E.coli can grow anaerobically so shaking is not
> strictly necessary...
> I pretty much knew the outcome based on the fact that I am still
> using the same ~1.5 years old bottle of SOC used for an umpteen
> (more like ~ 100 :-)) electroporations, each involving the same
> 1 ml Pipetman and no filter tips all along. Amazingly, still no visible
> growth in the bottle and, as recently as two days ago, 20 out of 20
> clones analyzed contained the expected plasmid.

I coughed into a bottle of SOC a few months ago as an experiment and it 
still looks fresh, however I have seen horrible things growing in SOC 
bottles that have supposedly only been opened under careful flaming.

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