Why? In vivo exsicion didn't work.

[Mari L. Shinohara]

Hello folks,

I recently had a problem on in vivo excision of DNA insert in lambda
ZAP phage.  I did not get any E. coli colonies then.  Though it has
been solved anyhow fortunately, I'd like to know what was the
problem...

--- I used the XL1-blue strain grown on LB+Tet plate and followed the
protocol supplied by Strategene.  I tried it 5 or 6 times, but no
colonies appeared.  I was desperate and got XL1-blue from my friend,
which was also grown on LB+Tet just I did.  Then...  It worked.  I did
the prep exactly in the same way.  Well...  May be I vortexed tubes
after adding lambda and helper phages together with bacterial cells,
when I was using my E. coli.

Is it possible that my bacterial cells had some problem even though I
had used Tet selection?  Or vortexing made my experiment ruined?

Your help will be greatly appreciated!

Mari