**Help** phage screening problem

neale at mbcf.stjude.org neale at mbcf.stjude.org
Fri Sep 8 10:56:37 EST 1995


We have an odd problem at the moment regarding screening phage libraries. We
have two libraries (one made by us, and another obtained from another lab) that
we are trying to screen.

We titered the libraries on our host cells (LE392) just fine. The titers were
what we expected. However, the problem is when we go to the large scale plating
(50,000 per 150 mm dish). We get no lysis at all! This is despite using the
same host cells, agar, etc that were used to titer the library. We have even
re-titered in parallel with the large scale plating using the same dilutions of
phage and get great plaques on the titer plates but no lysis on the larger
plates. 

I've never encountered this before in screening libraries. Both libraries
behave identically. The only difference that I can think of is that the phage
adsorption in the large scale plating is done in a polypropylene tube while the
adsorption of the titering bacteria is done in glass tubes.I've not heard of
phage being inactivated or  adsorbing to plastic, and I've certainly done this
in the past without mishap. In fact, the dilutions of phage are made in epp
tubes.

Any ideas or similar experiences? I'm rather baffled by it all!

Geoff



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