Help - genomic libary

[Dirk Konz]

Hi there,

I have some trouble with the construction of a genomic libary in the lambda 
Embl 3 vector especailly with packaging efficiency.
After partial digestion of the genomic DNA with Sau3A I factionated DNA of 
15-20 kb via a agarose gel and electroelution. I ligated this DNA with 
predigested vector arms (no PEG in the ligation buffer !) and anlysed the 
ligation mixture by pulsed field gel electrophoresis. The gel showed me that 
the ligation worked well. But the packaging of this DNA yields in very low 
titers. 
If anybody has an idea how to solve this problem, please send me a message.

Advanced thanks for your response.