Gene disruption

[herzer at urz.unibas.ch]

I am attempting to disrupt a gene in a strain of E. coli which is not well
characterized (the strain, not the gene).  I have a plasmid construct which
carries my gene with a chloramphenicol resistance gene inserted into it.
So if I get a double crossover of homologous recombination then my strain,
which is Cm-sensitive, should then become Cm-resistant.  I am using a
temperature-sensitive mutant of pGB2 which grows at 30C but is kicked out
at 42C.  The problem is that there are a high amount of revertants with
this plasmid and I have a very high background.  Does anyone know of any
other good plasmids which could be used for this purpose; i.e. temperature
sensitive or "suicide" plasmids,etc.  I would be most greatful for any 
suggestions.

 Thanks,
                        Pete
                        "Herzer at urz.unibas.ch"