restriction cutting Chlamy DNA

[ZEYL,CLIFFORD WESLEY,MR]

  Dear Chlamy net,
In the course of screening      many Chlamy strains, both
 lab lines and new ones we're getting from local soil samples, we've
 run into occasional problems cutting their genomic DNA with standard
restriction enzymes, and are wondering if this ever happens to anyone
else.  Certain run-of-the-mill enzymes (EcoRI, SalI) are particularly
problematic, and certain strains reproducibly don't seem to cut.  We
routinely use the same batches of enzyme to cut plasmids and yeast
genomic DNA with no problems, and the same DNA samples are readily cut
by other enzymes, such as BamHI.  Repeated phenol-chloroform extractions
have no effect.  Does anyone else have these problems, or an
explanation?
                Cliff Zeyl
                b7jm at musicb.mcgill.ca