DNA from the cellulase-positive clones
was isolated (16), and enzyme digestion of recombinant
phage DNA from CMC+, OBR-HEC+, and MUC+ clones
was carried out with the restriction endonucleases EcoRI,
SalI, and XbaI. The conditions used were those specified by
the supplier of each enzyme. DNA fragments were fractionated
by electrophoresis in Tris-borate buffer with 0.6% (wt/
vol) agarose gels, and the sizes were estimated by reference
to the migration of DNA molecular weight markers
(XHindIII digest and 1-kb ladder; Bethesda Research Laboratories,
Inc., Gaithersburg, Md.).