Abstract
Plasmid pUO1 which specifies haloacetate dehalogenase H-l and H-2 and mercuric reductase was isolated from a fluoroacetate-assimilating Moraxella1 strain B. From the spontaneous mutant deficient in H-2 enzyme derived from strain B, plasmid pUOl 1 specifying H-l enzyme and mercuric reductase was also isolated. The molecular sizes of pUOl and pUOll were estimated to be 43.7± 1.6 Mdal and 40.1 + 1.3 Mdal, respectively, by electron microscopy. These values were in good agreement with those estimated by electrophoretic analyses of the cccDNAand its restriction endonuclease digests. The digestion patterns of both plasmid DNAswere analogous, suggesting that plasmid pUOl l was the deletion mutant derived from pUOl. It could be presumed that the deleted DNAsegment had a molecular size of about 3.6 Mdal.
