PARTIAL CHARACTERIZATION OF SMALL PLASMIDS FROM CORYNEBACTERIUM-RENALE

A naphthalene-degrading strain of corynebacteria, Corynebacterium rena le, harbors multiple small plasmids designated pCR1, pCR2, pCR3, and p CR4 with sizes of 1.4, 3.2, 4.4, and 5.7 kb, respectively. Plasmid pCR 1 of 1.4 kb is the smallest plasmid reported in this group of bacteria and is present in high copy number. Attempts to clone whole pCR1 in E scherichia coli were unsuccessful but two of its fragments (750 and 65 0 bp) could be separately cloned in it. The 4.4-kb plasmid, pCR3, bear s considerable restriction pattern similarity to a 4.4-kb plasmid belo nging to the pBL1 group of cryptic plasmid of corynebacteria but has n o sequence homology, suggesting that pCR3 represents a new member of t he 4.4-kb group of corynebacterial plasmids. (C) 1995 Academic Press, Inc.