Plasmid occurrence and diversity in the genus Paracoccus.

The results of screening for the occurrence of plasmids in several strains representing 11 out of 13 species of the genus Paracoccus are presented. We show that plasmids (ranging in size from 2.7 to above 450 kb) are widely distributed in this genus. Only one tested strain (P. alkenifer) appears to be plasmid-free. The majority of the strains harbour at least two plasmids, one of which usually fits into the class of megaplasmids.