A nonconjugative mobilizable broad host range plasmid of Acinetobacter sp. that determines HgCl2 resistance

HgCl2-resistant strains of Acinetobacter sp. obtained from the soil at the Khaidarkan mercury mine (Kirghiz SSR) were found to contain, apart from large plasmids (∼60 kb), a small plasmid (∼7.5 kb) designated pKL1. It was established by conjugative crosses and transformation that pKL1 is a broad host range mobilizable plasmid and that it carries the Hgr determinant. The restriction map of pKL1 was constructed; the site of the Hgr determinant and the regions essential to replication were localized. A comparison of these results with earlier data suggests that microorganisms belonging to one microbiocenosis may carry Hgr determinants on plasmids with highly different structures and properties.