Isolation and characterization of a streptomycin resistance plasmid from Pseudomonas cepacia.

A plasmid, Rms425, mediating resistance to streptomycin(Sm) and mercury(Hg) was isolated from Pseudomonas cepacia GN11131 of clinical origin. Rms425 was transferred to Pseudomonas cepacia, Pseudomonas aeruginosa and Escherichia coli strains by transformation with purified DNA and by conjugation between isogenic strains of P. aeruginosa or of E. coli by mixing on membrane filters. The molecular weight of Rms425 was estimated to be about 32 megadaltons by electron microscopy and it was classified as incompatibility group P. Examining the incorporation of [gamma-32P] or [8-14C] from isotope-labelled ATP into Sm using the cell-free extracts from P. cepacia or E. coli strains harboring Rms425, we found that the Sm resistance conferred by Rms425 was due to the phosphorylation of the drug.