Plasmid-encoded mercury resistance in aPseudomonas stutzeristrain that degradeso-xylene

A Pseudomonas stutzeri strain, previously isolated for its ability to utilize o-xylene, bears a plasmid, pPB, of about 80 kbp. pPB was found to encode resistance to mercuric chloride and organomercury compounds. Loss of the plasmid resulted in a simultaneous loss of the metal resistance, but not of the ability to degrade o-xylene. Transfer of the Hgr phenotype to an Hgs strain was achieved by mobilizing pPB with RP4. Mercury reductase activity was induced by mercuric chloride and by phenylmercuric acetate and Thimerosal. pPB may be considered a broad spectrum resistance plasmid.