Pseudomonas sp. MT14, a Soil Isolate which Contains Two Large Catabolic Plasmids, One a TOL Plasmid and One Coding for Phenylacetate Catabolism and Mercury Resistance

SUMMARY: Pseudomonas sp. MT14, isolated from soil as a result of its ability to utilise m-toluate as sole source of carbon, contains two large catabolic plasmids. One of these, pWW14, is a TOL plasmid of about 270 kb which determines the ability to grow on toluene, m-xylene and p-xylene as sole carbon sources. The other, pWW17, which is about 280 kb, determines both the ability to grow on phenylacetate and resistance to mercury salts. Growth of MT14 on benzoate results in the segregation of derivatives in which either (i) one or both plasmids are completely lost, or (ii) one or both plasmids have undergone a large deletion which results in a change in the phenotype determined by that plasmid. Deletion of about 100 kb from pWW14 results in a regulatory mutation which allows its host to grow on m-xylene but not on its metabolite m-toluate (B3 mutants). Deletion of about 95 kb from pWW17 results in loss of the ability of its host to grow on phenylacetate but the mercury resistance is not lost.