ENVIRONMENTAL GASOLINE-UTILIZING ISOLATES AND CLINICAL ISOLATES OF PSEUDOMONAS-AERUGINOSA ARE TAXONOMICALLY INDISTINGUISHABLE BY CHEMOTAXONOMIC AND MOLECULAR TECHNIQUES

A total of 42 Pseudomonas aeruginosa strains was isolated previously f rom clinical sources (27 strains) and from a gasoline-contaminated aqu ifer (15 strains). Selected strains were subjected to taxonomic tests involving chemical and molecular biological techniques, including memb rane fatty acid analysis, phage-sensitivity, growth temperature range, presence of plasmids, and PCR-amplification and sequencing of a speci es-specific 16S-23S rDNA internal transcribed spacer region, The clini cal and environmental isolates formed a coherent taxonomic group with few distinguishing characteristics. Of the phenotypes observed, a cons istent difference was the ability of the aquifer strains to utilize ga soline supplied in the gas phase as sole carbon source and, conversely , the inability of the clinical strains to do so. Fourteen of the 15 e nvironmental strains possessed similar-sized cryptic plasmids. The cli nical isolates either lacked detectable plasmids or contained plasmids of a different size. The observation that the clinical and environmen tal isolates of P. aeruginosa were taxonomically indistinguishable is discussed in terms of its relevance to environmental-regulatory guidel ines because P. aeroginosa, a known opportunistic pathogen, is a prime candidate for use in bioremediation processes involving deliberate re lease of this organism to the environment.