Pseudomonas libanensis sp nov., a new species isolated from Lebanese spring waters

The taxonomic position of eight fluorescent Pseudomonas isolates, from two Lebanese spring waters, which were previously recognized by numerical analy sis as members of a new subcluster (subcluster Vb) was examined. Except for one strain, the new subcluster exhibited internal DNA hybridization values of 76-100 %, and 9-53 % hybridization was measured with the type or refere nce strains of other Pseudomonas species. The highest DNA binding value was found with Pseudomonas marginalis strains (37-53 %). The G + C content of the DNA of the type strain was 58 mol%. A comparison of 1322 nt of the 16S rRNA gene sequence of the strain representing subcluster Vb (CFML 96-195(T) ) with the sequence of other strains of the genus Pseudomonas revealed that strain CFML 96-195(T) was part of the 'Pseudomonas fluorescens intrageneri c cluster'. On the basis of the results of phenotypic, DNA-DNA and phylogen etic analyses, a new Pseudomonas species, Pseudomonas libanensis sp. nov., is proposed for the seven strains of subcluster Vb. The type strain is P. l ibanensis CFML 96-195(T) and has been deposited in the Collection de l'Inst itut Pasteur (Paris, France) as CIP 105460(T). The P. libanensis strains ar e phenotypically and genotypically homogeneous and can be differentiated fr om most other fluorescent species by several phenotypic features. Different iation of P. libanensis and Pseudomonas aeruginosa is based mainly on pyocy anin production; P. libanensis can be differentiated from P. fluorescens (a ll biovars) by alpha-aminobutyrate assimilation. The clinical significance of P. libanensis is unknown.