We propose the name Pseudomonas monteilii for a new species of gram-negative, rod-shaped, motile bacteria that were nonhemolytic on blood agar and were isolated from clinical sources. The 10 strains of P. monteilii were incapable of liquefing gelatin. They grew at 10°C but not at 41"C, produced fluorescent pigments, catalase, and cytochrome oxidase, and possessed the arginine dihydrolase system. They were capable of respiratory but not fermentative metabolism. They did not hydrolyze esculin or starch and were able to use benzylamine, aaminobutyrate, D-ribose, L-arabinose, butyrate, valerate, isovalerate, isobutyrate, inositol, phenylacetate, D-alanine, and amylamine. They possessed L-phenylalanine arylamidase, L-lysine arylamidase, L-alanine arylamidase, y-glutamyl-transferase, glycyl-phenylalanine arylamidase, L-tryptophan arylamidase, glycyl-L-alanine arylamidase, esterase C , , esterase C , , esterase C , , esterase C , , esterase Cl0, and esterase CIS. DNA relatedness studies revealed that P. monteilii strains formed a homogeneous DNA hybridization group. A total of 57 strains representing previously described or partially characterized taxa belonging to the genus Pseudomoms were 6 to 54% related to P. monteilii. The highest hybridization values were obtained with strains belonging to or related to Pseudomonasputida biovar A. The average G+C content of the DNA was 60.5 0.5 mol% for four of the P. monteilii strains studied. The type strain of P. monteilii is CFML 90-60 (= CIP 104883); it was isolated from bronchial aspirate and has a G+C content of 60 mol%. The clinical significance of these organisms is not known.It is generally accepted today that the genus Pseudomonas, as described in Beigey's Manual of Systematic Bacteriology (32), was multigeneric and should not be maintained as a single genus (11-13, 33,34,53,60,61) Pseudomonas aeruginosa , Pseudomonas jfuorescens, Pseudomonas putida, Pseudomonas chlororaphis (5, 23, 39, 51), and the plant-pathogenic Pseudomonas species (Pseudomonas syringae and Pseudomonas cichorii) are the most important fluorescent species (34). Two other species, Pseudomonas veronii (16) and Pseudomonas rhodesiae (6), have been described recently for fluorescent Pseudomonas strains isolated from natural mineral waters (15). A common characteristic of all of the above organisms is the production of pigments that fluoresce under short-wavelength UV light (25). Taxonomically, the fluorescent pseudomonads are extremely complex. The plantpathogenic fluorescent pseudomonads (17, 32) are characterized by a negative arginine dihydrolase reaction and represent a branch that is phylogenetically separate from the other fluorescent organisms in similarity group I of Palleroni (32). P. aeruginosa, the type species of the genus Pseudomonas, is a typical opportunistic pathogen (3). Most strains of this species can be easily identified by a number of phenotypic characteristics (34). This is a homogeneous species on genotypic grounds (35).P. jfuorescens and P. putida were described a few years after...

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The taxonomic position of eight fluorescent Pseudomonas isolates, from two Lebanese spring waters, which were previously recognized by numerical analysis 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 reference 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 96-195T) with the sequence of other strains of the genus Pseudomonas revealed that strain CFML 96-195T was part of the 'Pseudomonas fluorescens intrageneric cluster'. On the basis of the results of phenotypic, DNA-DNA and phylogenetic analyses, a new Pseudomonas species, Pseudomonas libanensis sp. nov., is proposed for the seven strains of subcluster Vb. The type strain is P. libanensis CFML 96-195T and has been deposited in the Collection de l'Institut Pasteur (Paris, France) as CIP 105460T. The P. libanensis strains are phenotypically and genotypically homogeneous and can be differentiated from most other fluorescent species by several phenotypic features. Differentiation of P. libanensis and Pseudomonas aeruginosa is based mainly on pyocyanin production; P. libanensis can be differentiated from P. fluorescens (all biovars) by alpha-aminobutyrate assimilation. The clinical significance of P. libanensis is unknown.

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