Abstract
A polyphasic taxonomic approach including analysis of phenotypic, physiological and genotypic characteristics, 16S rRNA gene sequence and DNA–DNA hybridization analysis was used to determine the most consistent affiliation of Pseudomonas pictorum. Pseudomonas pictorum ATCC 23328T exhibited phenotypic traits of members of the genus Stenotrophomonas including cellular fatty acid composition, quinone and limited range of substrates that could be used. Antibiotic susceptibility and physiological characteristics were determined. The DNA G+C content was 65.7 mol%. Phylogenetic analysis revealed that the type strains of Stenotrophomonas terrae, Stenotrophomonas humi, Stenotrophomonas nitritireducens and Stenotrophomonas acidaminiphila were the nearest relatives (16S rRNA gene sequence similarity of 98.0 to 98.8 %). All the other type strains of species of the genus Stenotrophomonas showed high 16S rRNA gene sequence similarities (96.8 to 97.2 %). DNA–DNA hybridizations revealed 31.0, 32.0, 43.3 and 43.6% reassociation between Pseudomonas pictorum ATCC 23328T and the type strains of S. terrae, S. humi, S. nitritireducens and S. acidaminiphila, respectively. Our overall results indicate that Pseudomonas pictorum should be transferred to the genus Stenotrophomonas as a novel species of this genus, Stenotrophomonas pictorum comb. nov. Since the original description of the genus Stenotrophomonas was made with only one species (Stenotrophomonas maltophilia), an emendation of the genus description is proposed in order to match better with the characteristics of the eleven novel species assigned to this genus since then.

polyphasic taxonomy; reclassification; cellular fatty acids; 16S rRNA sequences; DNA–DNA hybridization; Stenotrophomonas pictorum comb. nov.