Stenotrophomonas lactitubi sp. nov. and Stenotrophomonas indicatrix sp. nov., isolated from surfaces with food contact.

Five Gram-stain-negative, rod-shaped, none-spore-forming isolates were obtained from biofilms on different sites of a milking machine in Germany. Another strain with similar morphological characteristics was isolated from dirty dishes. Based on phylogenetic analysis of the 16S rRNA and gyrB genes, all isolates were assigned to the genus Stenotrophomonas, but were divided into three different groups. Chemotaxonomic characterization of the isolates led to the detection of iso-C15 : 0 and anteiso-C15 : 0 as the predominant cellular fatty acids, as well as small amounts of the hydroxyl fatty acids iso-C11 : 0 3-OH, C12 : 0 3-OH and iso-C13 : 0 3-OH. One group could be assigned to the species Stenotrophomonas maltophilia, while the genome sequences of two groups displayed average nucleotide identity values of less than 94 % between each other and the genome sequences of the next related type strains Stenotrophomonas maltophilia ATCC 13637 and Stenotrophomonas rhizophila DSM 14405. Further phylogenetic, phenotypic and chemotaxonomic analyses enabled the differentiation of these strains from these closely related species. They are therefore considered to represent two novel species, for which the names Stenotrophomonaslactitubi and Stenotrophomonasindicatrix are proposed, with strains M15 (=DSM 104152=LMG29943) and WS40 (=DSM28278=LMG29942) as type strains.