Propionibacterium namnetense sp. nov., isolated from a human bone infection

International audienceA polyphasic taxonomic study was performed on two Gram-positive-staining, anaerobic, pleomorphic, rod-shaped strains isolated from human bone and tissue samples. Sequencing of the 16S rRNA genes revealed that the strains belong to a novel species within the genus Propionibacterium, most closely related to Propionibacterium acnes subsp. acnes and Propionibacterium acnes subsp. elongatum with similarity values of 98.4 % and 98.1 %, respectively. In addition, protein-coding genes for rpoB, recA and gyrB clearly separated the novel organism from all species and subspecies of the genus Propionibacterium. However, a DNA–DNA hybridization analysis between the novel organism and the type strain P. acnes ATCC 6919[T] revealed a value of only 61.1 %. Furthermore, whole genome analysis using the program OrthoANI gave a value of 88.5 %, which is significantly below the cutoff value of 95 % for species delineation. The major fatty acids were iso-C 15 : 0 , anteiso-C 15 : 0 and iso-C 17 : 0. The DNA G+C content of the type strain was 59.7 mol%. When taken collectively, phenotypic, molecular genetic, chemotaxonomic and phylogenetic information demonstrate that the organism represents a distinct, albeit close relative of P. acnes On the basis of the results presented, the organism represents a novel member of the genus Propionibacterium for which the name Propionibacterium namnetense sp. nov. is proposed. The type strain is NTS 31307302[T] (=DSM 29427[T] =CCUG 66358[T])