Isolation and Characterization of Kingella bonacorsii sp. nov., A Novel Kingella Species Detected in a Stable Periodontitis Subject

Members of the genus Kingella are mostly commensals of the oral cavity, but some of them are involved in invasive infections, especially in young children. This study provides new knowledge on the diversity of this genus by describing a novel species of Kingella isolated from a dental plaque sample from a 51-year-old man with a history of periodontitis. Morphological and chemotaxonomic characteristic were investigated using different growth conditions, pH and temperature. Cellular fatty acid methyl ester (FAME) analysis was performed by gas chromatography/mass spectrometry (GC/MS). Phylogenetic analysis based on 16S rRNA, orthologous average nucleotide identity (OrthoANI) and digital DNA–DNA hybridization (dDDH) relatedness were also performed. Strain Marseille-Q4569(T) was found to be a facultative aerobic, nonmotile and non-spore-forming rod-shaped bacterium that grows at 28–41.5 °C (optimum 37 °C), pH 5.5–8.5 (optimum pH 7.5) and 5–15 g/L of NaCl. The major fatty acids were Hexadecanoic acid (32.7%), 11-Octadecenoic acid (26.1 %) and 9-Hexadecenoic acid (21.3 %). Despite high 16S rRNA gene sequence similarity (98.72%) between strain Marseille-Q4569(T) and Kingella oralis strain UB-38(T), the degree of OrthoANI was at the limit of the cutoff (95.83%), and the degree of dDDH was lower (63.6%) than thresholds used to delineate prokaryotic species. Therefore, it is proposed that strain Marseille-Q4569(T) represents a novel species of the genus Kingella, for which the name Kingella bonacorsii sp. nov. is proposed (=CSUR Q4569).