An obligately anaerobic strain, designated as A2931T, was isolated from oropharyngeal abscess puncture fluid of a patient sampled during routine care at a hospital and further characterized both phenotypically, biochemically and genotypically. This Gram-negative rod-shaped bacterium was moderately saccharolytic and proteolytic. Phylogenetic analyses of full-length 16S rRNA gene and whole-genome sequences revealed it to be best placed in the genus Prevotella, but to be only comparatively distantly related to recognized species, with the closest relationship to Prevotella baroniae (average nucleotide identity and digital DNA-DNA hybridization values both well below the generally accepted thresholds). Strain A2931T had a genomic DNA G+C content of 47.7 mol%. Its most abundant cellular long-chain fatty acids were anteiso-C15 : 0, iso-C15 : 0 and C16 : 0. Taken together, this polyphasic data suggests strain A2931T to represent a novel species within the genus Prevotella, for which the name Prevotella illustrans sp. nov. is proposed. The type strain is A2931T (=DSM 108028T=CCOS 1232T=CCUG 72806T). Interestingly, we found strain A2931T to correspond to the oral taxon Prevotella HMT-820 in the Human Oral Microbiome Database, as supported by overall genome relatedness index analyses >99 %. Thus, our work not only closes one of the gaps of knowledge about hitherto unnamed species isolated from humans, but also will facilitate identification of this taxon both in the clinical microbiology context and in research alike.
Keywords: Bacteroidetes; clinical isolate; novel species; phylogenomics; proteome-based phylogenomic analysis; whole-genome sequencing.