A bacterial strain isolated from a food processing drainage system in Costa Rica fulfilled the criteria as belonging to the genus Listeria, but could not be assigned to any of the known species. Phylogenetic analysis based on the 16S rRNA gene revealed highest sequence similarity with the type strain of Listeria floridensis (98.7 %). Phylogenetic analysis based on Listeria core genomes placed the novel taxon within the Listeria fleishmannii, L. floridensis and Listeria aquatica clade (Listeria sensu lato). Whole-genome sequence analyses based on the average nucleotide blast identity (ANI<80 %) indicated that this isolate belonged to a novel species. Results of pairwise amino acid identity (AAI>70 %) and percentage of conserved proteins (POCP>68 %) with currently known Listeria species, as well as of biochemical characterization, confirmed that the strain constituted a novel species within the genus Listeria. The name Listeria costaricensis sp. nov. is proposed for the novel species, and is represented by the type strain CLIP 2016/00682T (=CIP 111400T=DSM 105474T).
Keywords: AAI; ANI; Costa Rica; Listeria; POCP; new taxa; whole genome sequencing.