In the context of a study on the occurrence of Listeria species in an animal farm environment in Valencia, Spain, six Listeria-like isolates could not be assigned to any known species. Phylogenetic analysis based on the 16S rRNA gene and on 231 Listeria core genes grouped these isolates in a monophyletic clade within the genus Listeria, with highest similarity to Listeria thailandensis. Whole-genome sequence analyses based on in silico DNA-DNA hybridization, the average nucleotide blast and the pairwise amino acid identities against all currently known Listeria species confirmed that these isolates constituted a new taxon within the genus Listeria. Phenotypically, these isolates differed from other Listeria species mainly by the production of acid from inositol, the absence of acidification in presence of methyl α-d-glucoside, and the absence of α-mannosidase and nitrate reductase activities. The name Listeria valentina sp. nov. is proposed for this novel species, and the type strain is CLIP 2019/00642T (=CIP 111799T=DSM 110544T).
Keywords: AAI; ANI; POCP; isDDH; new taxa; whole genome sequencing.