Veillonella nakazawae sp. nov., an anaerobic Gram-negative coccus isolated from the oral cavity of Japanese children

Abstract

Two strains of previously unknown Gram-negative cocci, T1-7^T and S6-16, were isolated from the oral cavity of healthy Japanese children. The two strains showed atypical phenotypic characteristics of members of the genus <i>Veillonella</i>, including catalase production. Sequencing of their 16S rRNA genes confirmed that they belong to genus <i>Veillonella</i>. Under anaerobic conditions, the two strains produced acetic acid and propionic acid as metabolic end-products in a trypticase-yeast extract-haemin medium containing 1 % (w/v) glucose, 1 % (w/v) fructose and 1 % (v/v) sodium lactate. Comparative analysis of the 16S rRNA, <i>dnaK</i>, <i>rpoB</i> and <i>gltA</i> gene sequences revealed that the two strains are phylogenetically homogeneous and comprise a distinct, novel lineage within the genus <i>Veillonella</i>. The sequences from the two strains shared the highest similarity, at 99.9, 95.8, 96.9 and 96.7 %, using the partial 16S rRNA, <i>dnaK</i>, <i>rpoB</i> and <i>gltA</i> gene sequences, respectively, with the type strains of the two most closely related species, <i>Veillonella dispar</i> ATCC 17748^T and <i>Veillonella infantium</i> JCM 31738^T. Furthermore, strain T1-7^T shared the highest average nucleotide identity (ANI) value (94.06 %) with type strain of the most closely related species, <i>V. infantium</i>. At the same time, strain T1-7^T showed the highest digital DNA-DNA hybridization (dDDH) value (55.5 %) with the type strain of <i>V. infantium</i>. The two strains reported in this study were distinguished from the previously reported species from the genus <i>Veillonella</i> based on catalase production, partial <i>dnaK</i>, <i>rpoB</i> and <i>gltA</i> sequences, average ANI and dDDH values. Based on these observations, the two strains represent a novel species, for which the name <i>Veillonella nakazawae</i> sp. nov. is proposed. The type strain is T1-7^T (JCM 33966^T=CCUG 74597^T).