Description of Megasphaera jansseni sp. nov., a novel short- and medium-chain fatty acid-producing species isolated from faeces of a wild boar (Sus scrofa), and a taxonomic note on the family Veillonellaceae

A Gram-stain-negative, coccus-shaped, strictly anaerobic strain, named WILCCON 0056^T, was isolated from the faecal sample of a wild boar obtained from Pulau Ubin, Singapore (1.4126° N 103.9577° E). Comparative analyses based on 16S rRNA gene sequence similarity and whole genome relatedness indicated that strain WILCCON 0056^T was most closely related to <i>Megasphaera elsdenii</i> DSM 20460^T, <i>Megasphaera indica</i> NMBHI-10^T and <i>Megasphaera massiliensis</i> DSM 26228^T. However, their average nucleotide identity and digital DNA-DNA hybridization values only ranged from 84.6 to 92.6% and 24.2 to 47.8%, respectively, and were below the 95% and 70% thresholds for species delineation. Substantiated by further physiological, biochemical and comparative genomic analyses, strain WILCCON 0056^T represents a novel species within the genus <i>Megasphaera</i>, for which we propose the name <i>Megasphaera jansseni</i> sp. nov. (type strain WILCCON 0056^T=DSM 118846^T=LMG 33760^T). The genus <i>Megasphaera</i> belongs to the family <i>Veillonellaceae</i>. Members of this family are commonly found in the gastrointestinal tract of humans and animals and are well known for their ability to produce short-chain fatty acids such as propionic acid and butyric acid. This study further conducted a comprehensive taxonomic reassessment of the family <i>Veillonellaceae</i>. Based on a combination of comparative approaches, we propose reclassification and validation of 14 species within the family <i>Veillonellaceae</i>, refining the family to now comprise 4 validly published genera: <i>Dialister</i>, <i>Megasphaera</i>, <i>Negativicoccus</i> and <i>Veillonella</i>.