Abstract
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 Megasphaera elsdenii DSM 20460(T), Megasphaera indica NMBHI-10(T) and Megasphaera massiliensis 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 Megasphaera, for which we propose the name Megasphaera jansseni sp. nov. (type strain WILCCON 0056(T)=DSM 118846(T)=LMG 33760(T)). The genus Megasphaera belongs to the family Veillonellaceae. 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 Veillonellaceae. Based on a combination of comparative approaches, we propose reclassification and validation of 14 species within the family Veillonellaceae, refining the family to now comprise 4 validly published genera: Dialister, Megasphaera, Negativicoccus and Veillonella.