Species-level quantification of Faecalibacterium spp. in feces of healthy

Faecalibacterium prausnitzii has been considered as one of the predominant microbes in gut microbiota of healthy human adults. Moreover, due to its beneficial metabolites and its reduced population in patients with various disorders, this organism has been regarded as one of the key gut microbes in human health. However, following recent revisions in the taxonomy of the genus Faecalibacterium and F. prausnitzii, the reported population distribution and health benefits of this species have become unclear. In the present study, the population of nine species-level taxonomic groups (hereafter referred to as species) within Faecalibacterium was quantified at the species level in the feces of healthy Japanese adults (n=88).