A novel obligately anaerobic, non-spore-forming, rod-shaped, non-motile Gram-reaction-negative bacterium was isolated from infant faeces. The strain, designated NSB1T, was able to grow on rich media at 30–37 °C, in the presence of up to 2 % (w/v) Oxgall and 2 % (w/v) NaCl. Cells of strain NSB1T produced catalase, but not urease and indole. Aesculin was not hydrolysed. The strain was able to utilize d-glucose, lactose, maltose, mannose and raffinose as electron donors. When grown on d-glucose, the main metabolic end products were propionic and acetic acids, with a minor product being succinic acid. The major cellular fatty acids, iso-C15 : 0 and anteiso-C15 : 0, were present at a 1 : 1 molar ratio. The major menaquinone was MK-11. The DNA G+C content was found to be 38.5 mol%. According to 16S rRNA gene sequence analysis strain NSB1T is a member of the family
Porphyromonadaceae
, phylum
Bacteroidetes
. The closest relatives of the strain were
Barnesiella viscericola
(88.2 % identity) and
Barnesiella intestinihominis
(87.4 % identity). On the basis of phenotypic and genotypic properties of strain NSB1T we conclude that this strain represent a novel species in a new genus within the family of
Porphyromonadaceae
for which the name Coprobacter fastidiosus gen. nov., sp. nov. is proposed. The type strain of the species is NSB1T ( = DSM 26242T, = VKM B-2743T).