Treponema peruense sp. nov., a commensal spirochaete isolated from human faeces

A Gram-stain-negative, obligatory anaerobic spirochaete (RCC2812(T)) was isolated from a faecal sample obtained from an individual residing in a remote Amazonian community in Peru. The bacterium showed highest 16S rRNA gene sequence similarity to the pig intestinal spirochete Treponema succinifaciens (89.48 %). Average nucleotide identity values between strain RCC2812(T) and all available Treponema genomes from validated type strains were all <73 %, thus clearly lower than the species delineation threshold. The DNA G+C content of RCC2812(T) was 41.24 mol%. Phenotypic characterization using the API-ZYM and API 20A systems confirmed the divergent position of this bacterium within the genus Treponema. Strain RCC2812(T) could be differentiated from the phylogenetically most closely related T. succinifaciens by the presence of alkaline phosphatase and alpha-glucosidase activities. Unlike T. succinifaciens, strain RCC2812(T) grew equally well with or without serum. Strain RCC2812(T) is the first commensal Treponema isolated from the human faecal microbiota of remote populations, and based on the collected data represents a novel Treponema species for which the name Treponema peruense sp. nov. is proposed. The type strain is RCC2812(T) (=LMG 31794(T)=CIP 111910(T)).