Isolation and characterization of a novel species and reclassification of Hitch . 2022 as comb. nov.

Obligately anaerobic, Gram-stain-negative, wavy rods, strains 17YCFAHCo10, 18YCFAH0.3Co2 and 19YCFAH0.3Co2, were isolated from faecal samples of healthy Japanese people. The three isolates showed the highest 16S rRNA gene sequence similarity to WCA3-601-WT-6H (99.2-100 %) and f_CXY (99.2-99.7 %). The 16S rRNA gene sequence analysis showed that the three isolates formed a cluster with WCA3-601-WT-6H. Strain 19YCFAH0.3Co2 formed a subcluster with the type strain of and did not form a cluster with the other two isolates. f_CXY also formed a cluster with WCA3-601-WT-6H and three isolates. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain 19YCFAH0.3Co2 and WCA3-601-WT-6H were higher (72 % dDDH and 97 % ANI) than the cut-off values for species delimitation, indicating that strain 19YCFAH0.3Co2 is . On the other hand, the dDDH and ANI values between strains 17YCFAHCo10 and 18YCFAH0.3Co2 and the type strain of were lower (<34 % dDDH and <87 % ANI) than the cut-off values for species delimitation, indicating that these two isolates are different species from . The percentage of conserved proteins and the average amino acid identity values support the assignment of the isolates to the genus . Strains 17YCFAHCo10 and 18YCFAH0.3Co2 could be distinguished from by their inability to ferment melibiose and ribose and lack of activity for -glucuronidase. In addition, the dDDH and ANI values between two strains (17YCFAHCo10 and 18YCFAH0.3Co2) and f_CXY were higher (>78 % dDDH and >97 % ANI), indicating these two strains and are the same species. As the genus has priority, is transferred to the genus as comb. nov. The type strain of is f_CXY (=JCM 34988=DSM 107528).