Two obligately anaerobic, Gram-stain-positive, rod-shaped bacteria were isolated from faecal samples of healthy humans in Japan. 16S rRNA gene sequence analysis indicated that these two strains (8CFCBH1T and 9CBH6) belonged to the genus Adlercreutzia, which is known as an equol-producing bacterium. The closest neighbours of strain 8CFCBH1T were Adlercreutzia equolifaciens subsp. equolifaciens DSM 19450T (98.6%), Adlercreutzia equolifaciens subsp. celatus do03T (98.4%), Adlercreutzia muris WCA-131-CoC-2T (96.6%), Parvibacter caecicola NR06T (96.4%), Adlercreutzia caecimuris B7T (95.3%) and Adlercreutzia mucosicola Mt1B8T (95.3%). The closest relatives to strain 9CBH6 were A. equolifaciens subsp. equolifaciens DSM 19450T (99.8%), A. equolifaciens subsp. celatus do03T (99.6%) and A. muris WCA-131-CoC-2T (96.8%). Strain 8CFCBH1T showed 22.3-53.5% digital DNA-DNA hybridization (dDDH) values with its related species. In addition, the average nucleotide identity (ANI) values between strain 8CFCBH1T and its related species ranged from 75.4 to 93.3%. On the other hand, strain 9CBH6 was considered as A. equolifaciens based on the dDDH and ANI values (>70% dDDH and >95-96% ANI). Strain 9CBH6 showed daidzein-converting activity, as expected from the result of genome analysis. The genome of strain 8CFCBH1T lacked four genes involved in equol production. Growing cells of strain 8CFCBH1T were not capable of converting daidzein. Based on the collected data, strain 8CFCBH1T represents a novel species in the genus Adlercreutzia, for which the name Adlercreutzia hattorii sp. nov. is proposed. The type strain of A. hattorii is 8CFCBH1T (=JCM 34083T=DSM 112284T).
Keywords: Adlercreutzia hattorii; equol non-producing bacterium; human faeces.