Reclassification of Eubacterium hallii as Anaerobutyricum hallii gen. nov., comb. nov., and description of Anaerobutyricum soehngenii sp. nov., a butyrate and propionate-producing bacterium from infant faeces

A bacterial strain designated L2-7(T), phylogenetically related to Eubacterium hallii DSM 3353(T), was previously isolated from infant faeces. The complete genome of strain L2-7(T) contains eight copies of the 16S rRNA gene with only 98.098.5 % similarity to the 16S rRNA gene of the previously described type strain E. hallii. The next closest validly described species is Anaerostipes hadrus DSM 3319(T) (90.7 % 16S rRNA gene similarity). A polyphasic taxonomic approach showed strain L2-7(T) to be a novel species, related to type strain E. hallii DSM 3353(T). The experimentally observed DNA-DNA hybridization value between strain L2-7(T) and E. hallii DSM 3353(T) was 26.25 %, close to that calculated from the genomes (34.3 %). The G+C content of the chromosomal DNA of strain L2-7(T) was 38.6 mol%. The major fatty acids were C-16(:0), C-16(:1) cis9 and a component with summed feature 10 (C-10(:1) c11/t9/t6c). Strain L2-7(T) had higher amounts of C-16:0 (30.6 %) compared to E. hallii DSM 3353(T) (19.5 %) and its membrane contained phosphatidylglycerol and phosphatidylethanolamine, which were not detected in E. hallii DSM 3353(T). Furthermore, 16S rRNA gene phylogenetic analysis advocates that E. hallii DSM 3353(T) is misclassified, and its reclassification as a member of the family Lachnospiraceae is necessary. Using a polyphasic approach, we propose that E. hallii (=DSM 3353(T)=ATCC 27751(T)) be reclassified as the type strain of a novel genus Anaerobutyricum sp. nov., comb. nov. and we propose that strain L2-7(T) should be classified as a novel species, Anaerobutyricum soehngenii sp. nov. The type strain is L2-7(T) (=DSM 17630(T) =KCIC 15707(T)).Peer reviewe