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

Abstract

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 98.0-98.5 % 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 C16 : 0, C16 : 1cis9 and a component with summed feature 10 (C18 : 1c11/t9/t6c). Strain L2-7^T had higher amounts of C16 : 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=KCTC 15707^T).