Description of Paraclostridium bifermentans subsp. muricolitidis subsp. nov., emended description of Paraclostridium bifermentans (Sasi Jyothsna et al., 2016), and creation of Paraclostridium bifermentans subsp. bifermentans subsp. nov

Taxonomic studies of strain PAGU 1678(T), an obligately anaerobic, gram-positive, spore-forming bacterium isolated from biobreeding rat feces, were performed. This strain has been demonstrated to have the ability to exacerbate pathosis in a mouse model of dextran sulfate sodium-induced ulcerative colitis. Phylogenetic analysis based on the 16S rRNA gene showed high homology with Paraclostridium bifermentans. To clarify the correct taxonomic position of strain PAGU 1678(T), a comparative taxonomic study using P. bifermentans PAGU 2008(T) (JCM 1386(T)) and the closely related bacterial species P. benzoelyticum PAGU 2068(T) (LMG 28745(T)) was carried out. Despite the close similarity of 16S rRNA gene sequences, DNA-DNA hybridization between strain PAGU 1678(T) and P. bifermentans PAGU 2008(T) was 60.03% on average, average nucleotide identity was 96.17%, and it was shown to have different genomic sequences. Biochemically, strain PAGU 1678(T) could be differentiated from P. bifermentans PAGU 2008(T) by H2S production. Furthermore, strain PAGU 1678(T) was characterized by the presence of two phospholipids with different polarity on polar lipid analysis. In addition, strain PAGU 1678(T) differed from P. bifermentans PAGU 2008(T) in findings on whole-cell protein analysis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry. On the basis of these biochemical and genetic characteristics, a novel subspecies of P. bifermentans with the name Paraclostridium bifermentans subsp. muricolitidis subsp. nov. is here proposed, with PAGU 1678(T) (CCUG 72489(T) NBRC 113386(T)) as the type strain, which automatically creates P. bifermentans subsp. bifermentans subsp. nov. JCM 1386(T) (ATCC 638(T) DSM 14991(T)).