Clostridium lapidicellarium sp. nov. and Clostridium moutaii sp. nov., two species isolated from fermentation cellar-producing sauce-flavour Chinese baijiu

<i>Clostridium</i> is an important microbial component in pit mud due to its ability to produce alcohol and short-chain fatty acids. This study presents the characterization and taxonomy of two Gram-stain-positive, strictly anaerobic, rod-shaped mesophilic bacterial strains, designated MT-113^T and MT-5^T, isolated from pit mud in a fermentation cellar used for producing sauce-flavour Chinese baijiu. Phylogenetic analysis based on genome and 16S rRNA gene sequences of strains MT-113^T and MT-5^T indicates their affiliation with the genus <i>Clostridium sensu stricto</i> (Cluster I of the Clostridia), with <i>C. luticellarii</i> FW431^T and <i>C. aromativorans</i> WLY-B-L2^T as the closest related species. The major cellular fatty acids (>10.0%) of both strains are C_{14 : 0} and summed feature 1 (iso-C_{15 : 1} h and/or C_{13 : 0} 3-OH). The G+C molar contents of the complete genomes for strains MT-113^T and MT-5^T are 35.84 and 32.74 mol%, respectively. The average nucleotide identity and average amino acid identity values between strains MT-113^T, MT-5^T, <i>C. aromativorans</i> WLY-B-L2^T and <i>C. luticellarii</i> FW431^T range from 79 to 85%. The primary products of glucose fermentation by MT-113^T are acetic, butyric and isovaleric acids, while those of MT-5^T are acetic, isobutyric, butyric and isovaleric acids. Based on their phenotypic, chemotaxonomic and phylogenetic characteristics, strains MT-113^T (=CGMCC 1.18018^T = JCM 36532^T) and MT-5^T (=CGMCC 1.18016^T = JCM 36530^T) are proposed as the type strains of two novel species of the genus <i>Clostridium</i>, namely <i>Clostridium lapidicellarium</i> sp. nov. and <i>Clostridium moutaii</i> sp. nov., respectively.