Paraclostridium benzoelyticum gen. nov., sp. nov., isolated from marine sediment and reclassification of Clostridium bifermentans as Paraclostridium bifermentans comb. nov. Proposal of a new genus Paeniclostridium gen. nov. to accommodate Clostridium sordellii and Clostridium ghonii.

Twenty-three rod-shaped, endospore-forming, Gram-stain-positive, obligately anaerobic bacteria were isolated from different marine sediment samples of Gujarat. All 23 strains shared 16S rRNA gene sequence similarity of ∼100 %. Strain JC272T was designated the type strain and shared highest sequence similarity with Clostridium bifermentans ATCC 638T (99.8 %), Clostridium ghonii JCM 1400T (98.0 %), Clostridium sordellii ATCC 9714T (97.9 %) and other members of the genus Clostridium ( < 96.4 %). C16 : 0, C18 : 0, C17 : 0, C16 : 1ω9c and iso-C16 : 0 were the major (>5 %) fatty acids. Strain JC272T contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and two unidentified amino lipids. Genome-based analysis of average nucleotide identity (ANI) and in silico DNA-DNA hybridization (DDH) of strain JC272T with C. bifermentans ATCC 638T yielded values of 94.35 and 58.5 ± 2.8 %, respectively. The DNA G+C content of strain JC272T was 28.3 mol%. Strain JC272T together with C. bifermentans were found to fall outside Clostridium rRNA cluster I considered as Clostridium senso stricto. Based on ANI value, in-silico DDH, and distinct morphological and physiological differences from the previously described taxa, we suggest that strain JC272T represents a novel species of a new genus in the family Clostridiaceae, for which the name Paraclostridium benzoelyticum gen. nov., sp. nov. is proposed. The type strain is JC272T ( = KCTC 15476T = LMG 28745T). It is also proposed to transfer C. bifermentans to this new genus, as Paraclostridium bifermentans comb. nov. (type strain ATCC 638T = DSM 14991T = JCM 1386T). The genus Paeniclostridium gen. nov. is proposed to accommodate C. sordellii and C. ghonii as Paeniclostridium sordellii comb. nov. (type strain ATCC 9714T = LMG 15708T = JCM 3814T) and Paeniclostridium ghonii comb. nov. (type strain ATCC 25757T = DSM 15049T = JCM 1400T).