Descriptions of Anaerotaenia torta gen. nov., sp. nov. and Anaerocolumna cellulosilytica gen. nov., sp. nov. isolated from a methanogenic reactor of cattle waste and reclassification of Clostridium aminovalericum, Clostridium jejuense and Clostridium xylanovorans as Anaerocolumna species.

Strictly anaerobic bacterial strains (FH052T and SN021T) belonging to clostridial cluster XIVa were isolated from a methanogenic reactor. Cells of the two strains were Gram-stain-positive, slender or curved rods producing terminal spores. The strains were slightly alkaliphilic. They fermented various carbohydrates including xylan and produced acetate, ethanol and H2. Strain SN021T decomposed cellulose. The genomic DNA G+C contents were 47.2 mol% for strain FH052T and 38.1 mol% for strain SN021T. The two strains had common cellular fatty acids such as C16 : 0, C16 : 0 dimethylacetal and C18 : 1ω7c dimethylacetal as major components. 16S rRNA gene sequence similarity between the two strains was 94.3 % and they shared closely related species such as Clostridium jejuense, Clostridium xylanovorans and Clostridium aminovalericum (92.6-95.7 % sequence similarity). Phenotypic and phylogenetic analyses suggested that these two isolates should be assigned to novel genera other than the genus Clostridium, and thus the genera Anaerotaenia gen. nov. and Anaerocolumna gen. nov. in the family Lachnospiraceae were proposed to accommodate them as Anaerotaenia torta gen. nov., sp. nov. for strain FH052T (=JCM 30820T=DSM 100431T) and Anaerocolumna cellulosilytica gen. nov., sp. nov. for strain SN021T (=JCM 30819T=DSM 100423T). For the three related Clostridium species, Anaerocolumna aminovalerica DSM 1283T (=JCM 11016T=ATCC 13725T) comb. nov., Anaerocolumna jejuensis HY-35-12T (=DSM 15929T=KCTC 5026T) comb. nov. and Anaerocolumna xylanovoransstrain HESP1T (=DSM 12503T=JCM 31057T) comb. nov. are proposed with emended descriptions of these species.