The scale bar shows 5 nucleotide substitutions

per 100 nucleotides. Number of clones in parentheses follows label of either common OTUs (framed), OTUs solely from CL-B1 (green) or CL-B2 (purple). Most of the clones fell see more within the Clostridiales, representing members of seven different bacterial families. A total of 186 clones of this class learn more (31%) belonged to OTU-3 and were highly related (<1% nucleotide divergence) to Clostridium hiranonis TO-931T. Within the Clostridiaceae a high nucleotide similarity was also found for OTU-2, which grouped 65 clones closely to Clostridium perfringens ATCC 13124T, and for OTU-34, which clustered with Clostridium fallax ATCC 19400T. However, the latter only consisted of one clone and displayed a low bootstrap value of 56% at its node. For OTU-9, OTU-32 and OTU-5, high bootstrap values (92%, 100% and 95%) and a low nucleotide divergence (1%) indicated their close phylogenetic affiliation to Clostridium

glycyrrhizinilyticum ZM35T, Clostridium colicanis DSM 13634T S63845 molecular weight and Clostridium glycolicum DSM 1288T, respectively. The remaining five OTUs within the Clostridiaceae family (OTU-31, OTU-1, OTU-30, OTU-33 and OTU-21) clustered under lower bootstrap values with their respective type strains. The Ruminococcaceae family was also well represented by four OTUs of which OTU-7 constituted 89 clones closely related to Ruminococcus gnavus ATCC 29149T. The high bootstrap Chloroambucil value (100%) at the node of cluster OTU-35 and Hydrogenoanaerobacterium saccharovorans SW512T suggests a reliable phylogenetic positioning although there was less than 90% sequence similarity between both. The remaining OTU-19 and OTU-20 included only 6 clones clustering

at 5% nucleotide divergence with Ruminococcus gnavus ATCC 29149T and Ruminococcus torques ATCC 27756T, respectively. The Peptococcaceae family was only represented by OTU-6, which included 34 clones and exhibited a low sequence similarity (80%) with the nearest type strain, Desulfonispora thiosulfatigenes DSM 11270T. Moreover, the low bootstrap value (63%) questions the phylogenetic position of OTU-6 in this tree. The remaining families Lachnospiraceae, Enterococcaceae and Peptostreptococcaceae were represented by 6 different OTUs which together encompassed 6% of all sequences allocated to the Clostridiales. The unclassified Clostridiales, Incertae Sedis XIV, harbored 18% of all sequences across three OTUs and were all affiliated to the genus Blautia. However, only OTU-10 showed 1% sequence divergence to its type strain Blautia hansenii JCM 14655T, whereas OTU-12 and OTU-13 differed at least 4% from the closest relative Blautia glucerasei HFTH-1T. Based upon the previously proposed classification of Clostridium spp. in phylogenetic clusters [34], Clostridiales sequences from this study fell into three clusters.