Analysis of 16S rRNA-encoding gene data for butyrate-producing communities. Panel A shows the cumulative result of obtained candidates associated with butyryl-CoA:acetate CoA-transferase (but; grey bar) and butyrate kinase (buk; white stripped bar). Below (B) individual compositions of communities are given. Results are corrected for multiple 16S rRNA-encoding gene copy numbers for individual bacteria. ? = butyrate production was shown for one strain of Subdoligranulum sp. as it is unclear whether all members of this genus have the potential to synthesize butyrate.