Correlation between abundances of butyrate-forming pathways (A), of terminal enzymes linked to the acetyl-CoA pathway (B), and of all individual taxa harboring a pathway (C). Correlation between abundances of butyrate-forming pathways (A), of terminal enzymes linked to the acetyl-CoA pathway (B), and of all individual taxa harboring a pathway (C). Analyses were performed on data derived from eight data sets (studies I to VI, VIII, and IX), where line width represents correlation strength, defined as the number of data sets displaying a correlation (P and Q < 0.05 and Spearman’s ρ > 0.4; a minimum of three correlations was required for connecting individual nodes; the dashed line in panel B represents correlations in two data sets). Node sizes reflect mean abundances (n = 813). Members of the Lachnospiraceae are indicated in bold, Ruminococcaceae are indicated in italics, and Bacteroidetes are underlined. Only taxa that were detected in >50% of samples were considered for analysis. but, butyryl-CoA:acetate CoA transferase; buk, butyrate kinase. Marius Vital et al. mSystems 2017; doi:10.1128/mSystems.00130-17