Inter-omic Spearman correlation networks. Pair-wise Spearman correlation was calculated for each operational taxonomic unit (OTU) and metabolite (module or un-clustered) pair. Any resulting correlations with q ≥0.2 were removed. The resulting correlation networks for the cecum (A) and sigmoid (B) data are shown. The key provided is applicable to both A and B. Blue edges represent negative correlation, while red edges represent positive correlation. Selected metabolites and metabolic modules from Table 4 are labeled.