Comparison of plant biomass degradation module (PDM) occurrences in metagenome bins and isolate genomes of corresponding taxa. The colored circles at the leaf nodes of the tree denote the predicted occurrences of the different PDMs in the respective taxa or their subclades. The tree was constructed from the taxonomic assignments of the metagenome bins in our input set (see Methods). We then mapped the predicted occurrences of the PDMs in 28 different metagenome bins to the leaf nodes of the tree. If PDMs were identified in two or more bins, with one being a parental taxon to the other, the parent taxon is displayed. For example, predictions for Prevotella ruminicola were summarized with other predictions for the genus Prevotella. In addition, PDM occurrences in 403 isolate genomes of corresponding taxa were also mapped to the leaf nodes. The area of the colored circles for the isolate genomes was sized proportionally to the number of genomes for which the respective PDM was identified. The PDM predictions for the metagenome bins covered only five major taxonomic clades. The majority of PDMs in the metagenome bins were assigned to the orders Bacteroidales and Clostridiales. For the genomes, PDMs were identified from a broader range of taxa, including Actinobacteria, Firmicutes, Bacteroidetes, and Proteobacteria, in agreement with the estimated taxonomic range of potential cellulose-degrading species reported in . The differences in the taxonomic distributions of the identified PDMs between genomes and metagenome bins may partly reflect the abundance of Bacteroidales and Clostridiales degraders in plant biomass-degrading communities, but it is also likely that some PDMs were not identified in the metagenome bins because of the partial nature of the genomic information recovered.