fig4

Figure 4. Global overabundance networks reconstructed from the case study. Networks for (A) healthy controls and (B) patients with colorectal cancer (CRC). Nodes and labels were plotted for nodes showing an overabundance greater than 1.35 ( + 35% average relative abundance in that group compared to the overall average relative abundance of that node in the dataset; represented in purple for HCs and yellow for CRCs in the plot). Node size is proportional to the overabundance value. Nodes colored in red represent the detected hubs by means of topological analyses of the global network, considering degree, betweenness, closeness and eigenvector centralities. The network layout was driven by the module detection with a mechanical spin-glass algorithm from the igraph R package, considering both positive and negative interactions. Such interactions between nodes are displayed as edges and colored according to the type of association (blue for positive interactions, red for negative ones), and line thickness is proportional to the adjacency values inferred during the network computation step. The figure highlights the relevance of networking as the CRC group clearly shows a different way of populating modules, with possibly harmful microorganisms particularly encompassed in the same module (i.e., module 3), which appears to be characteristic of this group. Network images were created using Cytoscape. CRC: Patients with colorectal cancer; HC: healthy control.