Fig. 5.

Network layout showing the association between bacterial species and DOM formulae in the vDOM treatment. Bacterial species are shown in square nodes, and different bacterial classes are labeled with different colors (same color bar, in Fig. 2). Circle nodes represent assigned molecular formulae of CHO (blue), CHON (orange), CHOS (green) and others (dark gray, including CHONS formulae and not assigned ions). Direct connections were made between mass formulae and OTUs when the Spearmen’s rank correlation coefficient is strong r ≥ 0.9 (Positive network, upper) and r ≤ −0.9 (Negative network, lower), P ≤ 0.05. Size of square nodes are proportional to the in-connected degree. The OTU name tags were shown when square nodes with connections >100 in the positive network and >200 in the negative network (the others were listed in supplemental Tables 1 and 2). Assigned molecular formulae in each subnetwork were shown in supplemental Tables 3 and 4