Fig. 4

Conceptual diagram of carbon, sulfur, and nitrogen cycling in mangrove sediments dominated by the intra- and inter-cycles of the microbial active functional modules (mAFMs). The mAFMs surrounded by a dashed ellipse are organized by transcriptomic hubs/clusters of functional species and their partners filtered according to two conditions: (i) MIP \(\geqslant 5\) and (ii) maximal transcript abundance in the same layer as the hub/clusters of functional species (Table S9). Colors represent phyla (Fig. S7); lines show the connections with an MIP \(\geqslant 5\). The mAFMs carry out intra-cycling via microbial cooperation. Solid arrows denote the specific transformations; arrow thickness denotes the normalized transcript abundance of the genes within the corresponding pathway, showing the activity rankings among the five hub-centered mAFMs for each function category (provided in Table S10). The majority of C-, N-, and S-transformations are covered by the hub-centered mAFMs, except for the methane oxidation and production, which require the involvement of other species (Fig. S7, Table S9). Thus, extra mAFMs for methane production and oxidation are added on the left. The members in the modules responsible for methane oxidation could not form pairs with any MAGs in the community with an MIP \(\geqslant 5\). Cross-feeding among the modules and their exchange with the external environment promote biogeochemical cycling in the sediments