Fungal–bacterial interaction networks in lignocellulose degradation: an integrated ecological and mechanistic perspective

Lignocellulosic biomass (LCB) degradation is the process by which fungi and bacteria contribute complementarily at multiple organizational levels. This review integrates their enzymatic, ecological, and metabolic roles, and suggests the linkage structure between the microbial community dynamics and the design of synthetic microbial consortia. Fungi and bacteria form functionally coordinated interactions involving structural modification of substrates, microenvironmental regulation, and the continuity of metabolic pathways. These interactions enable degradation efficiencies that are not achievable under monoculture conditions. Recent omics-based studies conducted in LCB-rich environments show that this cooperative relationship is commonly observed in natural ecosystems. Furthermore, analyses of enzyme gene distributions and functional roles further indicate that key microbial members can be selected to construct simplified consortia without reproducing the full complexity of natural communities. Therefore, this review highlights a shift from viewing LCB degradation as a set of isolated enzymatic steps or single-strain activities to understanding it as a network-level biological process shaped by fungal-bacterial interactions. This perspective can provide a theoretical foundation for the rational design and optimization of microbial consortia in future bioconversion applications.