Mechanism of biomass driving microbial community assembly in eco-engineering bauxite residues: Based on molecular...

Microbial community and dissolved organic matter (DOM) are two crucial factors controlling amelioration of biomass eco-engineering bauxite residues, yet the underlying coupling mechanism has remained poorly understood. This study investigated DOM molecular traits and chemodiversity as well as microbial diversity in various eco-engineering bauxite residues, by applying FT-ICR-MS and DNA sequences analysis. And the factors driving the specialization of DOM-microbe networks were identified with structural equation model (Semenov et al.). Our results demonstrated that exogenous organic amendments, particularly those incorporating vermiculite or fly ash, significantly enhanced DOM molecular richness and drove shifts in molecular composition. These changes regulated microbial assembly in eco-engineering bauxite residues by influencing the specialization of DOM-microbe interactions. Further random forest and structural equation modeling (SEM) analyses revealed that, besides environmental distal proxies, DOM molecular traits and microbial biodiversity also served as important proximal drivers regulating DOM-microbe interactions. The present study reveals that DOM compounds are informative for describing the pedogenesis of eco-engineering bauxite residues, and the combination of exogenous OM and fly ash could advance the eco-engineering pedogenesis of bauxite residues.