Community assembly enables a microbial metabolic relay governing the emergence of pollutant degradation
Pollutant degradation in microbial communities often emerges inconsistently even under identical chemical conditions, and the ecological mechanisms underlying this functional divergence remain poorly understood. Using atrazine as a model xenobiotic compound, we investigated how microbial community assembly shapes the emergence of degradation capacity during chemical enrichment. Replicated enrichment experiments revealed a sequential assembly process consisting of disturbance, tolerance filtering, and subsequent divergence in community trajectories. Although potential degraders were detected across all enrichment lines, efficient degradation developed only in communities where prior assembly reorganized microbial interaction networks. Time-resolved coupling of taxa and metabolites further revealed a microbial metabolic relay, in which distinct populations performed successive steps of the degradation pathway. These findings demonstrate that pollutant degradation is an emergent property of community assembly, arising from assembly-enabled metabolic interactions rather than the mere presence of degraders.