Fuente: PubMed "rice" Water Res. 2026 Aug 10;307:126669. doi: 10.1016/j.watres.2026.126669. Online ahead of print.ABSTRACTExcessive nitrogen (N) discharge from agriculture and industry causes severe ecological harm. Moreover, conventional nitrogen removal processes often generate N2O, adding to the environmental burden. While algal-bacterial consortium has emerged as a low-carbon alternative to address these issues, the bioenergetic mechanisms governing their N2O-mitigation performance remain poorly understood. In this study, a Chlorella sorokiniana-Paracoccus denitrificans consortium was established to clarify the mechanism underlying enhanced N₂O mitigation. The consortium achieved superior total nitrogen removal (86.6%) while mitigating N2O emissions by 67.7% compared with the bacterial monoculture system, effectively overcoming the metabolic limitations of denitrification. The consortium established a coordinated nitrogen-metabolic network, which not only upregulated assimilatory pathways but, crucially, enhanced the expression of downstream reductase genes to prevent intermediate accumulation. Comprehensive analysis revealed that the enhanced nitrogen transformation and N2O mitigation in the MIC&BAC system were driven by a dual mechanism involving assimilation shunt and downstream denitrification reinforcement. In this mechanism, algal-bacterial coupling increased ATP and NAD(P)H availability and promoted nitrogen assimilation into biomass, thereby reducing the nitrogen flux entering the denitrification pathway. Meanwhile, improved reducing-equivalent supply and electron-transfer regulation strengthened terminal N2O reduction to N2. Crucially, we identified a key extracellular "redox capacitor" mechanism mediated by extracellular polymeric substances (EPS). The specific enrichment of humic/fulvic acid components and c-type cytochromes formed a redox-active interfacial network with enhanced charge-transfer capacity. The enhanced extracellular electron transfer (EET) process supported more electron delivery to downstream denitrifying reductases while minimizing N2O accumulation. These findings provide new insights into the bioenergetic and electron-transfer mechanisms governing algal-bacterial symbiosis.PMID:42624061 | DOI:10.1016/j.watres.2026.126669