A promising hybrid bio-hydrogen fermentation process based on light-material-microbe synergy strategy: Optimization, mechanisms and long-term trials

The study proposes a novel hybrid bioreactor that integrates light stimulation (LS) with Fe-rich zeolite and chlorinated polyethylene (CPE) as supporting materials, achieving sustained and robust H2 production over 80 days under mesophilic conditions. Compared with the conventional system, the hybrid reactor delivered a 1.8-fold H2 production, accompanied by strengthened metabolic activity and community resilience. Mechanistic insights unveiled a synergistic interaction among light, materials and microbiota, resulting in spatially structured fermentative niches and activation of key metabolic pathways. Specifically, LS enriched pyruvate formate lyase (PFL)- and pyruvate:ferredoxin oxidoreductase (PFOR)-mediated H2 evolution, while the supporting matrix facilitated biofilm formation, electron transfer and Fe redox cycling. The synergy further boosted flavin-based electron bifurcation (FBEB), enabling thermodynamically favorable H2 generation and ATP conservation. Importantly, simulated-solar experiment demonstrated that natural sunlight could substitute artificial illumination without performance loss, enabling energy-efficient and scalable applications. Overall, this study introduces a transformative framework that couples waste valorization with bioenergy generation, offering a viable and sustainable strategy for solar-assisted H2 production.