Genome-Resolved Insights into Ni/Fe₂O₃ Nanocatalyst-Enhanced Dark Fermentative Hydrogen Production from Food Waste

Abstract

Bimetallic nanocatalysts have shown promise in enhancing fermentative biohydrogen (bioH₂) production; however, the underlying microbial and metabolic mechanisms remain insufficiently understood. In this study, food waste-based dark fermentative bioH₂ production was significantly enhanced by the addition of a synthesized Ni/Fe₂O₃ bimetallic nanocatalyst, achieving a hydrogen yield increase of up to 55.65% compared to the control. The presence of Ni/Fe₂O₃ improved system pH stability, conductivity, and electron transport capacity, indicating enhanced fermentative activity. Genome-centric metagenomic analysis revealed that the catalyst reshaped the microbial community and metabolic functions by promoting Clostridium species as dominant hydrogen-producing bacteria and enriching genes associated with carbohydrate metabolism, complex saccharide hydrolysis, nutrient transport, glucose phosphorylation, and electron transfer pathways. These findings uncover a previously unrecognized catalytic role of Ni/Fe₂O₃ in regulating microbial community structure and metabolic pathways, providing genome-level insights into catalyst-microbe interactions and offering a mechanistic foundation for advancing food waste-derived biohydrogen production.