Metabolic Pathways of Biohydrogen Production from Biomass Sources

The transition toward sustainable energy systems requires the development of carbon-neutral fuels with low environmental impact. Hydrogen is widely recognized as a promising energy carrier due to its high gravimetric energy content and clean combustion profile, yet its industrial production remains dominated by fossil fuel–based processes. Biological hydrogen (biohydrogen) offers a renewable alternative by harnessing the metabolic capacities of microorganisms to convert biomass into hydrogen under ambient conditions. This article provides a comprehensive review of the metabolic pathways underlying biohydrogen production from biomass sources, emphasizing their biochemical mechanisms, regulatory features, genetic and metabolic engineering, and technological integration within modern biorefineries.