Microbial pathways for biohydrogen production: Advances, challenges, and future prospects

Rising oil costs, growing environmental concerns, and the pressing need for sustainable fossil fuel substitutes have all caused the globe to move firmly toward hydrogen as a possible future energy carrier. Microbial fermentation is a revolutionary method for producing hydrogen that not only uses readily accessible waste materials and neglected bioresources, such as forestry and agricultural wastes, but also blends in well with waste management and a circular bioeconomy. In this review, the metabolic characteristics of microorganisms that produce hydrogen are examined, along with the variables that affect production rates and yields, such as substrate specialization, enzymatic efficiency, and ambient circumstances. Important routes including photo fermentation, dark fermentation, and bio photolysis are discussed, along with their benefits, drawbacks, and potential for integration to increase overall efficiency. Critical bioprocess parameters, novel reactor topologies, and biomass pre-treatment methods are examined, with a focus on how they might improve hydrogen production and lessen process bottlenecks. Additionally, the potential of cutting-edge technologies like synthetic biology-driven microbial engineering and microbial electrolysis cells to transform hydrogen generation is assessed.Despite tremendous progress, problems including poor yields, scalability problems, high capital costs, and substrate competition still exist, calling for a multidisciplinary strategy that blends engineering tactics with biological breakthroughs.The necessity of coordinated efforts to improve microbial hydrogen production systems is ultimately highlighted by this analysis. This will help renewable hydrogen become a practical, scalable, and sustainable energy substitute for fossil fuels, promoting a cleaner and more resilient energy future.