Hydrogen production by <i>Enterobacter cloacae</i> via dark fermentation using an agroindustrial residue, cashew apple bagasse

Abstract The use of biomass for the production of hydrogen gas (H 2 ) offers a promising pathway toward sustainable energy systems. However, effective H 2 production is still hindered by technological challenges, particularly in selecting appropriate feedstocks and optimizing production processes. In this study, cashew apple bagasse (CAB) – a lignocellulosic byproduct generated in large quantities during cashew juice and nut processing – was evaluated as a feedstock for H 2 production using Enterobacter cloacae and dark fermentation. The influence of different nitrogen sources on process performance was investigated. The highest hydrogen yield was obtained using an enzymatic hydrolysate of CAB (MCAB‐EH) supplemented with peptone as the nitrogen source, resulting in a productivity of 59.7 mL L −1 h −1 and a cumulative volume of 1432.4 mL H 2 per liter of hydrolysate after 24 h of fermentation. In the absence of supplementation, hydrolysate‐based fermentation yielded a productivity of 54.7 mL L −1 h −1 . In addition to hydrogen, the process generated acetic, lactic, and formic acids, ethanol, and 2,3‐butanediol as byproducts. These findings demonstrate the potential of E. cloacae to produce H 2 from agroindustrial residues such as cashew apple bagasse through dark fermentation. Nitrogen supplementation – particularly with peptone – also enhanced H 2 production, emphasizing its importance for improving microbial hydrogen generation and advancing renewable energy technologies.