Biological hydrogen production from nitrogen‐deficient substrates

Dark fermentation of biomass using mixed bacterial cultures is one approach to producing renewable H 2 . The objective of this work was to determine if this approach could be applied to N‐deficient feedstocks using an N 2 ‐fixing mixed culture. A mixed culture produced up to 240 mL H 2 /g glucose (1.9 mol H 2 /mol glucose) from a medium initially lacking combined N. Yields from sugarcane were also promising: 170 mL H 2 /g volatile solids (7.5 mmol H 2 /g volatile solids). This approach could reduce economic and environmental costs of fermentative H 2 production, provide combined N for subsequent bioconversion stages, and improve effluent suitability for subsequent uses. Biotechnol. Bioeng. 2007;97: 435–437. © 2006 Wiley Periodicals, Inc.