P8: Biohydrogen production from lignocellulosic biomass in a single step process using DUSEL thermophiles

Pinewood, prairie cord grass (PCG), and corn stover (CS) are abundant lignocellulosic renewable materials in South Dakota and offer regional alternatives to corn for production of biofuels.  Therefore to save energy expenditure and costs for transport, pinewood, PCG and CS were used as feedstocks for biohydrogen production.  Hydrogen production from these regional lignocellulosic materials using mixed enrichment cultures isolated from the deep biosphere of Homestake Gold Mine was studied in anaerobic reactors at 60⁰C and pH 4, 7 or 10, and compared.  Thermo-mechanical pretreated prairie cord grass (PPCG) at 60°C and pH 10 yielded 29 ml H₂/g-dry PPCG, where as biohydrogen yields at pH 7 and 4 were 11 and 8 ml H₂/g-dry PPCG, respectively.  Untreated PCG at pH 10 gave maximum hydrogen yield (32 ml H₂/g-dry PCG) among all the treatments tested.  Some of these enrichment cultures also produced significant amounts of endoglucanases (43 units/L) and xylanases (930 units/L).  Some of these mixed cultures were characterized using 16S rDNA sequencing, and affiliated with the genera of uncultured, Clostridia, Bacilli, and Geobacilli.  One of the uniqueness of DUSEL thermophiles was that they produced significant amounts of hydrogen using untreated lignocellulosic biomass in a single step process (where saccharification and fermentation of biomass to hydrogen were carried out in a single reactor).  We are currently being optimizing the process parameters to develop a consolidated process for efficient conversion of lignocellulosic materials into hydrogen using DUSEL thermophiles.  The research would directly impact ongoing multiple steps conversion processes of lignocellulosic biomass to hydrogen.