CS (5% w/v) were soaked in ammonium hydroxide (10% v/v) at 70°C for 22h to remove lignin, and then subjected to saccharification of the cellulose and xylan fractions for 72h at 50°C, pH 5.0 by enzymatic cocktail prepared with commercial enzymes. The resulting CS hydrolyzate was detoxified with activated charcoal, and used as carbon and energy source in fermentations by C. butyricum. After 72 hours 83.6% of the initial glucose and xylose were consumed, yielding 1.92 mol.mol-1 of H2. The ratio of H2/CO2 in the biogas produced was 1.3, and the hydrogen volumetric production rate attained 449 ml.l-1day-1. These results demonstrate the adequacy of CS for the biological production of hydrogen.
The strategy proposed in this work for CS upgrading holds a promise for future optimization of the physical-chemical/enzymatic treatments and detoxification process and bioconversion yield.
Acknowledgments The authors gratefully acknowledge the financial support of the Project FCT-CNR – Italia 128585955528141.