Monday, May 4, 2009
11-09
Production of acetone-butanol from wheat straw hemicellulose hydrolyzates
Rémy Marchal, Benjamin Clément, Marcel Ropars, and Frédéric Monot. Department of Biotechnology, IFP, 1 & 4 avenue de Bois-Préau, 92852, Rueil-Malmaison, France
The cost-effective use of lignocellulosic raw materials requires the integrated production of value-added chemicals, transportation fuels and energy in a biorefinery concept. The pretreatment of wheat straw by steam explosion in mild acidic conditions results in the hydrolysis of hemicelluloses and solubilization of pentoses. Some Clostridium strains can utilize pentoses as a carbon source and excrete metabolic products such as acetone, butanol and ethanol (ABE or solvents). However, in addition to C5 sugars, the hemicellulose hydrolyzates obtained by this pretreatment may content toxic compounds, especially furanic and phenolic ones.
In order to define optimum conditions for ABE production from this material, the growth and solventogenic performances of some Clostridium strains on different wheat straw hemicellulosic hydrolyzates produced by steam explosion have been determined. Various C. acetobutylicum and C. beijerinckii strains from collections were compared in order to select the best ones for cultures in lab-scale reactors. Several concentrations of hemicellulose hydrolysates were used and removal of toxic compounds by overliming was sometimes necessary because of the sensitivity of Clostridium strains to some of them. In bioreactor, solvent concentration (more than 15 g/L) and productivity close to the performances obtained in a synthetic medium have been achieved.
This work was carried out in the framework of the Biosynergy project granted by the European Commission.
In order to define optimum conditions for ABE production from this material, the growth and solventogenic performances of some Clostridium strains on different wheat straw hemicellulosic hydrolyzates produced by steam explosion have been determined. Various C. acetobutylicum and C. beijerinckii strains from collections were compared in order to select the best ones for cultures in lab-scale reactors. Several concentrations of hemicellulose hydrolysates were used and removal of toxic compounds by overliming was sometimes necessary because of the sensitivity of Clostridium strains to some of them. In bioreactor, solvent concentration (more than 15 g/L) and productivity close to the performances obtained in a synthetic medium have been achieved.
This work was carried out in the framework of the Biosynergy project granted by the European Commission.