Upgrading the Hemicellulosic Fraction of Biomass into Biofuel
Résumé
Hemicelluloses are polymers composed mainly of C5 sugars (pentosans) . They constitute a
significant part of lignocellulosic biomass (LCB), as they can be up to 30% of the total
mass. The upgrading of the hemicellulosic components is thus a prerequisite for profitable
biofuel production from LCB. When LCB undergoes acid pretreatment, the
hemicellulose-derived fraction is mainly composed of monomeric pentoses (xylose,
arabinose) and oligomeric pentoses both resulting from the thermo-chemical hydrolysis. The
hemicellulosic fraction is not fermentable into ethanol by wild type strains of
Saccharomyces cerevisiae. Over the past 20 years, several groups have worked to
genetically modify this yeast in order to render it capable offermenting pentose
constituents. These efforts were met with varying degrees of success, especially in the
case of industrial substrates. In this paper, we describe two other possible ways of using
the hemicellulosic fraction, each of which may contribute to the economic viability of
biofuel production from LCB. The first one is its use as a carbon substrate for the
production of cellulases by Trichoderma reesei, since cellulases are needed for the
enzymatic hydrolysis of cellulose. The second is the AcetoneButanol-Ethanol (ABE)
fermentation using anaerobic bacteria of the genus Clostridium. The produced ABE mixture
has very interesting fuel properties and can be directly blended with gasoline.
Domaines
Physique [physics]
Origine : Publication financée par une institution
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