Conversion of biomass into ethanol generally involves three steps: pretreatment to open up biomass for enzyme action; enzymatic hydrolysis of the pretreated material to release sugars; and fermentation of the sugars by microorganisms, such as yeast, to produce ethanol. The second step, enzymatic hydrolysis, typically targets cellulose, which is the predominant component of biomass, while the sugars from hemicellulose are often released during pretreatment. The cellulose substrate is hydrolyzed by cellulase enzymes to produce glucose, which can be fermented by microorganisms into ethanol. Thus, the efficiency of the cellulose hydrolysis step directly impacts ethanol yields and/or conversion costs.
Typically, some of the cellulase enzymes that are added to the pretreated biomass to hydrolyze cellulose become bound to lignin (which makes up 15-30% of biomass). However, cellulase enzymes are unable act on lignin, and they are rendered useless by such binding. To compensate for this unproductive binding, additional quantities of cellulase must be added to the biomass, or else conversion efficiencies suffer. In either scenario, the cost/profit of the overall process becomes less favorable.
Dartmouth inventors have created a method for "tricking" lignin into binding proteins that are less expensive than cellulase. Blocking of the lignin binding sites by these less expensive proteins allows cellulase to efficiently degrade cellulose. Ultimately, less cellulase enzyme is necessary to produce near theoretical ethanol yields.
This technology is claimed in the issued United States Patent No. 7,604,976 and the published United States Patent Application No. 11/229,817. We are seeking an industrial partner interested in its commercialization. (Ref: J202)
Last Updated: 7/24/12