Proteins at heterogeneous (lignocellulose) interfaces

Lignocellulosic biomass is a renewable resource capable of addressing the increasing worldwide demand for energy and the movement toward low carbon footprint, liquid transportation and aviation biofuels. Purposely grown energy crops (wood and grasses) and crop residues (corn stalks, sugarcane bagasse, and wheat straw) are available for conversion to biofuels if attractive process economics are achieved in hydrolyzing these lignocellulosic materials to sugars and converting the sugars to biofuels and bioproducts. Cellulase enzymes that hydrolyze cellulose to glucose currently contribute operating expenses of $0.15-$0.20 per liter of ethanol out of a total of $0.53. The goal is to decrease enzyme costs to 3-5 ¢/L. The high cost is in part due to the high loading of cellulases needed to make up activity losses when the enzymes bind to lignin rather than the cellulose substrate that is located in close proximity to the lignin. We address the concept of using liquid chromatography columns packed with biomass to efficiently probe partitioning of cellulases and other proteins on the surfaces of various forms of lignocellulose. The correlation of elution profiles to fundamental adsorption behavior provides a pathway to a deeper understanding of inhibition of cellulose hydrolysis due to interactions of proteins at heterogeneous lignocellulosic interfaces.