Monday, May 2, 2011
Grand Ballroom C-D, 2nd fl (Sheraton Seattle)
Commercialization of enzymatic biomass-to-ethanol processes has been limited, at least in part, due to the large amount (and therefore high cost) of enzymes required to achieve fast, efficient hydrolysis of the cellulosic component. The accessibility of cellulose to cellulase is thought to be one of the key substrate properties that influences the efficiency of enzymatic hydrolysis. However, even when using model cellulosic substrates, it is still not completely clear how changes in the available surface area of cellulose affect the enzymatic hydrolysis rate/extent. This is likely due to the apparent ability of cellulases to recognize fine substructures within the structurally heterogeneous cellulosic substrate combined with the reality that traditional techniques for measuring surface area cannot accurately differentiate between the accessibility of the different cellulosic substructures. In the work that will be presented, several techniques have been used to monitor changes in the organization/accessibility of model cellulosic substrates treated with disruptive/swelling agents. These techniques have been successfully used to quantify changes in the total surface area of cellulose accessible to cellulases after treatment. They have also been used to monitor the effects of the treatments on the accessibility of different cellulosic substructures. We will describe how changes in the accessible surface area affect hydrolysis rates and how this work enhanced our understanding of the complex relationship between the accessibility of cellulose and enzymatic hydrolysis