17-08: Rheology studies of the role of thermostable cellulases and xylanase in the liquefaction of pre-treated wheat straw

Monday, April 29, 2013
Exhibit Hall
Pernille A. Skovgaard1, Maria J. Cardona2, Naradrapee Karuna2, Emilio Tozzi2, Matti Siika-aho3, Tina Jeoh4, Michael McCarthy2 and Henning Jørgensen1, (1)Faculty of Science, University of Copenhagen, Frederiksberg, Denmark, (2)Chemical Engineering and Materials Science, University of California, Davis, Davis, CA, (3)Biotechnology, VTT Technical Research Centre of Finland, Espoo, Finland, (4)Biological and Agricultural Engineering, University of California, Davis, Davis, CA
For processing of lignocellulosic biomass, the rheological behaviour during enzymatic hydrolysis is crucial at industrial relevant conditions, which usually implies high solids concentrations.  Recent studies have shown that the most pronounced changes in viscosity of lignocellulosic hydrolysates occur during the first hour after addition of enzymes. However, little is known about the interaction between various enzymes and biomass causing this quick viscosity reduction.

The aim of this study was to understand how various lignocellulolytic enzymes applied on two different pre-treated wheat straw materials impacted the rheological properties.  Pure and mixed thermostable cellulases were studied in combination with a pure xylanase to analyse their influence on viscosity and fiber properties.

Using a flow-loop setup with in-line magnetic resonance imaging (MRI) enabled continuous measurement of viscosity during hydrolysis. In addition, samples were frequently taken to follow the changes in fiber length and release of soluble sugars.

For all tested cellulases, viscosity dropped remarkably within the first hour of hydrolysis. Addition of xylanase to a cellulase mixture increased the rate of liquefaction, while the effect of xylanase added to an endoglucanase was negligible. No difference was observed in rheological properties when a cellulase mixture or a pure endoglucanase was applied with the same total enzyme loading.

The results of the viscosity measurements using MRI will be discussed in terms of results from fiber length analysis and the general saccharification. The results will provide an insight into the dynamic interaction between enzyme and biomass in early stage of hydrolysis.