Project Number: 6435-41430-004-03
Project Type: Specific Cooperative Agreement

Start Date: Sep 19, 2006
End Date: Apr 30, 2008

Objective:
Research will focus on the following topics: (1) Quantification of rate enhancements for enzymes acting on cotton and other cellulosic materials in the presence of ultrasonic treatments. (2) Mathematical modeling of enzyme action on cotton and cellulosic substrates in the presence and absence of ultrasonic treatment. (3) Investigation of the importance of a cellulose binding domain for enzyme activity on cotton and other cellulosic substrates in the presence and absence of ultrasonic treatments. (4) Economic feasibility analysis of the potential for industrial scale ultrasonic treatments.

Approach:
Quantification of rate enhancements. Prior work has demonstrated that significant performance improvements can be obtained when enzymatic treatment of cotton is carried out in the presence of ultrasound 1,2. We hope to build on this work by measuring enzymatic rates on cellulose hydrolysis in the presence and absence of ultrasound. A number of different cellulosic materials will be treated with a variety of cellulase enzymes and the rates measured via HPLC quantification of sugar released over time. Endolytic cellulase activity can be quantified by measuring the increase in reducing sugar on the insoluble substrate. Conducting these experiments in the presence of varying amounts of ultrasonic energy will allow for the derivation of rate equations describing enzyme performance as a function of enzyme concentration, substrate availability and intensity of ultrasonic energy. Mathematical modeling. Equations from the above work will be utilized to yield an overall model describing enzyme action on cellulosic substrates. The individual enzymatic rate equations will be combined as a set of differential equations and numerically solved using mathematical modeling software such as MATLAB or Maple. This will allow for a variety of theoretical investigations aimed at examining the potential of ultrasonic treatments to enhance performance of enzymatic systems involving synergistic acting enzymes. Preparing and validating such a model will also greatly increase our understanding of the mechanism of ultrasonic enhancement of enzyme activity on cotton and other cellulosic substrates. Importance of the cellulose binding domain. Many enzymes that act on insoluble cellulosic materials such as cotton contain a cellulose binding domain (CBD) that serves to attach the enzyme to the surface of the substrate 4. This has been found to be critically important for high enzymatic activity on these substrates 5,6. It is of significant interest to examine the effect of ultrasound on the importance of the CBD. We plan to quantify ultrasound enhanced sugar release rates for both CBD containing enzymes and enzymes in which the CBD has been removed. Economic feasibility analysis. The modeling work will allow for the calculation of how much enzyme and ultrasonic energy would be required for acceptable industrial performance. This would facilitate the estimation the economic impact of incorporating an ultrasonic treatment. Further work will attempt to estimate the capital and operating cost of such an ultrasonic treatment. This should show how far this technology might be from application as well as indicate potential areas for further research.