Date of Completion

4-28-2014

Embargo Period

4-28-2014

Keywords

Biomass, Biofuel, Cellulose, LF isotherm, Cellulase, Cellobiohydrolase I, Endoglucosidase II, Magnetic nanoparticle, TIRF, lasser-scanning fluorescence confocal microscopy, Surface mobility.

Major Advisor

Dr. Yao Lin

Associate Advisor

Dr. Rajeswari M Kasi

Associate Advisor

Dr. Mu-Ping Nieh

Field of Study

Polymer Science

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

Biomass is a sustainable and renewable energy resource that can be converted to liquid transportation fuels. However, conversion of cellulosic biomass into fuels is challenging due to its recalcitrant nature for enzymatic degradation. Inspired by the high efficiency of natural polycatalytic cellulase complex, cellulosome, we aim to create and investigate artificial cellulosomes with high activity, and systematically evaluate the fundamental principles that underlie their structure, dynamics and catalytic functions. To achieve our objective, we first studied the free cellulase system and found that it forms unique on-site assembly on cellulose surface which help it to overcome obstacle and regain processivity and thus significantly enhances its hydrolytic activity. This observation clearly suggests that free enzymes also uses complex form to enhance its activity which will help us to identify critical parameters required in a highly efficient artificial cellulase complex. Next, we developed a polycatalytic system consisting of cellulases covalently linked on the surface of colloidal polymers with a magnetic nanoparticle (MNP) core. MNP provides a convenient handle to separate the complex, while the colloidal polymer would serve as a benign scaffold to attach the enzymes. We investigated how the biochemical properties of free fungal cellulase changes on complex formation by studying its adsorption, diffusion and catalytic activity. We also identified the physical properties of scaffold which influences the catalytic efficiency of cellulase complex. Thus, the present studies address the key challenges in development of artificial cellulosome complex which is important for the economical production of biofuels from non-food sources.

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