ARF14 - Biofuel from degradation of cellulose and chitin

Researcher:

Dr. Anthony Clarke, Dept. of Molecular and Cell Biology, University of Guelph

Objectives:

Long term:

To achieve a fundamental understanding of the mechanisms that are relevant for the development of cellulose de-polymerization and to engineer new enzymes with improved de-polymerization efficiencies and selectivity for different biomass substrates.

Short term:

1. Use genetic engineering to produce catalytically-inactive enzymes with linking polypeptide tethers of differing lengths to intact carbohydrate-binding modules (CBMs).

2. Apply surface specific techniques, such as atomic force microscopy, scanning tunneling microscopy and infrared reflection absorption spectroscopy to achieve an understanding of the mechanism of binding of the inactive enzymes to a cellulose fibre at the molecular level.

3. Use surface Plasmon resonance and quartz microbalance techniques to study the kinetics of binding of the inactive enzymes to cellulose fibres and their digestion by catalytically-active homologs to determine the rate determining step of the de-polymerization reaction.

4. Engineer the most efficient enzyme for cellulose de-polymerization and to study it under variable temperature for different structures of cellulose fibres.

5. Assess the performance of the best enzymes in a larger scale experiment carried out in a bioreactor and work with Iogen towards commercialization of these enzymes.

Expected Benefits:

Development of new strategies for engineering of more efficient enzymes for depolymerization of cellulose.

Summary of Research Results:

Cellulose ethanol is made by treating fibre with enzymes to yield sugars that are then fermented to ethanol for fuel. But, turning plant cellulose into ethanol is more difficult than the process used for corn ethanol, and finding ways to make this process more efficient has become like "the holy grail of agriculture."

The densely packed cellulose fibres are what lend plants their toughness, allowing a tree to grow hundreds of feet high without falling over. Although the inflexibility of thecellulose makes it difficult to break down, there are natural enzymes that can degrade the plant structure. Cows, for example, can digest the plant fodder because their guts contain specially evolved microbes able to gnaw through cellulose.

The researchers hope to copy this natural breakdown right down to the molecular level by combining a range of expertise and tools, from genetically engineered microbial enzymes to nanoscale microscopy and imaging.

By learning how nature breaks down cellulose in biomass and improving on that process,they hope to help the biofuels industry make a product that's greener and more economically viable.

"We're trying to help with the efficiency of the process. If we can see this better, we can study the efficiency better."