Understanding and Optimizing Enzyme Efficiency for Cellulose Biodegradation

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Petroleum depletion, energy shortage, and environmental deterioration are major global issues. We urgently need to develop technologies for converting renewable biomass, such as agricultural residues and forestry byproducts, into cleaner biofuels, chemicals and other bioproducts. However, the major bottle-neck in biomass conversion is the production cost of efficient bioconversion enzymes. My research program aims to engineer new types of bacteria and establish co-culture environments that will make the production of bioconversion enzymes faster and more cost-effective, leading to new opportunities for clean energy in Canadian industry. Some bacteria and fungi that are resistant to extreme environmental conditions are known to produce highly efficient enzymes for converting biomass into biofuel precursors and other products. The anaerobic bacterium Clostridium thermocellum offers great potential for producing highly effective bioconversion enzymes: a complex multienzyme structure called cellulosome. Our research program will focus on engineering more efficient cellulosome-producing strains of Clostridium. This will greatly increase enzyme production, reducing the cost of biorefining. However, while Clostridium is an excellent producer of cellulosomes and fermenter of 6-carbon sugars, it cannot ferment 5-carbon sugars derived from hemicelluloses during hydrolysis. Our novel approach will introduce a 5-carbon sugar-fermenting bacterium, Thermoanaerobacteria saccharolyticus, to create an optimized co-culture system that will greatly increase lignocellulosic hydrolysis rates by simultaneously fermenting 6-carbon and 5-carbon sugars. By combining these two bacterial cultures we will create a new and highly efficient enzyme production technology. The co-culturing of Clostridium and Thermoanaerobacteria has never been undertaken, and our research program will therefore set a framework for a much larger research program that aims to develop more efficient techniques for enzyme production for biorefining industries. Our research will expose all trainees to advanced biotechnology techniques and equipment. They will gain the techniques and abilities required for future independent work. Moreover, they will develop the skills, knowledge and techniques in the development of scalable bioproduction, skills that will be essential in reducing our dependence on fossil fuels, lowering greenhouse emissions and making use of Canada's abundant and renewable forest biomass.