Bioenergy is derived from crops that harvest the energy in sunlight, carbon from CO2 in the air, and hydrogen from water. The energy is stored in various forms - starch in corn and cellulose, hemicellulose, and lignin in agricultural residues, as well as in soybeans. Fermentation-based processes that convert crop and grain residues into ethanol are the focus of LORRE's research. The Laboratory uses biotechnology to understand the metabolic pathways of microorganisms and mechanisms by which biocatalysts break down cellulosic residues into sugars. It applies molecular biology to direct metabolic pathways to more effectively produce ethanol, or to enhance properties of plants that feed fermentation processes. The Laboratory applies Bioprocess Engineering to integrate this fundamental knowledge into process technologies that transform renewable plant materials into transportation fuels. Success in this work depends upon teamwork across disciplines, as well as teamwork with industrial partners and cooperators at other universities and government laboratories.

Research

LORRE's work is integrative. It addresses preprocessing of biomass into a reactive form, carries out development of catalysts that mimic hydrolytic enzymes, and engineers yeast to transform sugars into ethanol and other bioproducts. This work addresses a suite of bioprocessing and fermentation technologies that are needed to achieve economic feasibility. The processing of cellulose, hemicellulose, lignin and starch components to biofuels and bioproducts presents unique challenges since the fundamental research must result in biological or biochemical processes that give high yields at low cost.

Pretreatments are being developed that make cellulose readily hydrolyzed so that enzymes or other hydrolysis catalysts are more effective. Genetically engineered yeast that ferments both hexose and pentoses to ethanol is being tested in industry. An energy efficient separation technique invented in LORRE and developed with an industry partner is used commercially.

The goal of preprocessing or pretreatment is to alter the macroscopic structure of plant biomass in order to make the nanostructure of the cellulose more accessible and susceptible to depolymerization (hydrolysis). Our current work is addressing the engineering of processes for large scale pretreatment, as well as understanding plant cell wall structure to enhance cellulose and hemicellulose hydrolysis. Bioprocesses for generating hydrogen from plant matter will depend upon this knowledge base.

The cost of enzymes is a critical factor for hydrolysis that can be used profitably in the industry. We are utilizing known structure/function relationships of cellulases, hemicellulases, and amylases in order to design biodegradable organic molecules which exhibit the selectivity of enzymes and may have lower costs. Solid acid catalysts and soluble diacid molecules are being investigated.

Fermentation of both glucose and xylose derived from cellulose and hemicellulose in nearly equal amounts must be addressed because native yeasts are not able to convert xylose to ethanol. LORRE is accomplishing genetic transformations that enable both glucose and xylose to be fermented to ethanol. Genetic modification of yeast to form other bioproducts is a future goal.

LORRE's multidisciplinary work integrates engineering with biotechnology to transition laboratory research into industrial settings that are capable of producing large volumes of biobased fuels. The goal is improving the productivity and lowering the cost of ethanol from biomass, while at the same time developing new technologies to generate other bioproducts, including hydrogen. Analysis of the economics of process improvements and the impact of such improvements on policies that encourage ethanol production and renewable energy are also beginning to become part of LORRE's activities.

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