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Turning Plants Into Building Blocks

Turning a common crop into a renewably sourced building block requires the integration of biology with chemistry and engineering. In some cases, the best way to produce a high-performance building block is through the use of specially engineered microbes. Using a millennia-old agricultural practice as the primary influence for the biotechnology, DuPont has developed proprietary fermentation processes that create the versatile building blocks that can be used in the production of renewably sourced ingredients and materials. A good example of how this works is the process used by DuPont Tate & Lyle BioProducts, LLC (DT&L) which makes 1,3 propanediol (PDO) from corn sugar instead of petroleum.

Separation: Getting at the Carbohydrates

Currently, DT&L uses sugar (glucose) derived from cornstarch as the agricultural feedstock for creating propanediol. After harvesting, the crop goes through several milling and separating operations that break it down into smaller component parts and frees up the carbohydrates (starches) that can be used in subsequent steps.

First, the kernels are cooked for 24 hours at approximately 125 degrees centigrade, causing them to swell and soften. Second, the kernels are coarsely ground to loosen the germ from the endosperm — the part of the kernel where the starch is stored. Finally, the endosperm is ground to extract the starch and gluten. The starch is then treated with enzymes that convert it into glucose. The gluten meanwhile, undergoes further processing for use in feeds for farm animals.

Fermentation: A New Take on Old Technology

Fundamentally, DuPont utilizes the same science humans have used since ancient times to make bread, cheese, beer, and every other kind of food or drink that employs the use of live cultures; the only real differences between then and now are how we use the microorganism and what comes out of them.

In nature, there are naturally occurring yeasts that convert glucose into a chemical called glycerol. There are also naturally occurring microbes that convert glycerol into the chemical 1,3 propanediol. Through innovative metabolic engineering of biochemical pathways, DuPont and partner Genencor International have genetically spliced the desired traits from each organism into a host microbe. This unique microorganism now converts glucose to propanediol in a single step.

The patented microorganism is placed in a tank with water and fed glucose, along with vitamins, minerals and oxygen. After the organism ingests the glucose, it produces the three-carbon molecule, propanediol. Through distillation, the propanediol is separated from the water and purified, resulting in a clear, slightly viscous liquid. Currently, there are two product grades of renewably sourced propanediol being produced, DuPont Tate & Lyle Susterra™ and Zemea™.

Chemistry: Further Reactions

In some cases, the chemical building block created from the fermentation process can be used directly once it has undergone purification, but most building blocks require further thermo-chemical processing. After the fermentation stage, the resulting building block can be heated up and/or reacted with other chemicals (sometimes in the presence of a catalyst) to arrive at a useful, renewably sourced chemical building block.

DuPont Partnerships

DuPont believes that creating the technology to enable a sustainable world based on renewable resources cannot be accomplished alone. Therefore, DuPont will continually seek alliances and partnerships with companies that can bring world-class knowledge and expertise to help deliver transformative solutions for the environment and people everywhere. The following are examples of alliances and partnerships in which DuPont has engaged:

DuPont Tate & Lyle BioProducts, LLC — DuPont Tate & Lyle BioProducts is a joint venture between DuPont and Tate & Lyle. A world-leading provider of ingredients, ingredient solutions, and services to food, beverage and industrial customers, Tate & Lyle has unmatched bio-chemical knowledge and fermentation expertise of carbohydrates. The joint venture between DuPont and Tate & Lyle operates the first facility in the world that makes renewably sourced propanediol. Located in Loudon, Tennessee, it uses 40% less energy and reduces greenhouse gas emissions by 20% versus petroleum-based propanediol production. Production of 100 million pounds of renewably sourced propanediol in the Loudon plant is projected to save the equivalent of 13.5 million gallons of gasoline per year, or enough to fuel 24,000 cars annually. For additional information on the DuPont Tate & Lyle joint venture, click here.

Genencor International — Genencor, a wholly owned Danisco A/S subsidiary, is a leading diversified biotechnology company that discovers and develops biocatalysts and other bio-chemicals. DuPont partnered with Genencor to develop the microorganism technology that is used in the proprietary propanediol process.

Michigan State University — Michigan State University partnered with DuPont engineers to study the agriculture sustainability aspects of harvesting corn plants from the field in a comprehensive life cycle analysis. The results of this study are expected later in 2007.

DuPont™ Renewably Sourced™ Materials contain a minimum of 20% renewably sourced ingredient by weight.