Current Uses of Synthetic Biology
Naturally Replicating Rubber for Tires
Isoprene is an important commodity chemical used in a variety of applications, including the production of synthetic rubber. Isoprene is naturally produced by nearly all living things (including humans, plants and bacteria); the metabolite dimethylallyl pyrophosphate is converted into isoprene by the enzyme isoprene synthase. But the gene encoding the isoprene synthase enzyme has only been identified in plants such as rubber trees, making natural rubber a limited resource.
Currently, synthetic rubber is derived entirely from petrochemical sources. DuPont, together with The Goodyear Tire & Rubber Company, is currently working on the development of a reliable, high-efficiency fermentation-based process for the BioIsoprene™ monomer, and synthetic biology has played an important role in making this undertaking a reality.
Although plant enzymes can be expressed in microorganisms through gene transfer it is a long and cumbersome process, as plant genes contain introns and their sequences are not optimized for microorganisms. DNA synthesis and DNA sequencing have enabled the construction and rapid characterization of metabolically engineered microorganism strains to produce isoprene. Synthetic biology has enabled the construction of a gene that encodes the same amino acid sequence as the plant enzyme but that is optimized for expression in the engineered microorganism of choice. This method has provided massively parallel throughput which has made it possible to identify and track genetic variation among the various strains, providing insights into why some strains are better than others.
Continued use of synthetic biology should help refine DuPont’s biocatalyst for the production of BioIsoprene™ monomer.
Delivering Economic, Renewable BioAcrylic
Acrylic is an important petrochemical used in a wide range of industrial and consumer products. Acrylic ingredients make paints more durable and odor-free, adhesives stronger and longer-lasting, diapers more absorbent and leak-proof, and detergents better able to clean clothes. Today, petroleum-based acrylic is an $8 billion global market.
OPX Biotechnologies (OPXBIO) is developing renewable biobased acrylic to match petro-acrylic performance and cost but with a 75 percent reduction in greenhouse gas emissions. BioAcrylic from OPXBIO also will reduce oil-dependence and offer more stable prices.
The key to realizing these benefits, as with any biobased product, is a highly productive and efficient microbe able to use renewable sources of carbon and energy (for example corn, sugar cane, or cellulose) in a commercial bioprocess. A microbe that meets these criteria for BioAcrylic has not been found in nature, so OPXBIO is applying its proprietary EDGE™ (Efficiency Directed Genome Engineering) technology to redesign a natural microbe to achieve these goals. With EDGE, OPXBIO rapidly defines and constructs comprehensive genetic changes in the microbe to optimize its metabolism for economical production of BioAcrylic.
OPXBIO has advanced its BioAcrylic production process from pilot to large demonstration scale. The company has established a joint development agreement with The Dow Chemical Company, the largest producer of petro-acrylic in the United States, to bring BioAcrylic to market by 2016.
Making “Green Chemicals” from Agricultural Waste
Surfactants are one of the most useful and widely sold classes of chemicals, because they enable the stable blending of chemicals that do not usually remain associated (like oil and water).
Today, nearly all surfactants are manufactured from either petrochemicals or seed oils, such as palm or coconut oil. Worldwide production of surfactants from petrochemicals annually emits atmospheric carbon dioxide equivalent to combustion of 3.6 billion gallons of gasoline. Production from seed oil is greener, but there is a limit to the amount of seed oil that can be produced while protecting the rainforest. To address this problem, Modular has developed microorganisms that convert agricultural waste material into useful new surfactants. Dr. P. Somasundaran of the University Center for Surfactants (IUCS) at Columbia University finds that Modular’s surfactant is 10-fold more effective than a similar commercially available surfactant.
Modular has developed an engineered microorganism that converts soybean hulls into a surfactant for use in personal care products and other formulations. The hull is the woody case that protects the soybeans, and it cannot be digested by humans or other monogastric animals, such as pigs. The U.S. produces about 70 billion pounds of indigestible soy carbohydrate annually, and Modular seeks to upgrade this underutilized material by converting it into a variety of useful new chemical products. Modular’s surfactant program is partially supported with funds from the New Uses Committee of the United Soybean Board (USB), which seeks to expand soybean markets through the development of technology that enables the conversion of soy-based materials into new products.
