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| Home : Volume 23 : Spring 1997 : | |
| Making micron-scale chemical factories | |
n October of 1938, DuPont's Dr. Charles M.A. Stine addressed a crowd gathered to see Katherine Hepburn at the World's Fair. He told them of DuPont's new filaments which were the world's first absolutely manmade fiber generated from "coal, air and water."
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The audience still looked on, dully.
But when they heard Stine hint that a major stocking mill had replaced
silk and was knitting nylon hosiery and that these new stockings felt
better, didn't bag or snag, and when they snagged they didn't run,
that passive audience stood and applauded.
The New York Times, Oct. 28, 1938; Time, Nov. 7, 1938. |
Nearly 50 years later, Associate Professor of Chemical and Biological Engineering Douglas C. Cameron is winning the applause for his work in engineering the metabolic pathway of 1-3 propanediol, an ingredient in the production of 3GT. 3GT is a form of polyester that combines the best qualities of nylon and PET (polyethylene terephthalate). But what is more striking than the material is the way it is made. Instead of coal, air and water, this fiber will be generated by engineered microorganisms.
Associate Professor Douglas C. Cameron in the biochemical engineering lab.
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Living cells can be thought of as sophisticated micron-scale chemical factories, says Cameron. A single cell can catalyze hundreds of reactions, regulate and control reaction sequences involving dozens of enzymes, perform its own maintenance and replicate itself. Metabolic pathway engineering (MPE) is the study of manipulating and managing these chemical factories. It has been called the "fourth wave" of biotechnology, following classical fermentation, recombinant protein production and protein engineering, and is of increasing importance for new biotechnological processes. Cameron had a hunch that 1,3-propanediol would be a good candidate for MPE.
Since the late 1980s, Cameron and his PhD candidates have been working on cloning the genes responsible for making 1,3-propanediol in microorganisms.
"In nature, there are organisms that change sugar into glycerol and organisms that change glycerol into 1,3-propandiol," Cameron explains. "We have cloned the genes for that natural metabolic pathway from glycerol to 1,3-propanediol and are working on placing that gene into an organism to change sugar directly into 1,3-propanediol".
Once isolated, the genes are transformed into a suitable host cell. There, the genes must be transcribed to mRNA's which must be translated into proteins. The proteins must have the proper activity and the pathway must function as a coordinated unit.
"We have proteins that produce 1,3-propanediol under a variety of conditions, " Cameron says. "The genes are a critical step."
Because a cell cannot function properly unless it is provided with the proper environment, the method in which the environment is maintained greatly influences the economics of a biological process. Therefore Cameron's research group is developing methods to efficiently maintain and control the cell environment. His group is now interacting with DuPont. DuPont provides unrestricted educational grants that help support chemical engineering laboratories.
Working on a similar path, DuPont and Genencor International have a joint agreement to develop a biological process for 1,3-propanediol. The new technology will potentially enable production of 1,3-propanediol at a cost approaching that of ethylene glycol, the monomer used to produce PET. At the same time, this new 3GT polyester can be produced in existing DACRON® polyester fiber production facilities with only minor modifications, and in planned new nylon fiber facilities.
"This is truly an extraordinary application of biotechnology," Cameron
says. "DuPont and Genencor now have the ability to produce a useful
polymer intermediate using an inherently 'green' process starting from
inexpensive carbon sources such as corn starch."
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Date last modified: Wednesday, 09-Apr-1997 12:00:00 CDT
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