Test Beds

Medium chain length fatty acid (10–12) will be used as the test bed to guide the initial design of the microbial production system (accumulation of laurate in the fermentation broth at high concentrations has been reported by the overexpression of a plant thioesterase). As more KS, MKS, and TE systems with different substrate and chain length specificity become available, the microbial production system will be extended to the synthesis of hydrocarbons with 3-ene-2-one functionality from glucose.

The combined efforts of Thrusts 1 and 2 will lead to the development of new biological catalytic approaches for the synthesis of hydrocarbons with 3-ene-2-one functionality. For example, a long-term goal would be the synthesis of such compounds as 3-penten-2-one or 3-heptene-2-one.

This class of compounds presents a variety of opportunities for the application of selective conversion by chemical catalysts. For example, catalysts can be designed for selective hydrogenation of the C=C bond to produce ketones; catalysts can be prepared for the selective hydrogenation of the C=O bond to produce unsaturated alcohols, perhaps followed by the dehydration of the alcohol to produce dienes. Other options for chemical catalysts are the use of these compounds as nucleophiles in aldol-condensation, either at the terminal methyl group (carbon #1) or at the allylic position (carbon #4).

For the purposes of this test bed, we have selected the chemical catalytic conversion of the 3-ene-2-one compounds to dienes.

Dienes can be used directly in the polymer industry, and they can undergo a variety of subsequent catalytic conversions to compounds, such as olefins and diols, thereby providing an excellent platform for chemical applications.

This method of combining biological and chemical catalysts provides a strategy for the synthesis of compounds that are similar to high-volume chemicals currently derived from petroleum, thus providing an example of a commodity chemical application. However, an important aspect of this approach is that it leads to a new synthetic route for the production of dienes attached to controlled R-groups, thereby providing a design tool for the synthesis of new monomers for the polymer industry.

Integration across the thrusts will be facilitated by having several target molecules. Thus, in addition to the dienes target, CBiRC will have a second integrated test bed that will target α-olefins. Additional targets will be developed in the future with input from CBiRC’s advisory board and our industrial partners.

The test beds for production of dienes and α-olefins will drive integrative research across the three thrust areas, thereby demonstrating technology integration for CBiRC. It is also important to note that at the Knowledge Base and Technology Base levels of CBiRC, as outlined in the 3-plane diagram, we expect important contributions to the transformation of the chemical industry through novel biological and chemical catalysts, new catalytic reaction systems, and tools for microbial metabolic engineering. Therefore, we expect successes from the interdependence of the thrusts as well as within each individual thrust.