Microbial Factories

Engineers at Iowa State University created genetically engineered yeast that ferments glucose into muconic acid. Metabolic engineering techniques significantly improved acid production. They then introduced a lead catalyst along with a small voltage to convert the acid. The resulting reaction adds hydrogen to the mix and produces 3-hexenedioic acid.

A simple separation and polymerization produces bio-based, unsaturated nylon-6,6. The extra double bond in its backbone also means that the polymer’s properties can be changed as needed.

The hybrid conversion is possible at room temperature, uses a cheap and abundant metal instead of precious elements like palladium or platinum and the other compounds involved in the reaction are produced from water.

"The ideal bio-refinery pipelines, from biomass to the final products, are currently disrupted by a gap between biological conversion and chemical diversification. We herein report a strategy to bridge this gap with a hybrid fermentation and electro-catalytic process," wrote lead authors Zengyi Shao and Jean-Philippe Tessonnier, assistant professors of chemical and biological engineering at Iowa State University.

New Age Nylon

Instead of relying on petrochemicals to produce nylon products, the researchers’ developments created bio-renewable nylon with high conversion rates. The next step is to work on a continuous conversion process for mass production. Top uses for nylon include plastic fasteners and machine parts, cookware, and fabric.

"We gave it a try and it worked immediately," Tessonnier said. "The process does not need additional chemical supplement, and it works amazingly at ambient temperature and pressure, which is very rare for this type of process.”

For more information, see the published research in the journal Angewandte Chemie International Edition.