nylon rope

Yeast converts sugar to make renewable nylon

A new hybrid way to convert sugar into nylon works at room temperature and uses inexpensive materials.

The technique combines a genetically engineered strain of yeast with a lead catalyst.

Previous attempts to combine biocatalysis and chemical catalysis to produce biorenewable chemicals have resulted in low conversion rates. That’s usually because the biological processes leave residual impurities that harm the effectiveness of chemical catalysts.

Zengyi Shao and Jean-Philippe Tessonnier, assistant professors of chemical and biological engineering at Iowa State University, are lead authors of a paper in the journal Angewandte Chemie International Edition that describes the successful hybrid conversion process.

Shao says it “opens the door to the production of a broad range of compounds not accessible from the petrochemical industry.”

Moving forward, the engineers will work to scale up their technology by developing a continuous conversion process, says Tessonnier.

How the technology works

Shao’s research group has created genetically engineered yeast—”a microbial factory,” she says—that ferments glucose into muconic acid. By applying metabolic engineering strategies, the group also significantly improved the yield of the acid.

Then, without any purification, Tessonnier’s group introduced a metal catalyst—lead—into the mixture and applied a small voltage to convert the acid. The resulting reaction adds hydrogen to the mix and produces 3-hexenedioic acid.

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After simple separation and polymerization, the engineers produced biobased, unsaturated nylon-6,6, which has the advantage of an extra double bond in its backbone that can be used to tailor the polymer’s properties.

The engineers say the hybrid conversion technology offers many advantages: The reaction is performed at room temperature, it uses a cheap and abundant metal instead of precious elements such as palladium or platinum, and the other compounds involved in the reaction are produced from water.

“We gave it a try and it worked immediately,” Tessonnier says. “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.”

The National Science Foundation, Iowa State’s Plant Sciences Institute, and the US Department of Energy’s Ames Laboratory supported the work.

Source: Iowa State University