Biosynthetic Pathway to Nylons
Biological production of cyclic precursors of nylon and related products avoids harsh chemicals and high heat.
Nylons are a class of widely used synthetic compounds known for their extreme toughness, strength, and elasticity. There are millions of tons produced annually for commercial applications as fibers (apparel, rubber reinforcement, flooring), shapes (electrical equipment, parts for cars, etc.) and films (mostly food packaging). Five- and six-member ring lactams are important commodity chemicals used as precursors in the manufacture of nylons. (Precursors are compounds that participate in a chemical reaction producing another compound). However, biological production of these highly-valued chemicals has been limited due to a lack of appropriate enzymes that form these lactam rings. An enzyme in the bacteria Streptomyces aizunensis has been enlisted to fulfill a crucial step in biological synthesis of these precursors.
Current commercial nylon production methods start with crude oil that requires energy intensive processes and harsh acidic reaction conditions. This is the first study to demonstrate a suitable enzyme for synthesis of lactams under microbial fermentation conditions for the manufacture of nylon. A Streptomyces enzyme enables five-membered, six-membered and even seven-membered ring formation at mild temperatures, resulting in the production of important industrial lactams via fermentation from biological molecules avoiding petroleum, harsh chemicals and heat.
Five- and six-member ring lactams are important commodity chemicals because they are used as precursors in the manufacture of nylons with millions of tons produced annually requiring harsh conditions. Biological production of these highly-valued precursors will reduce the need of petroleum and avoid toxic harsh conditions. However, biological production has been limited due to a lack of enzymes that carry out crucial steps at room temperature and pressure. DOE Joint BioEnergy Institute (JBEI) researchers demonstrated production of these precursors using an acyl-CoA ligase from Streptomyces aizunensis. This enzyme has a broad substrate spectrum and can cyclize linear amino acids into their corresponding cyclic lactam when expressed in Escherichia coli. Further metabolic engineering of the pathway lead to production of the lactams directly from the common amino acid lysine. This research advances DOE’s environmental and energy missions.
Joint BioEnergy Institute, Emeryville, California
This work was funded by the Joint BioEnergy Institute (http:// www.jbei.org/), which is supported by the US Department of Energy, Office of Science, Office of Biological and Environmental Research, through contract DE-AC02-05CH11231 between Lawrence Berkeley National Laboratory and the US Department of Energy and The Synthetic Biology Engineering Research Center (SynBERC) through National Science Foundation grant NSF EEC 0540879
J. Zhang, J.F. Barajas, M. Burdu, G. Wang, E.E. Baidoo, and JD. Keasling (2017) “Application of an Acyl-CoA Ligase from Streptomyces aizunensis for Lactam Biosynthesis” ACS Synthetic Biology [DOI: 10.1021/acssynbio.6b00372].