Is Nylon a 'Petrochemical' Product? Extracted from Microorganisms Instead

KAIST, Systems Metabolic Engineering Research Results
Development of Production Process for Nylon 5 Material Substance from Microorganisms

Nylon is commonly known as a petrochemical product. However, a domestic research team has developed a technology to produce nylon materials using microorganisms.

Nylon produced through petrochemicals. Photo reference.

On the 10th, the Korea Advanced Institute of Science and Technology (KAIST) announced that Dr. Han Tae-hee from the research team of Distinguished Professor Lee Sang-yeop in the Department of Bio and Chemical Engineering succeeded in developing a microbial strain that produces valerolactam, a monomer of nylon-5.

Valerolactam is an important monomer of nylon-5 and nylon 6,5. Nylon-5 and nylon 6,5 are types of nylon, the oldest synthetic fiber. Nylon-5 is a polymer composed of monomers with five carbon atoms, while nylon 6,5 is a polymer made of two types of monomers with six and five carbon atoms. Due to their excellent processability, light weight, and toughness, they are used across various industries, including clothing, badminton racket strings, fishing nets, tents, and gear components. Monomers are the materials used to make these polymers, and polymers are synthesized by linking monomers together.

Chemical production of valerolactam based on petrochemicals involves extreme reaction conditions and generates harmful waste. To address these issues, efforts are underway to develop microbial cell factories that produce valerolactam in an eco-friendly and highly efficient manner. Systems metabolic engineering, a research field founded by Professor Lee, is a key strategy necessary for developing effective microbial strains.

Development Strategy of Microorganisms Producing Valerolactam, a Nylon-5 Monomer. Image Source: Provided by KAIST

The research team constructed a synthetic metabolic pathway for valerolactam production in Corynebacterium, a type of bacteria mainly used for amino acid production, by manipulating the microbial metabolic pathways through metabolic engineering. This enabled the development of a microbial strain that produces high-value valerolactam using glucose biomass as a carbon source. In 2017, Professor Lee’s team proposed the world’s first strategy to produce valerolactam by metabolically engineering Escherichia coli. However, at that time, there were limitations such as low valerolactam production capacity and byproduct formation.

In this study, the team improved the valerolactam production capacity of the microorganism and additionally introduced systems metabolic engineering strategies to remove byproducts in the developed strain. They succeeded in reducing byproduct formation by deleting genes involved in major byproduct production and converting 5-aminovaleric acid, a byproduct and precursor, into valerolactam through gene screening.

The research team also strengthened the metabolic flow for valerolactam production by repeatedly inserting genes that convert 5-aminovaleric acid into valerolactam into the genome, achieving high-efficiency production of valerolactam at the world’s highest concentration (76.1 g/L). This is 6.17 times higher than the previous level.

The results of this study were published on the 12th of last month in the international journal Metabolic Engineering.

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