Bio-based Production of Caprolactam

Introduction

Caprolactam is the key building block for nylon-6, a widely used synthetic polymer in textiles, automotive parts, electronics, and engineering plastics. Traditionally, caprolactam is produced from cyclohexanone, derived from fossil-based benzene—a process that is energy-intensive and emits nitrous oxide, a potent greenhouse gas.

The shift to bio-based caprolactam focuses on replacing this petrochemical route with microbial fermentation, enzymatic cascades, or biocatalytic transformation of renewable feedstocks. Through metabolic engineering and bioprocess integration, researchers aim to develop efficient, scalable routes to produce caprolactam from sugars, amino acids, or intermediates like cadaverine.

What Products Are Produced?

• Caprolactam – A lactam monomer used in
• Nylon-6 fibers and films
• Engineering plastics
• 3D printing filaments
• By-products – Glutamic acid, cadaverine, 6-aminocaproic acid (as intermediates or coproducts)

Pathways and Production Methods

1. Glucose to Caprolactam via Cadaverine

• Glucose → lysine → cadaverine (1,5-diaminopentane) → 6-aminocaproic acid → caprolactam
• Enzymes: Lysine decarboxylase, aminotransferases, lactam synthetase

2. Direct Biosynthesis Using Synthetic Pathways

• Engineered E. coli or Corynebacterium glutamicum to convert sugars into 6-aminocaproic acid, which is then cyclized to caprolactam
• Recent advances using non-natural enzymatic cascades

3. Whole-Cell Biocatalysis

• Cells engineered to express multi-enzyme systems that carry out all steps from sugar to caprolactam in a single process
• Benefits: in situ cofactor regeneration and simpler downstream processing

Catalysts and Key Tools Used

Microbial Hosts:

• E. coli, C. glutamicum, Pseudomonas putida, Bacillus subtilis

Key Enzymes:

• Lysine decarboxylase
• Diamine oxidase
• Cyclase or lactam synthetase (engineered or discovered enzymes)
• Transaminases and ketoacid reductases

Synthetic Biology Tools:

• CRISPR-Cas genome engineering
• Pathway modularization and balancing
• Directed evolution of lactam-forming enzymes
• Adaptive laboratory evolution for strain robustness

Case Study: Genomatica’s Bio-Caprolactam R&D Program

Highlights

• Developed a sugar-to-nylon intermediate platform
• Focused on fermentative production of cadaverine and conversion to caprolactam
• Collaborated with Aquafil to explore renewable nylon production

Timeline

• 2013 – First-generation bio-cadaverine pathway developed
• 2016 – Demonstrated pilot-scale 6-aminocaproic acid synthesis
• 2021 – Joint R&D with Aquafil on nylon-6 monomer
• 2024 – Patented synthetic route for enzymatic lactam formation

Global and Indian Startups Working in This Area

Global

• Genomatica (USA) – Bio-caprolactam and nylon intermediates
• CJ CheilJedang (Korea) – Bio-lysine and cadaverine pathways
• Evonik (Germany) – Bio-based C6 building blocks for polymers
• Aquafil (Italy) – Nylon-6 recycling and bio-caprolactam exploration

India

• Praj Industries – Exploring C6 diacid and diamine routes from sugars
• IIT Guwahati & IISc Bangalore – Cadaverine and aminocaproic acid via fermentation
• CSIR-IICT & ICT Mumbai – Enzymatic lactam synthesis from lysine analogs
• Godavari Biorefineries – C6 platform chemicals for nylon and fibers

Market and Demand

The global caprolactam market stood at USD 15.4 billion in 2023 and is expected to reach USD 20.7 billion by 2030, growing at a CAGR of ~4.5%. Bio-based caprolactam is projected to grow at ~10% CAGR, driven by sustainable textiles and green engineering plastics.

Major Use Segments:

• Nylon-6 fibers – Apparel, carpets, industrial yarns
• Automotive components – Light-weight and durable parts
• Consumer electronics – Housings and internal components
• 3D printing – Bio-nylon filaments
• Eco-label products – Sustainable textile certifications (e.g., OEKO-TEX, GRS)

Key Growth Drivers

• Demand for sustainable and bio-based nylons
• Rapid adoption of eco-textiles and circular fashion
• Stringent regulations on carbon footprint and nitrous oxide emissions
• Innovations in biocatalysis and metabolic engineering
• Interest from automotive and electronics sectors for green materials

Challenges to Address

• Low enzymatic activity for lactam formation
• Multi-step synthesis bottlenecks in engineered strains
• High purification costs and yield limitations
• Competition from recycled nylon-6 in sustainability claims
• In India: Need for pilot-scale validation and investment in biopolymer value chains

Progress Indicators

• 2012–2014 – Cadaverine production pathways published
• 2016 – Proof-of-concept 6-aminocaproic acid fermentation
• 2019 – Enzyme discovery for lactam synthesis
• 2022 – Pilot-scale studies on bio-caprolactam derivatives
• 2024 – Multiple patents on bio-caprolactam processes filed

Cadaverine fermentation: TRL 8–9 globally. 6-aminocaproic acid synthesis: TRL 6–7. Full microbial caprolactam biosynthesis: TRL 4–5 (proof-of-concept to pilot). In India: R&D active at TRL 3–6, with emerging pilot programs

Conclusion

The bio-based production of caprolactam is an essential innovation for making nylon-6 sustainable. By leveraging engineered microbial platforms and enzymatic routes, researchers are closing the loop on a critical petrochemical. Though technical hurdles remain, particularly around lactam cyclization, steady progress is being made.

With growing demand for green textiles, automotive components, and bio-engineered plastics, and India’s expanding bio-based chemicals infrastructure, caprolactam from renewable sources may soon power a cleaner, circular nylon economy.

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