Fermentation of Biomass to Methacrylic Acid

Introduction

Methacrylic acid (MAA) is a crucial monomer in the production of polymethyl methacrylate (PMMA), also known as acrylic glass, used in automotive parts, paints, coatings, and medical devices. Traditionally, MAA is derived from acetone, hydrogen cyanide, and isobutylene—all fossil-based and energy-intensive processes that emit greenhouse gases.

To meet the demand for greener polymers, researchers are developing bio-based production of methacrylic acid using fermentation of renewable biomass such as sugars, glycerol, and agricultural residues. Through synthetic biology and metabolic engineering, microbes can convert biomass into isobutyric acid or itaconic acid, which can then be chemically or enzymatically transformed into MAA. This hybrid bio-chemical approach promises reduced emissions and fossil independence.

What Products Are Produced?

• Methacrylic acid (MAA) – Bio-based version
• Applications:
• Polymethyl methacrylate (PMMA) – transparent plastics
• Paints, adhesives, coatings, inks
• Medical devices, lenses, and resins
• Impact modifiers in PVC

Pathways and Production Methods

1. Isobutyric Acid Route

• Glucose → Isobutanol via keto-acid pathway → Isobutyric acid → MAA
• Final conversion via oxidative dehydrogenation

2. Itaconic Acid Route

• Glucose → Itaconic acid via Aspergillus terreus → MAA
• Decarboxylation of itaconic acid to MAA using decarboxylase enzymes or catalytic methods

3. Citramalate Pathway

• Glucose → Citramalate → Methacrylic acid via enzymatic and thermal decarboxylation
• Engineered E. coli expressing citramalate synthase

4. Hybrid Routes

• Bio-fermentation for intermediates (e.g., itaconate, mesaconate) + chemical upgrading
• Enables integration into existing polymer infrastructure

Catalysts and Key Tools Used

Microbial Hosts:

• E. coli, Corynebacterium glutamicum – for isobutyric and citramalate production
• Aspergillus terreus – itaconic acid fermentation
• Engineered Bacillus subtilis and Pseudomonas spp.

Key Enzymes:

• Citramalate synthase
• Isobutyrate dehydrogenase
• Itaconate decarboxylase

Tools:

• CRISPR-based strain optimization
• High-cell-density fermentation
• Chemical catalysis: oxidative dehydrogenation (Pd/C, Cu-Zn)
• Two-step biocatalysis and separation systems

Case Study: Lucite International’s Bio-Methacrylic Acid Initiative

Highlights

• Partnered with Genomatica to develop a fermentation-based MAA route
• Targeted isobutyric acid intermediate from sugars
• Demonstrated 50%+ GHG reduction compared to fossil MAA

Timeline

• 2013 – Research collaboration initiated
• 2017 – Successful lab-scale fermentation of isobutyric acid
• 2020 – Tech transfer and pilot testing in the UK
• 2023 – Demonstrated drop-in compatibility with PMMA infrastructure

Global and Indian Startups Working in This Area

Global

• Genomatica (USA) – Isobutyric acid platform for MAA
• Itaconix (UK/USA) – Fermentation of itaconic acid
• Lucite International (UK) – MAA via hybrid routes
• DSM – Working on green monomer platforms

India

• IIT Guwahati & NCL Pune – Enzymatic conversion of itaconic acid
• IIT Delhi – Citramalate biosynthesis optimization
• CSIR-IMTECH – Genetic tools for E. coli fermentation to itaconate
• Startups under BIRAC – Focus on lignocellulosic feedstocks to organic acids

Market and Demand

The global methacrylic acid market was valued at USD 9.4 billion in 2023, expected to reach USD 13.8 billion by 2030, with a CAGR of ~5.6%. The bio-based MAA segment, still emerging, is anticipated to grow at CAGR > 10%, driven by eco-friendly plastics and green coatings.

Major Use Segments:

• Transparent plastics (PMMA) – automotive, lighting, signage
• Coatings and adhesives
• Medical polymers and lenses
• Functional resins in electronics and construction

Key Growth Drivers

• Regulatory pressure on fossil-derived acrylates
• Growing demand for bioplastics and biodegradable coatings
• Potential for drop-in replacement in existing PMMA infrastructure
• Circular economy push from automotive and electronics industries
• Integration with sugar and itaconic acid supply chains

Challenges to Address

• Low titers and productivity in itaconate fermentation
• Toxicity of MAA to microbial hosts
• Downstream purification of MAA from fermentation broth
• In India: Need for demo-scale facilities for organic acid upgrading

Progress Indicators

• 2010–2015 – MAA fermentation proof-of-concepts (isobutyric, itaconate)
• 2018 – Pilot-scale itaconic acid to MAA achieved
• 2020–2023 – Enzymatic decarboxylation and bio-upgrading developed
• 2024 – Indian labs report yields >40 g/L of itaconate with engineered A. terreus

Isobutyric acid to MAA: TRL 7–8. Itaconic acid to MAA: TRL 6–7. In India: TRL 4–6, with active government and academic research

Conclusion

The fermentation of biomass to methacrylic acid represents a sustainable route to an essential monomer, reducing environmental impact and enabling fossil-free PMMA and coatings. As enzymatic decarboxylation and hybrid bio-chemical platforms mature, bio-MAA is moving closer to commercial deployment.

India’s strength in organic acid fermentation, combined with sugar surplus and research leadership, can catalyze the development of bio-MAA as a strategic monomer for the country’s polymer and specialty chemicals industry.

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