Microbial Conversion of Biomass to Itaconic Acid

Introduction

Itaconic acid (IA) is a promising bio-based platform chemical used in the production of biodegradable plastics, resins, adhesives, coatings, and superabsorbent polymers. Traditionally derived via fermentation, itaconic acid has been identified by the U.S. Department of Energy as one of the top 12 value-added chemicals from biomass.

The microbial conversion of biomass to itaconic acid leverages engineered microbes—primarily fungi like Aspergillus terreus or bacteria like Ustilago maydis—to convert renewable carbohydrates or lignocellulosic hydrolysates into IA through a decarboxylation of cis-aconitate, a TCA cycle intermediate. The approach combines strain engineering, pathway optimization, and bioreactor process control to produce itaconic acid efficiently from waste biomass, aligning with the principles of the circular bioeconomy.

What Products Are Produced?

• Itaconic acid – Bio-based unsaturated dicarboxylic acid
• Polyitaconic acid – Used in bio-based plastics and dispersants
• Itaconates and derivatives – Platform molecules for biopolymers, coatings, and sealants

Pathways and Production Methods

1. Native Fungal Fermentation (e.g., Aspergillus terreus)

• Glucose or starch converted via glycolysis and TCA cycle
• Citrate → cis-aconitate → Itaconate (via cadA, cis-aconitate decarboxylase)
• High IA yields under low-pH, nitrogen-limited conditions

2. Engineered Microbial Systems

• Ustilago maydis, Escherichia coli, Yarrowia lipolytica engineered to produce IA
• Enhanced carbon flux through the TCA cycle and expression of cadA
• Tolerant to lignocellulosic hydrolysates, glycerol, and agro-waste sugars

3. Lignocellulosic Biomass Conversion

• Biomass (e.g., corn stover, bagasse) hydrolyzed into fermentable sugars
• Pretreatment: dilute acid, steam explosion
• Fermentation with IA-producing microbes in fed-batch or two-stage reactors

Catalysts and Key Tools Used

Microbial Hosts:

• Aspergillus terreus – Industrial standard for IA production
• Ustilago maydis – Robust, engineered for sugar and acid tolerance
• E. coli, Corynebacterium glutamicum – Synthetic IA pathways
• Yarrowia lipolytica – Tolerant to oils and complex substrates

Key Enzymes:

• CadA (cis-aconitate decarboxylase) – Key IA biosynthesis enzyme
• Aconitase (ACN) – Converts citrate to cis-aconitate
• Transporters – For secretion of IA and resistance to inhibition

Fermentation Technologies:

• Low-pH aerobic fermenters
• Cell-recycle systems to increase productivity
• Use of waste glycerol, molasses, and lignocellulose as feedstocks

Case Study: Itaconix (UK/USA) – Commercial Production of Bio-Based Itaconic Acid Polymers

Highlights

• Developed proprietary bio-based polymer platform from IA
• Uses fermentative IA as feedstock for detergents, coatings, superabsorbents
• Partnered with chemical companies like Nouryon and Croda
• Focused on replacing petrochemical acrylics with sustainable IA polymers

Timeline

• 2012 – Spinout from University of Portsmouth
• 2016 – Commercial IA polymer sales in home care sector
• 2019 – Expanded product line into cosmetics and coatings
• 2023 – Entered large-scale partnerships with US manufacturers

Global and Indian Startups Working in This Area

Global

• Itaconix (UK/USA) – Bio-based polymer ingredients from itaconic acid
• DSM (Netherlands) – Pilot-scale IA from engineered yeast
• BASF – Evaluation of IA as green alternative in coatings
• Novozymes – R&D on enzymes for IA-producing pathways

India

• Godavari Biorefineries (Maharashtra) – Exploring IA from sugar-based feedstocks
• CSIR-IIP & CSIR-IICT – Lignocellulosic to IA pathway development
• IIT Kharagpur, ICT Mumbai – Pilot studies on IA fermentation from bagasse
• Early-stage biotech incubatees under BIRAC and DBT for IA platform research

Market and Demand

The global itaconic acid market is expected to grow from USD 100 million in 2023 to USD 230 million by 2030, at a CAGR of ~12%, driven by growing demand in biodegradable plastics, green coatings, and home care formulations.

Major End-Use Segments:

• Bioplastics and polyitaconates
• Detergents and cleaning agents
• Adhesives and paints
• Personal care and cosmetics
• Superabsorbent polymers

Key Growth Drivers

• Rising shift toward bio-based and biodegradable materials
• Itaconic acid as a drop-in substitute for petrochemical acrylics
• Valorization of lignocellulosic and agricultural waste
• Strong interest in low-pH fermentations that reduce contamination
• CO₂-neutral production process with circular feedstock integration

Challenges to Address

• Product inhibition at high IA concentrations (feedback on enzymes)
• High oxygen demand and low yield in native fungal fermentation
• Scale-up of low-pH fermentation with foam and viscosity issues
• Downstream purification costs for food/pharma-grade IA
• Lack of widespread industrial deployment outside a few players

Progress Indicators

• 2005 – IA identified as top bio-based building block
• 2012 – Itaconix begins pilot-scale IA polymer production
• 2018 – Engineered E. coli and Ustilago strains hit >70 g/L IA titers
• 2022 – Indian studies on bagasse and stover-to-IA fermentation intensify
• 2024 – Bio-IA integrated into India’s green adhesives and detergent R&D

Biomass-to-itaconic acid fermentation is at TRL 8–9 globally (commercial production) and TRL 5–6 in India, with pilot-scale research underway using domestic agro-waste.

Conclusion

The microbial conversion of biomass to itaconic acid stands as a vital innovation in building a green chemicals industry. With applications across sustainable plastics, detergents, and packaging, IA offers a robust replacement to petrochemical acrylics. By integrating renewable feedstocks, engineered microbes, and scalable fermentations, this route aligns with India’s goals for a cleaner, circular, and self-reliant bioeconomy.

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