Isoprene from Sugar

Isoprene (C5H8), a volatile hydrocarbon, is a crucial precursor for synthetic rubber, adhesives, and biofuels. Traditionally sourced from petroleum, isoprene is increasingly being produced via microbial fermentation of sugars, offering a greener, renewable alternative.

Microbial Isoprene Production: Process Overview

Isoprene is synthesized biologically using engineered microbes through either the methylerythritol 4-phosphate (MEP) or mevalonate (MVA) pathways:

• Feedstock Preparation: Sugars from corn, sugarcane, or lignocellulosic biomass serve as carbon sources. Lignocellulosic hydrolysates offer a cost-effective, non-food alternative.
• Biosynthesis:
• MEP Pathway: Utilized in bacteria like E. coli, converting pyruvate and G3P to IPP and DMAPP.
• MVA Pathway: Preferred in yeast (e.g., S. cerevisiae), converting acetyl-CoA to IPP/DMAPP.
• Isoprene Synthase (IspS) from plants converts DMAPP to isoprene.
• Fermentation: Conducted at 30–37°C (pH 6–7), with isoprene collected via gas stripping or condensation due to its volatility. Titers can reach up to 60 g/L in optimized systems.
• Metabolic Engineering Enhancements:
• Overexpression of Dxs, Dxr (MEP pathway enzymes)
• CRISPR/Cas9 knockouts to eliminate carbon sinks
• Use of Yarrowia lipolytica for broader substrate range
• Recovery & Purification: Off-gas systems capture isoprene with >99% purity.

Case Study: Amyris & Michelin Collaboration

ETC-bioisoprene-Amyris-Michelin-2023
Amyris engineered S. cerevisiae to produce 50 g/L isoprene from sugarcane syrup, with gas-stripping recovery. Strategic partnership with Michelin aims for a 50,000 t/year plant by 2026.

Timeline & Outcome:

• 2020: Proof-of-concept lab fermentation achieved ~20 g/L isoprene.
• 2021: Process intensified—titer increased to 35 g/L via pathway optimization.
• 2022: Demonstration plant built in Brazil; yield reached 50 g/L.
• 2023: Michelin partnership announced; engineering for 50,000 t/year scale-up underway.
• 2024–2025: Engineering design, permitting, and pilot sampling ongoing.
• 2026 (Projected): Start-up of commercial plant with global distribution potential.

Final Outcome:

Amyris is progressing from pilot validation to commercial deployment, proving industrial viability of bio-isoprene.

Global Innovators

• Amyris (USA): Commercial-scale isoprene from sugarcane, focus on tires/adhesives.
• Genomatica (USA): E. coli-based platform targeting <$1/kg production.
• Global Bioenergies (France): Produces isoprene from lignocellulosic sugars for jet fuels.

Indian Players with Potential

Though none currently specialize in bio-isoprene.

India’s bioeconomy benefits from 500+ million tons/year of agri-residues and DBT/BIRAC support.

Commercialization Outlook

Market Segments

• Synthetic Rubber & Tires – core demand sector
• Adhesives & Elastomers – industrial applications
• Biofuels & Jet Fuel Precursors – emerging high-value market

Cost & Efficiency

• Current Production Cost: $1.00–2.00/kg
• Target Cost: <$1/kg via consolidated bioprocessing & strain improvement
• Efficiency Advances:
• Dxs overexpression → +40% yield increase
• Y. lipolytica on lignocellulosic feed → 30% cost cut
• CRISPR-edited IspS → enhanced productivity

Growth Drivers

• Rising tire demand with sustainability mandates
• White-label demands for bio-based adhesives
• Aviation fuel alternative vectors

Defined Challenges & Price Comparison

• High Enzyme & Pathway Cost: Enzymes and engineered constructs account for 15–25% of OPEX → $0.15–0.50/kg
• Volatile Recovery: Isoprene’s low boiling point complicates containment and capture
• Pathway Inefficiency: Carbon losses to competing pathways lower yield by 10–20%
• Substrate Feedstock Cost: Sugarcane syrup ~$0.20/kg; lignocellulosic hydrolysate $0.10/kg but requires additional pretreatment ($0.05–0.10/kg)
• Scale-Up Risk: Pilot scale limited to <1,000 L; industrial scale must ensure consistent titer, rate, and yield

Progress Indicators

• 2020: Lab titer reaches 20 g/L using sugarcane syrup
• 2021: Titer improved to 35 g/L through pathway fine-tuning
• 2022: Demonstration plant delivers 50 g/L titer
• 2023: Michelin partnership secures scale-up project
• 2024–2025: Engineering and pilot construction underway
• 2026 (Projected): Commercial production launch

Technology Readiness Level: TRL 6–9 — ranging from pilot stage (Genomatica, Global Bioenergies) to full commercial deployment (Amyris).

Conclusion

Microbial isoprene from sugars is transitioning from pilot to commercial scale. Amyris demonstrates feasibility, while Genomatica and Global Bioenergies advance pathway optimization. In India, firms like Praj and Godavari can pivot into this sector, leveraging biomass and fermentation strengths. Bio-isoprene is set to revolutionize synthetic rubber and fuel sectors, aligning with global sustainability goals.

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