Engineering Cyanobacteria for High-Yield Photosynthetic Isoprene Production With Long-Term Phenotypic Stability

Area of Science:

• Biotechnology
• Synthetic Biology
• Sustainable Chemistry

Background:

• The transition to a sustainable bioeconomy necessitates efficient methods for producing chemicals and fuels from CO2 using sunlight.
• Isoprene, a key industrial feedstock currently derived from crude oil, can potentially be produced by photosynthetic microorganisms.

Purpose of the Study:

• To develop novel strains of Synechocystis sp. PCC 6803 for high-level isoprene production.
• To enhance the genetic and metabolic stability, biosafety, and thermotolerance of engineered cyanobacteria for industrial applications.

Main Methods:

• Utilized diverse metabolic engineering strategies to modify Synechocystis sp. PCC 6803.
• Introduced the plant enzyme isoprene synthase into cyanobacteria for heterologous expression.
• Characterized engineered strains for growth, stability, and productivity.
• Conducted photosynthetic terpenoid production tests in photobioreactors under process-relevant conditions.

Main Results:

• Developed new cyanobacterial strains capable of significant isoprene production from CO2.
• Achieved the highest reported volumetric productivities for a terpenoid in cyanobacteria (148 mg L-1 day-1).
• Demonstrated improved genetic and metabolic stability, biosafety, and thermotolerance in engineered strains.

Conclusions:

• Metabolic engineering of Synechocystis sp. PCC 6803 enables efficient photosynthetic isoprene production.
• The developed strains and processes address key challenges for large-scale biotechnological hydrocarbon production.
• This work lays the foundation for stable, large-scale cyanobacterial hydrocarbon production without selection pressure.