[Research progress and prospects of cyanobacterial cell factories for ethylene production]

Ethylene, a fundamental feedstock in the petrochemical industry, is conventionally produced via energy-intensive steam cracking of fossil fuels, a process associated with high energy consumption and carbon emissions. Constructing photosynthetic cyanobacterial cell factories for the direct, solar-driven conversion of CO₂ to ethylene offers a promising route for the green production of ethylene. This review systematically summarizes recent advances in this field, highlighting the core catalytic mechanism of the ethylene-forming enzyme (EFE), the screening and optimization of key genetic elements, metabolic engineering strategies (including gene copy number amplification, precursor supply enhancement, rewiring of carbon flux, and alleviation of by-product inhibition), and the optimization of cultivation processes. Furthermore, we identify the key challenges currently impeding cyanobacterial production of ethylene, such as low yields and efficiencies, insufficient genetic stability, and bottlenecks in large-scale cultivation. Finally, we outline future development directions-advancing synthetic biology tools, enabling precise regulation of metabolic networks, designing efficient photobioreactors, and integrating industrial technologies, with the aim of providing a theoretical foundation for establishing robust and high-performance cyanobacterial cell factories for ethylene production and facilitating their practical application.