Light-driven optimisation of high-value aromatic compound production in metabolically engineered cyanobacteria

The development of a circular, bio-based economy is a major challenge of this century. Photosynthesis-driven biomanufacturing offers a sustainable approach to biotechnological production and CO2 recycling, contributing to carbon neutrality. This study examines the effect of different light intensities on the metabolically engineered cyanobacterium Synechococcus elongatus PCC 7942 (2PE_aroK strain), which produces 2-phenylethanol (2-PE), a valuable aromatic compound used in food and cosmetics industries. The investigation was conducted in a flat-panel photobioreactor under various light conditions (0–500 μmol photons m2 s 1). We identified 150 μmol photons m2 s 1 as optimal, yielding 282 mg L 1 2-PE, with a productivity of 28.7 mg L 1 d 1 and 87 % light absorption efficiency. At lower light intensities, 45–50 % of carbon was allocated to 2-PE, decreasing to 28 % at higher intensity. The study highlights the metabolic interplay between photosynthesis, carbon utilisation, and target product formation, providing insights for optimised photosynthesis-based biomanufacturing.