C1 photochemotrophy - rethinking one-carbon metabolism in phototrophs.

Excessive CO₂ emissions, caused by an imbalance between carbon oxidation and reduction, drive climate change. To address this, we propose photochemotrophic metabolism as an alternative to both canonical photosynthesis and synthetic one-carbon (C1) metabolism in heterotrophs. In photochemotrophy, naturally phototrophic microorganisms such as cyanobacteria serve as the chassis to assimilate chemically reduced and soluble C1 compounds such as formate or methanol by using carbon fixation cycles that are more efficient than the native Calvin cycle. Key potential advantages of photochemotrophy include enhanced carbon fixation efficiency, utilization of storable carbon compounds, retention of energy from the original CO₂ reduction, and decoupling of carbon delivery and electron source. This proposed strategy positions photochemotrophic cyanobacteria as a promising tool for advancing the bioeconomy.