Programmable microalgae: Engineering sense-decide-adapt systems for dynamic environmental performance.

Microalgal strains are engineered and benchmarked under fixed conditions, yet industrial cultures experience light, temperature, CO₂, salinity and nutrient regimes that shift from seconds to seasons. Programmable microalgae, cells that sense environmental change, integrate signals and adjust their physiology (Sense-Decide-Adapt, SDA), could close this gap. Native nutrient-sensing, photoprotective, carbon-concentrating and osmotic programs already approximate SDA architectures, and genome editing, biosensors and single-cell screening make them tractable to rewire, although direct evidence that altering response dynamics raises productivity remains sparse. Here, we introduce the Environmental Performance Envelope (EPE), a framework defining the region of environmental space in which a strain retains a defined fraction of its reference productivity under realistic trajectories. The EPE turns a design question into an experiment: does engineering expand the operating space or merely relocate the optimum? A staged roadmap, including CO₂-fluctuation trials and evolutionary stability testing, shifts engineering targets from static traits to response kinetics, recovery, heterogeneity and stability, and couples cellular control to bioprocess design, pointing toward more robust algal biomanufacturing. Because environmental variability constrains any living system deployed outside the laboratory, the same logic may extend to other microbial cell factories, crops and engineered organisms.