Effects of lighting technologies on the physiology of a marine diatom, Cocconeis scutellum var. parva (Bacillariophyceae): 2. production of antioxidants and other bioactive compounds

Diatoms are microalgae showing a remarkable functional diversity, but their chemical composition is strongly influenced by environmental factors. Knowledge of benthic diatom physiology remains limited compared to planktonic taxa. Light and temperature are key environmental cues affecting biochemical pathways, suggesting that bioactive compound production may vary under different conditions. This study investigated the influence of four light spectra on the growth and secondary metabolite production of the benthic diatom Cocconeis scutellum var. parva. Led lamps demonstrated to be quite efficient in terms of biomass productivity, promoting a significantly higher biomass production with lower energy consumption. Extracts from cultures were characterized and evaluated for cytotoxicity on human cell lines, antioxidant activity, and radical scavenging capacity. Our results revealed marked differences in bioactivity depending on the light spectrum, with neon lamps and one LED system, rich in red light, promoting the highest biological activity. These findings demonstrate that optimizing light conditions is crucial for enhancing the quality of diatom-derived bioactive compounds. Spectral modulation under constant irradiance specifically altered antioxidant and anti-proliferative activities, highlighting the biotechnological potential of C. scutellum var. parva for medical, pharmaceutical, nutraceutical, cosmeceutical, and aquaculture applications.