Systematic Insights into Cost-Efficient Biomass and Pigment Production of Limnospira maxima (spirulina) under Varied LED Spectra and Intensities

Finding an optimal artificial light source for photoautotrophic microalgae cultivation is a complex task. This study provides missing data for Limnospira ( Arthrospira ) maxima cultivation and key aspects for evaluating this issue. Rigorous experimental datasets were analyzed to clarify the relationship between illumination (LEDs) characteristics (intensity and spectral composition) and biomass/pigments production, considering energy costs in the technologically relevant light-limited region of the photosynthesis-irradiance curve (up to 550 µmol/m²/s). Using the same light spectra (cool white), higher light intensities consistently increased biomass productivity, with a maximum of 0.97 g/L/day at 550 µmol/m²/s. However, the lowest energy costs per unit of biomass and pigments were achieved under low light intensity of 100 µmol/m²/s (0.57 kWh/g of biomass, 2.45 kWh/g of phycocyanin, 51.4 kWh/g of carotenoids, and 15.4 kWh/g of chlorophyll a ). When spectral composition was varied at constant light intensity of 50 µmol/m²/s, the highest productivity and lowest energy costs were observed under daylight white and warm white light, followed by red. Surprisingly, pigment content remained relatively stable across all spectra. These findings provide practical guidance for optimizing L. maxima cultivation by balancing productivity and energy efficiency.