Influence of spectral light quality on the pigment concentrations and biomass productivity of Arthrospira platensis

The species in the Arthrospira genus are cultured at a large scale throughout the world primarily for food supplements for human and animal diets. These species are valued for the rich composition of their biomass, which contains minerals, antioxidants, proteins and essential amino acids. This biomass can also be used for high-value product extraction, for example, the pigments chlorophyll a, beta-carotene and phycocyanin as well as essential fatty acids. The use of LEDs is a solution for optimizing the productivity and biochemical composition of biomass produced by these microalgae. In this study, an innovative strategy for using LEDs was evaluated for Arthrospira platensis cultivation to increase its biomass productivity and high-value pigments (chlorophyll a, total carotenoids and phycocyanin). Microalgae suspensions were cultured in 250 mL Erlenmeyer flasks containing 120 mL of culture (George-modified Zarrouk's medium, pH 8.90) at 32 +/- 1 degrees C with constant stirring and an initial biomass concentration of 0.03 g L-1. The biomass weights from ten lighting conditions consisting of blue and red LEDs of different compositions were evaluated in relation to the algal productivity and the chlorophyll a, total carotenoid and phycocyanin contents. The best results were obtained using LEDs that had a 70% red and 30% blue composition and a light intensity of 100 mu Em(-2) s(-1), leading to an average biomass productivity of 0.148 g L(-1)d(-1) and average concentrations of 21.35 mu gmL(-1), 5.45 mu gmL(-1) and 167.98 mu gmL(-1) of chlorophyll a, carotenoids and phycocyanin, respectively, in the given culture volume.