Influence of spectral intensity and quality of LED lighting on photoacclimation, carbon allocation and high-value pigments in microalgae.

Tailoring spectral quality during microalgal cultivation can provide a means to increase productivity and enhance biomass composition for downstream biorefinery. Five microalgae strains from three distinct lineages were cultivated under varying spectral intensities and qualities to establish their effects on pigments and carbon allocation. Light intensity significantly impacted pigment yields and carbon allocation in all strains, while the effects of spectral quality were mostly species-specific. High light conditions induced chlorophyll photoacclimation and resulted in an increase in xanthophyll cycle pigments in three of the five strains. High-intensity blue LEDs increased zeaxanthin tenfold in Rhodella sp. APOT_15 relative to medium or low light conditions. White light however was optimal for phycobiliprotein content (11.2 mg mL-1) for all tested light intensities in this strain. The highest xanthophyll pigment yields for the Chlorophyceae were associated with medium-intensity blue and green lights for Brachiomonas submarina APSW_11 (5.6 mg g-1 lutein and 2.0 mg g-1 zeaxanthin) and Kirchneriella aperta DMGFW_21 (1.5 mg g-1 lutein and 1 mg g-1 zeaxanthin), respectively. The highest fucoxanthin content in both Heterokontophyceae strains (2.0 mg g-1) was associated with medium and high white light for Stauroneis sp. LACW_24 and Phaeothamnion sp. LACW_34, respectively. This research provides insights into the application of LEDs to influence microalgal physiology, highlighting the roles of low light on lipid metabolism in Rhodella sp. APOT_15, of blue and green lights for carotenogenesis in Chlorophyceae and red light-induced photoacclimation in diatoms.