Pigment-targeted light wavelength and intensity promotes efficient photoautotrophic growth of Cyanobacteria

Abstract

A consensus is lacking whether monochromatic rather than broad-spectrum illumination is more efficient for photosynthetic microbe production platforms. Light wavelength and intensity were tuned to pigment composition for growth of the Cyanobacterium Synechocystis PCC 6803. Phycocyanin (PC)-targeting LEDs (620nm) provided more than 6times the peak efficiency of white LEDs, with peak efficiency growth rates of 0.063h−1 at 81μEm−2s−1 and 0.039h−1 at 126μEm−2s−1 for red and white LEDs, respectively. Chlorophyll a (Chl a)-targeting LEDs (680- and 440-nm) performed poorly. Indeed, 10 times greater mass abundance was observed for PC than Chl a. PC levels did not change while Chl a levels decreased when Synechocystis transitioned from white light at 50μEm−2s−1 to 250μEm−2s−1 with 620nm, 680nm, or white LEDs. This work demonstrates that light wavelengths and intensity need to be optimized for each strain.