LAUSR

Light effect on cultures of microalgae has been studied mainly on single species cultures. Cyanobacteria have photosynthetic pigments that can capture photons of wavelengths not available to chlorophylls. A native Louisiana microalgae (Chlorella vulgaris) and cyanobacteria (Leptolyngbya sp.) co‐culture was used to study the effects of light quality (blue–467 nm, green–522 nm, red–640 nm and white–narrow peak at 450 nm and a broad range with a peak at 550 nm) at two irradiance levels (80 and 400 μmol m−2 s−1) on the growth, species composition, biomass productivity, lipid content and chlorophyll‐a production. The co‐culture shifted from a microalgae dominant culture to a cyanobacteria culture at 80 μmol m−2 s−1. The highest growth for the cyanobacteria was observed at 80 μmol μmol m−2 s−1 and for the microalgae at 400 μmol m−2 s−1. Red light at 400 μmol m−2 s−1 had the highest growth rate (0.41 d−1), biomass (913 mg L−1) and biomass productivity (95 mg L−1 d−1). Lipid content was similar between all light colors. Green light had the highest chlorophyll‐a content (1649 μg/L). These results can be used to control the species composition of mixed cultures while maintaining their productivity.