ABSTRACT
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.
