Effect of different light spectra on the growth and productivity of acclimated Nannochloropsis sp. (Eustigmatophyceae)

Abstract

There is a great need to further develop new technologies in the field of microalgal cultivation system. The integration of selectively wavelength-permeable photovoltaic cells together with microalgae cultivation systems to improve economics has been previously proposed. With no light supplementation, this means that filtered irradiance incident upon the culture is a portion of the full solar irradiance. Under laboratory controlled conditions using halogen lamps, the impact of spectrally limited light and concomitant reduction in light irradiance on the growth, biochemical composition and light use efficiency of acclimated Nannochloropsis sp. (MUR266) was studied. Pink light yielded the highest specific growth rate for Nannochloropsis sp. while the biomass productivity per photons and energy supplied were highest under blue light. The highest chlorophyll a cellular content of this alga was under blue and blue-green lights while lipid content was found to be significantly higher under blue light. Nannochloropsis sp. grown under dark (zero light) and green light (510–600nm) showed no net growth. The most efficient light to biomass conversion for Nannochloropsis sp. was found to be between 400 and 525nm (blue light). This indicates that targeting specific spectral components of the photosynthetic active radiation (PAR) such as the blue region can increase the biomass productivity and provide a platform for converting the remaining unused portions of the solar spectrum into electricity.