Photosynthetic performance of two Nannochloropsis spp. under different filtered light spectra

The integration of spectrally selective photovoltaic filters together with microalgae cultivation systems have been previously shown to improve both production efficiency and economics. This means that filtered irradiance incident upon the culture is a portion of the entire solar spectrum. In order to test the viability and optimize such integrated systems, in depth growth and photosynthesis studies of microalgae in such conditions are required. In this applied study, we investigated the impact of spectrally limited light and concomitant reduction in light irradiance on the photosynthetic efficiency of two acclimated Nannochloropsis spp. (MUR 266 & MUR 267) through chlorophyll a fluorescence and oxygen evolution based measurements under laboratory controlled conditions. Results indicated that (i) no similarities were found between both Nannochloropsis spp. in regards of their biomass productivity and photosynthetic performance, (ii) blue light acclimated cultures had remarkably higher concentration of chlorophyll a and accessory pigments over biomass due to the lower irradiance, (iii) when photosynthesis was measured on the basis of chlorophyll a fluorescence (based on number of photons absorbed per chlorophyll) and oxygen evolution (based on chlorophyll a content), pink and white light was most efficient for MUR 266 and MUR 267 respectively. The results of this study clearly indicate that by manipulating the spectral distribution of incident light, photosynthetic efficiency of microalgae can be regulated to optimum levels. The allocation of light spectra (i.e. blue) most efficient for the growth and photosynthesis of the microalgae would allow for the generation of up to 151 W m^− 2 of electrical energy from the remaining unused spectra of sunlight using highly efficient crystalline silicone solar cells.