adjusted light and dark cycles can optimize photosynthetic efficiency in algae growing in photobioreactors光明与黑暗周期调整可以在生物反应器优化藻类光合效率增长.pdfVIP

Adjusted Light and Dark Cycles Can Optimize Photosynthetic Efficiency in Algae Growing in Photobioreactors 1 2 2 1 2 Eleonora Sforza , Diana Simionato , Giorgio Mario Giacometti , Alberto Bertucco , Tomas Morosinotto * ` ` 1 Dipartimento di Ingegneria Industriale DII, Universita di Padova, Padova, Italy, 2 Dipartimento di Biologia, Universita di Padova, Padova, Italy Abstract Biofuels from algae are highly interesting as renewable energy sources to replace, at least partially, fossil fuels, but great research efforts are still needed to optimize growth parameters to develop competitive large-scale cultivation systems. One factor with a seminal influence on productivity is light availability. Light energy fully supports algal growth, but it leads to oxidative stress if illumination is in excess. In this work, the influence of light intensity on the growth and lipid productivity of Nannochloropsis salina was investigated in a flat-bed photobioreactor designed to minimize cells self-shading. The influence of various light intensities was studied with both continuous illumination and alternation of light and dark cycles at various frequencies, which mimic illumination variations in a photobioreactor due to mixing. Results show that Nannochloropsis can efficiently exploit even very intense light, provided that dark cycles occur to allow for re-oxidation of the electron transporters of the photosynthetic apparatus. If alternation of light and dark is not optimal, algae undergo radiation damage and photosynthetic productivity is greatly reduced. Our results demons