Effect of the temperature, pH and irradiance on the photosynthetic activity by Scenedesmus obtusiusculus under nitrogen replete and deplete conditions

This paper evaluates the effect of the irradiance, pH and temperature on the photosynthetic activity (PA) of Scenedesmus obtusiusculus under N-replete and N-deplete conditions through oxygen measurements. The highest PA values were 160 mg(O2) g(b) (1) h (1) at 620 mu mol m (2) s (1), 35 degrees C and pH of 8 under N-replete conditions and 3.3 mg(O2) g(b) (1) h (1) at 100 mu mol m (2) s (1), 28.5 degrees C and pH of 5.5 for N-deplete conditions. Those operation conditions were tested in a flat-panel photobioreactor. The biomass productivity was 0.97 g(b) L (1) d (1) under N-replete conditions with a photosynthetic efficiency (PE) of 4.4% yielding 0.85 g(b) mol(photon)(1). Similar biomass productivity was obtained under N-deplete condition; and the lipid productivity was 0.34 g(L) L (1) d (1) with a PE of 7.8% yielding 0.39 g(L) mol(photon)(1). The apparent activation and deactivation energies were 16.1 and 30 kcal mol (1), and 11.9 and 15.3 kcal mol (1), for N-replete and N-deplete conditions, respectively. (C) 2015 Elsevier Ltd. All rights reserved.