Sustained photobiological hydrogen production by Chlorella vulgaris without nutrient starvation

This article describes the ability of the Chlorella vulgaris BEIJ strain G-120 to produce hydrogen (H-2) via both direct and indirect pathways without the use of nutrient starvation. Photobiological H-2 production reached a maximum rate of 12 mL H-2 L(-1 )h(-1), corresponding to a light conversion efficiency (light to H-2) of 7.7% (average 3.2%, over the 8-day period) of PAR, (photosynthetically active irradiance). Cells presented a maximum in vivo hydrogenase activity of 25.5 +/- 0.2 nmoles H-2 mu gChl(-1) h(-1) and the calculated in vitro hydrogenase activity was 830 +/- 61 nmoles H-2 mu gChl(-1) h(-1). The strain is able to grow either heterotrophically or photo autotrophically. The total output of 896 mL of H-2 was attained for illuminated culture and 405 mL for dark cultures. The average H-2 production rate was 4.98 mL L-1 h(-1) for the illuminated culture and 2.08 mL L-1 h(-)(1) for the one maintained in the dark. (C) 2020 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.