Photoautotrophic hydrogen production by nitrogen-deprived Chlamydomonas reinhardtii cultures

In this study we have demonstrated the possibility of phototrophic hydrogen production in C. reinhardtii under N-deprived conditions. When tested under air + CO2, and Ar + CO2 N-deprived C. reinhardtii demonstrated decrease in PSII activity mainly due to over reduction of PQ in addition no ascorbate accumulation was observed in cells. Under air + CO2 atmosphere cells accumulated excessive amounts of starch. When incubated under Ar + CO2 atmosphere cells accumulated starch as nitrogen replete cultures and no hydrogen production was observed. Hydrogen production (86 ml H-2 per one 1 of culture) occurred under Ar + CO2 atmosphere when particular two-step illumination protocol was implicated. In oxygen producing and early oxygen consuming stage cells were illuminated under light intensity 169 mu E M-2 s(-1). When light was switched to 30 mu E M-2 s(-1), cultures quickly respired all oxygen and transient to anaerobic conditions with subsequent hydrogen production 2 h later. Actual quantum yield of C. reinhardtii cultures was measured in photo-bioreactor and maximal quantum efficiency of PSII of dark adapted cells together with JIP test were studied. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.