Thin cell layer cultures of Chlamydomonas reinhardtii L159I-N230Y, pgrl1 and pgr5 mutants perform enhanced hydrogen production at sunlight intensity

Photobiological hydrogen (H2) production is a promising renewable energy source. HydA hydrogenases of green algae are efficient but O2-sensitive and compete for electrons with CO2-fixation. Recently, we established photoautotrophic H2 system based on anaerobic induction, where the Calvin-Benson cycle inactive O2 scavenged by an absorbent. Here, employed thin layer cultures, resulting in three-fold increase relative to bulk CC-124 cultures (50 µg chlorophyll/ml, 350 µmol photons m?2 s?1). Productivity was maintained when increasing light intensity 1000 m-2s?1 cell density 150 chlorophyll/ml. Remarkably, L159I-N230Y photosystem II mutant pgrl1 I cyclic electron transport produced 50% more than CC-124, while pgr5 generated 250% (1.2 ml H2/ml culture six days). The photosynthetic apparatus its vitro activity remained remarkably stable.