Cell Age Optimization for Hydrogen Production Induced by Sulfur Deprivation Using a Green Alga Chlamydomonas reinhardtii UTEX 90

Under sulfur deprived conditions, PS Ⅱ and photosynthetic O₂ evolution by Chlamydomonas reinhardtii UTEX 90 are inactivated, resulting in shift from aerobic to anaerobic condition. This is followed by hydrogen production catalyzed by hydrogenase. We hypothesized that the photosynthetic capacity and the accumulation of endogenous substrates such as starch for hydrogen production might be different according to cell age. Accordingly, we investigated (a) the relationships between hydrogen production, induction time of sulfur deprivation, increase of chlorophyll after sulfur deprivation, and residual PS Ⅱ activity, and (b) the effect of initial cell density upon sulfur deprivation.