초록
Previously, we found that marine Chlorella pyrenoidosa strain IOAC707S could generate hydrogen (H<SUB>2</SUB>) under nitrogen deprivation in seawater medium, without dark incubation, N<SUB>2</SUB> flushing or addition of protonophore. In this work, the H<SUB>2</SUB> yield of C. pyrenoidosa was enhanced, and the mechanism of H<SUB>2</SUB> photoproduction was investigated. It was found that C. pyrenoidosa could produce H<SUB>2</SUB> under hypoxic conditions, which indicated the hydrogenase of C.pyrenoidosa could tolerate a low concentration of O<SUB>2</SUB>. Nitrogen deprivation could lower the efficiency of photosyntem (PS) II photochemical activity and PSII oxygenic activities, which were favorable for rapid establishment of anoxia and efficient H<SUB>2</SUB> photoproduction, and thus significantly enhance H<SUB>2</SUB> photoproduction of C. pyrenoidosa. Pre-culture in nitrogen-deprived medium could further increase the H<SUB>2</SUB> yield of C. pyrenoidosa, for its more severe inhibition of the oxygen-evolving complex, electron transport and photochemical efficiency of PSII, and PSII oxygenic activities, which facilitated the establishment of anaerobiosis and activation of hydrogenase.