External Factors Influencing Light-Induced Hydrogen Evolution by the Blue-Green Alga, Nostoc Muscorum

Abstract

This study was conducted to determine some physiological conditions which influence light-induced hydrogen evolution by intact cells of the blue-green alga Nostoc muscorum. This activity was found to be dependent on the age of the culture, cultivation temperature, ageing of the cells, and on gassing the cultures with nitrogen or air. Nitrogenase is particularly active after cultivation at 22 °C but not at 32 °C although growth is about the same. The molar ratio of acetylene reduction to hydrogen evolution – both gas exchanges obviously catalyzed by nitrogenase - is also dependent on age and temperature of the culture. A hydrogen-consuming („uptake‟) hydrogenase activity is present and affected by prolonged microaerobic, but not by aerobic growth conditions, and stimulated by light. External factors during growth apparently influence differently the activities of nitrogenase and uptake hydrogenase. Consequently – besides the electron donor supply – net light-induced hydrogen evolution by intact cells is dependent on these two variable activities. © 1979, Walter de Gruyter. All rights reserved.