The Relationship between Nitrogenase Activity and Hydrogen Evolution in Rhodopseudomonas palustris

Abstract

Cells of Rhodopseudomonas palustris released a large amount of molecular hydrogen when illuminated anaerobically in the presence of certain organic compounds, as electron donors. This hydrogen formation, like nitrogenase activity, was dependent on light illumination. Both hydrogen evolution and nitrogenase activity were almost completely inhibited by addition of ammonium salts. The rate of hydrogen production was almost proportional to nitroogenase activity but no relationship was seen between hydrogen production and hydrogenase activity. In molybdenum starved cells, hydrogen evolution and nitrogenase activity decreased similarly and markedly. Nif~ mutant strains, which lack nitrogenase activity, were incapable of producing hydrogen. These results suggest that hydrogen production is clearly catalyzed by nitrogenase in this bacterium. When nitrogen gas or glutamate was used as an inducer for nitrogenase synthesis, lactate was the best substrate for hydrogen evolution among organic acids examined. The rate of hydrogen production with lactate was 40~50 cells (dry weight). © 1980, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.