Nitrogenase activity of the non-heterocystous cyanobacteriumPhormidium foveolarum

✍ Scribed by Hans Weisshaar; Peter Böger

• Book ID: 104770104
• Publisher: Springer
• Year: 1983
• Tongue: English
• Weight: 449 KB
• Volume: 136
• Category: Article
• ISSN: 0302-8933
• DOI: 10.1007/bf00425215

✦ Synopsis

Influence of light intensity and oxygen concentration on induction of nitrogenase activity were investigated. To fix nitrogen net photosynthetic oxygen evolution has to be about zero, using either low light intensity (~ 1 W/m 2) or higher light conditions together with an inhibitor of photosynthetic electron transport DCMU [3-(3,4-dichlorophenyl)-1,1-dimethylurea] present. Hydrogen evolution by nitrogenase is 2 to 3 times higher than ethylene formation. This is also evident in a cell-free nitrogenase assay. In intact cells of Phormidium foveolarum no uptake hydrogenase is present which again can be confirmed by a cell-free system. Apparently respiration, measured as CO2 evolution, is necessary for energy and reductant supply to nitrogenase. Furthermore, oxygen pressure is kept low to establish microaerobic conditions in the cell.