REVERSIBLE HYDROGENASE ACTIVITY OF GLOEOCAPSA-ALPICOLA IN CONTINUOUS-CULTURE

The unicellular non-N-2-fixing cyanobacterium Gloeocapsa alpicola stra in Fitzgerald 1051 was grown in continuous culture with nitrate as nit rogen source. Hydrogenase activity (measured in methyl viologen-depend ent H-2 evolution tests) was higher in cultures limited by light or ni trate and did not depend on the presence of oxygen. Development of hyd rogenase activity involved de novo protein synthesis. Both light-limit ed and nitrate-limited cells evolved H-2 in the dark due to fermentati on of stored glycogen. Nitrogen-limited, but not light-limited G. alpi cola consumed Ha in the light-dependent reaction. Addition of CO2 or N O3- enhanced H-2 uptake rate. (C) 1998 Federation of European Microbio logical Societies. Published by Elsevier Science B.V. All rights reser ved.