SALT-INDUCED PHOTOSYSTEM-I CYCLIC ELECTRON-TRANSFER RESTORES GROWTH ON LOW INORGANIC CARBON IN A TYPE-1 NAD(P)H DEHYDROGENASE DEFICIENT MUTANT OF SYNECHOCYSTIS PCC6803

The cyanobacterium Synechocystis PCC6803 induces a photosystem I cycli c electron transfer route independent of type 1 NAD(P)H dehydrogenase. The capacity to tolerate raised salinity conditions was shown to oper ate in a mutant lacking functional type 1 NAD(P)H dehydrogenase. The m utant showed salt-induced enhancement of photosystem I cyclic electron transfer and respiratory capacities. Moreover, this salt-adapted ener getic state also restored the capacity of the mutant to grow under ino rganic carbon limitation. Uptake of the latter in these conditions bec ame almost as efficient as in the wild-type. The acquired energetic ca pacities, in contrast, did not allow restoration of photoheterotrophic growth in the type I NAD(P)H dehydrogenase mutant. (C) 1998 Federatio n of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.