Shifts in the intracellular ATP pools of immobilisedNostoc cells (Cyanobacteria) induced by water stress

Summary Immobilised, desiccated cells ofNostoc commune UTEX 584 have the capacity to increase the size of their extractable intracellular ATP pool upon rewetting. The time taken to recover the pool size depends on the conditions of storage at a particular water potential and the duration of storage. Under the conditions employed, the rewetting of cells induced an increase in ATP pool size at the expense of photophosphorylation or electron transport (oxidative) phosphorylation. The rise in the ATP pool size was instantaneous and was shown to be due to ATP synthesis. This increase did not occur when cells were rewetted in the presence of sodium azide (10 mmol/l), while a partial inhibition was observed with CCCP (carbonyl cyanidem-chlorophenylhydrazone; 2 mol/l). For cells dried at more extreme water potentials, the lag ofc 48 h observed before the ATP pool reached control values is of similar duration to that observed in the recovery of nitrogenase upon rewetting. Chloramphenicol (10 mol/l) stimulated significantly the upshift in the size of the ATP pool ofNostoc cells upon rewetting, yet inhibited completely the rise in nitrogenase activity.