In vivo Na-23 nuclear magnetic resonance study of maintenance of a sodium gradient in the ruminal bacterium Fibrobacter succinogenes S85

Sodium gradients (Delta pNa) were measured in resting cells of Fibrobacter succinogenes by in vivo Na-23 nuclear magnetic resonance using Tm(DOTP)(5-) [thulium(III) 1,4,7,10-tetraazacyclododecane-N 'N " ,N ' ' ' -tetramethyle nephosphonatel as the shift reagent. This bacterium was able to maintain a Delta pNa of -55 to -40 mV for extracellular sodium concentrations ranging from 30 to 200 mM. Depletion of Na+ ions during the washing steps led to ir reversible damage (modification of glucose metabolism and inability to main tain a sodium gradient).