In Vivo 23 Na Nuclear Magnetic Resonance Study of Maintenance of a Sodium Gradient in the Ruminal Bacterium Fibrobacter succinogenes S85

Abstract
Sodium gradients (ΔpNa) were measured in resting cells of Fibrobacter succinogenes by in vivo 23 Na nuclear magnetic resonance using Tm(DOTP) 5− [thulium(III) 1,4,7,10-tetraazacyclododecane- N ′, N ′′, N ′′′-tetramethylenephosphonate] as the shift reagent. This bacterium was able to maintain a ΔpNa 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 irreversible damage (modification of glucose metabolism and inability to maintain a sodium gradient).