X-ray microanalysis of intracellular ions in the anaerobic halophilic eubacterium Haloanaerobium praevalens

The intracellular concentrations of Na⁺, K⁺, and Cl^- of the anaerobic halophilic eubacterium Haloanaerobium praevalens were assayed by means of X- ray microanalysis with the transmission electron microscope. Apparent intracellular cation concentrations between 1.22 and 1.91 M and chloride concentrations of 0.93-1.57 M were measured in cells growing exponentially in 2.6 M total salts. In exponentially growing cells, K⁺ was the major cation (70% of the cation sum). Stationary phase cells showed a high variability among individual cells, some of the cells containing higher Na⁺ than K⁺ concentrations.