FIG 10.

Estimation of intracellular K⁺ content in E. coli strain TK2420 deficient in major K⁺ transport systems and its complemented strains. Strains were grown to mid-exponential phase in K⁺-rich KLM medium and incubated in MMGK for 2 h to deplete cellular K⁺ levels. Cells were subsequently supplemented with 5 mM KCl and aliquots sampled over time to measure intracellular K⁺ content using ICP-OES. Data are representative of two independent experiments performed in duplicate. Error bars represent means ± SD. Repeated-measures ANOVA was used for statistical analysis between different time points compared with the initial time point (*) and between mutants and E. coli strain TK2420 harboring an empty vector at the same time point (#).