FIG 6.

Growth experiments with KtrCD variants highlight the relevance of the G282V mutation for the physiology of B. subtilis. B. subtilis strains expressing KtrCD, KtrD, and the mutated variants as the only potassium uptake systems were cultivated in MSSM medium with 50 mM KCl and ammonium. Cells were harvested and washed, and the OD₆₀₀ was adjusted to 1.0. Serial dilutions were added dropwise to MSSM plates with the indicated potassium concentration and ammonium or glutamate. The mutation in the ktrD gene was introduced into the chromosome via CRISPR-Cas9 gene editing.