[The character of K+ uptake in anaerobically grown S. typhimurium]

Tre character of K+ uptake in anaerobically grown S. typhimurium LT-2 is studied. In the alkaline media with glucose and moderate K+ activity these bacteria uptake K+ in two steps, the first of which has a high rate of K+ uptake, Km 2.1 mM and Vmax 0.44 mM/g. min and is sensitive to the medium osmolarity. Bacteria transfer from the media with high osmolarity to that with low one leads to a decrease of K+ uptake at the first step. The second increase of the medium osmolarity turns on the rapid K+ uptake only at alkaline pH. K+ uptake at the first step is inhibited by DCC and protonophores. In the absence of phosphate in the medium arsenate blocks K+ uptake at the first step, and when phosphate is available arsenate decreases K+ uptake. Valinomycin decreases the rate of K+ uptake. K+ uptake at the first step in S. typhimurium proceeds via Trk-like system which requires for K+ uptake both ATP and delta mu H+.