The effect of anions on K+-binding in aHalobacterium species

Abstract

Trinitrocresolate (TNC) at a concentration of 2×10⁻³ m brings about rapid loss of K from starvingHalobacterium cells. Higher concentrations of other anions such as salicylate, thiocyanate, and perchlorate produce a similar effect. The TNC-induced K loss is not significantly reversed when TNC is removed from the ambient medium. The rate of K loss in the presence of 2×10⁻³ m TNC is only slightly increased by the temperature in the ranges of 30 to 40°C and 0 to 20°C; between 20 and 30°C, however, the rate increases 10-fold. The K loss was partly replaced by Na⁺. These data are interpreted in terms of the hypothesis that K is retained in starvingHalobacterium sp. not by active transport, but rather by selective binding on loci which are modified by TNC.