No unique biological role for rubidium has been identified, but Rb+ can serve as a
biochemical analog to K+ and
NH4+. In the absence of K+,
Rb+ was found to restore normal or near normal growth in
faecalis and Lactobacillus casei (MacLeod and Snell, 1948), Rhodopseudomonas capsulata (Jasper, 1978), and Oceanomonas baumannii (Brown and Cummings, 2001). Rb+ has been shown to effectively substitute for K+ in the
biosynthesis of the pigment prodigiosin in Serratia marcescens (Bruce and Duff, 1968) and in the activation of aldehyde dehydrogenase in Saccharomyces cerevsiae
(Black, 1951). Rb+ can also replace NH4+ in the activation of NADP-specific glutamate
dehydrogenase in the fungus Neurospora crassa (Wootton, 1983). Activation of selenophosphate synthetase in E. coli requires
Mg2+ plus either K+, NH4+, or Rb+ (Veres et al, 1994). Rb+ import and export can be mediated by
monovalent cation/H+ antiport systems in bacteria (Brey et al, 1980) and yeasts (Kinclova et al, 2001; Lapathitis and Kotyk, 1998). Rb+ uptake via a cation uniport in Fusarium oxysporum
var. lini has been proposed (Cabello-Hurtado, 2000). Rb+ can also induce competence for plasmid uptake in
S. cerevisiae (Ito et al, 1983).
For more information:
Medline for rubidium metabolism AND bacteria
Black, S. Yeast aldehyde dehydrogenase. Arch Biochem Biophys. 1951;34:86-97.
MacLeod RA, Snell EE. The effect of related ions on the potassium requirements of lactic acid bacteria. J Biol Chem.