Glucose uptake by free living and bacteroid forms of Rhizobium leguminosarum

Free living cells of Rhizobium leguminosarum contain a constitutive glucose uptake system, except when they are grown on succinate, which appears to prevent its formation. Bacteroids isolated from Pisum sativum L fail to accumulate glucose although they actively take up ¹⁴C-succinate. Glucose uptake in free living cells is an active process since uptake was inhibited by azide, cyanide, dinitrophenol and carbonyl-m-chlorophenyl hydrazone but not by fluoride or arsenate. The non-metabolizable analogue -methyl glucose was extracted unchanged from cells, showing that it was not phosphorylated during its transport. Galactose also appears to the transported via the glucose uptake system. Organic acids, amino acids and polyols had no effect on the actual uptake of glucose. The K_m for -methyl glucose uptake was 2.9×10^-4 M.