Transport of inorganic phosphate in Streptomyces granaticolor was characterized in two growth stages; kinetic parameters were determined and two transport systems were found in both stages, with the following values: KT1 = 0.06 mM, Jlim1 = 0.95 nmol min-1 (mg DS)-1, and KT2 = 1.80 mM, Jlim2 = 25 nmol min-1 (mg DS)-1. Both systems require metabolic energy and substrates, such as sugars or polyols; when alanine was used or the energy source was omitted, the kinetic parameters changed in both systems. Both systems were inhibited by the ionophore cccp with identical k(i). KCN, an inhibitor or terminal cytochrome oxidase, inhibited the uptake of phosphate only partially, the uptake was inhibited completely when also the inhibitor of the alternative oxidative pathway (salicylhydroxamic acid) was added. Antimycin A inhibited the uptake completely. Arsenate inhibited competitively.

Institute of Microbiology Czech Academy of Sciences Praha Czech Republic