Glucose transport system in a facultative iron-oxidizing bacterium, Thiobacillus ferrooxidans

Properties of a heat-labile glucose transport system in Thiobacillus ferrooxidans strain AP-44 were investigated with iron-grown cells. [14C]glucose was incorporated into cell fractions, and the cells metabolized [14C]glucose to 14CO2. Amytal, rotenone, cyanide, azide, 2,4-dinitrophenol, and dicyclohexylcarbodiimide strongly inhibited [14C]glucose uptake activity, suggesting the presence of an energy-dependent glucose transport system in T. ferrooxidans. Heavy metals, such as mercury, silver, uranium, and molybdate, markedly inhibited the transport activity at 1 mM. When grown on mixotrophic medium, the bacteria preferentially utilized ferrous iron as an energy source. When iron was exhausted, the cells used glucose if the concentration of ferrous sulfate in the medium was higher than 3% (wt/vol). However, when ferrous sulfate was lower than 1%, both of the energy sources were consumed simultaneously.