CHARACTERIZATION OF URANIUM MINE ISOLATES AND LABORATORY CULTURES OF THIOBACILLUS FERROOXIDANS WITH EMPHASIS ON THE OXIDATION AND CELLULAR ACCUMULATION OF URANIUM AND BIOENERGETIC COMPARISON WITH IRON

Five strains of Thiobacillus ferrooxidans, which included three recent isolates from a uranium mine, possessed flagella. Three of the strains had several pili per cell. The dimensions, fine structure, and orientation of the flagella were different. Both polar and peritrichous flagella were observed, indicating strain-dependent ultrastructural variation in acidophilic thiobacilli.; The oxidation of uranous compounds by washed cell suspensions of T.ferrooxidans and T.acidophilus was monitored with a Clark oxygen electrode. The bacteria were able directly to oxidize U-IV. The rates of oxygen uptake were dependent on: the cell concentration; the previous growth history of the organism; the amounts of U-IV and of inhibitors; pH and the presence of iron sulfates.; The stoichiometric oxidation of uranous- to uranyl-uranium by T.ferrooxidans was demonstrated. Fixation of ('14)CO(,2) and the effect of inhibitors demonstrate that energy is conserved during the oxidation and used for energy-dependent "reverse electron flow" and carbon dioxide fixation.; Kinetic constants for the oxidation of uranous and ferrous ions by T.ferrooxidans were estimated. The kinetics indicate a direct biological mechanism for uranium oxidation. The complex interrelations of ferric, uranyl and uranous ion inhibition are considered.; Isoprenoid quinones were extracted from T.ferrooxidans by three different methods. Ubiquinone-8 was the only isoprenoid quinone detected and it was isolated and identified by thin layer chromatography, high performance liquid chromatography, and mass spectrometry.; The uptake and cellular distribution of UO(,2)('2+) was investigated in washed cell suspensions of T.ferrooxidans.