GROWTH OF WOLINELLA-SUCCINOGENES WITH POLYSULFIDE AS TERMINAL ACCEPTOR OF PHOSPHORYLATIVE ELECTRON-TRANSPORT

Polysulphide was formed according to reaction (1), when tetrathionate was S4O6(2-) + HS- --> 2S2O3(2-) + S(O) + H+ added to an anaerobic buffer (pH 8.5) containing excess sulphide. S(O) denotes the zero oxidation state sulphur in the polysulphide mixture Sn2-. The addition of formate to the polysulphide solution in the presence of Wolinella succinogenes caused the reduction of polysulphide according to reaction (2). The bacteria grew in a medium containing formate and sulphide, HCO2- + S(O) + H2O --> HCO3- + HS- + H+ when tetrathionate was continuously added. The cell density increased proportional to reaction (3) which represents the sum of reactions (1) and HCO2- + S4O6(2-) + H2O --> HCO3- + 2S2O3(2-) + 2H+ (3) (2). The cell yield per mol formate was nearly the same as during growth on formate and elemental sulphur, while the velocity of growth was greater. The specific activities of polysulphide reduction by formate measured with bacteria grown with tetrathionate or with elemental sulphur were consistent with the growth parameters. The results suggest that W. succinogenes grow at the expense of formate oxidation by polysulphide and that polysulphide is an intermediate during growth on formate and elemental sulphur.