Stable sulfur isotope fractionation during the reduction of thiosulfate byDethiosulfovibrio russensis

Stable sulfur isotope fractionation was investigated during reduction of th iosulfate by growing batch cultures of Dethiosulfovibrio russensis at a cel l-specific reduction rate of 2.4+/-0.72 fmol cell(-1) d(-1) (28 degreesC). Citrate was used as carbon and energy source. The hydrogen sulfide produced by this sulfur- and thiosulfate-reducing bacterium was depleted in S-34 by 11 parts per thousand compared to total thiosulfate sulfur, in agreement w ith previous results observed for sulfate-reducing bacteria. This indicates the operation of a similar pathway for thiosulfate reduction in these phyl ogenetically different bacteria.