Are thiosulfate and trithionate intermediates in dissimilatory sulfate reduction?

The fate of 35-S during anaerobic metabolism of [35-S]sulfate, [35-S]thiosulfate, and [35-S]sulfate plus unlabeled thiosulfate by washed cell suspensions of Desulfovibrio spp, and of [35-S]thiosulfate by growing D. desulfuricans was examined. The results appear to be inconsistent with the hypothesis that thiosulfate is an intermediate in sulfate reduction. Since thiosulfate was produced from trithionate, the latter is also unlikely to be an intermediate in the reduction pathway. Extracts of D. desulfuricans catalysed exchange between sulfite and the sulfonate group of thiosulfate.