Lawrence Berkeley National Laboratory

Deletion of the qmoABC and a hypothetical protein (HP) (DVU0848-51) in the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough resulted in an inability to reduce sulfate. No suppressor mutations appeared in cultures of the deletion incubated in the presence of sulfate. Curiously, the D(qmoABC, HP) mutant was also unable to ferment pyruvate. Respiration of sulfate and fermentation of pyruvate was restored by supplying the qmoABC, HP genes. In order to verify if the hypothetical protein at the end of the operon contributes to the ability of this organism to reduce sulfate and ferment pyruvate, two complemented strains were constructed: both with the qmoABC genes, one with and one without the hypothetical protein. These two strains are compared for their ability to grow on sulfate as the sole electron-donor. Latest results suggest an integral role of the hypothetical protein in sulfate reduction.