Sulfur disproportionation by the facultative anaerobe Pantoea agglomerans SP1 as a mechanism for chromium(VI) reduction

The facultative anaerobe Pantoea agglomerans SPl was previously shown to couple anaerobic growth to the dissimilatory reduction of a variety of electron acceptors, including Fe(III), Mn(IV), and Cr(VI), but not sulfate. In this study, we describe the additional capacity of this organism to grow via the disproportionation of elemental sulfur to sulfate and sulfide, a process that has previously only been reported in strictly anaerobic members of the δ-Proteobacteria. The sulfide scavengers, Fe(III) Mn(IV), and for the first time, Cr(VI), were found to enhance growth coupled to S⁰-disproportionation. To our knowledge, this is the first facultative anaerobe reported to couple growth to sulfur disproportionation. This organism may play a role in the attenuation of Cr(VI) pollution.