Anaerobic reduction and oxidation of quinone moieties and the reduction of oxidized metals by halorespiring and related organisms

Halorespiring microorganisms have been detected in soils that were not polluted with chlorinated compounds. In this study, we describe alternative electron acceptor utilization by some halorespiring bacteria and phylogenetically related bacteria. It appears that oxidized metals like selenate, arsenate and manganese are rather common electron acceptors for halorespiring species of Desulfitobacterium and Sulfurospirillum and related bacteria. All tested microorganisms are able to reduce anthraquinone-2,6-disulfonate (AQDS) and four tested organisms ( Desulfitobacterium hafniense DP7, Sulfurospirillum barnesii, Sulfurospirillum deleyianum and Sulfurospirillum arsenophilum) are able to oxidize reduced anthrahydroquinone-2,6,-disulfonate (AH 2QDS) as well. The characteristic to reduce oxidized metals, and to reduce and oxidize quinone moieties coupled to energy conservation is a likely explanation for the presence of halorespiring microorganisms in unpolluted soils.