Diversity of sulfate-reducing bacteria in oxic and anoxic regions of a microbial mat characterized by comparative analysis of dissimilatory sulfite reductase genes

Sequence analysis of genes encoding dissimilatory sulfite reductase (DSR) w as used to identify sulfate-reducing bacteria in a hypersaline microbial ma t and to evaluate their distribution in relation to levels of oxygen. The m ost highly diverse DSR sequences, most related to those of the Desulfonema- like organisms within the delta-proteobacteria, were recovered from oxic re gions of the mat. This observation extends those of previous studies by us and others associating Desulfonema-like organisms with oxic habitats.