Desulfovibrionales

Desulfovibrionales is an order of bacteria within the class Deltaproteobacteria best known for dissimilatory sulfate reduction. Members are generally Gram-negative, curved rods or vibrios, and many are motile by polar flagella. They are strict or facultative anaerobes that inhabit a variety of anoxic environments, including marine and freshwater sediments, wetlands, subsurface ecosystems, wastewater systems, and oil-bearing reservoirs.

Metabolism and physiology: Desulfovibrionales are sulfate-reducing bacteria (SRB). They harvest energy by oxidizing organic compounds or hydrogen while reducing sulfate to sulfide. Common electron donors include lactate, pyruvate, ethanol, formate, and hydrogen; the terminal electron acceptor is sulfate, with sulfite or thiosulfate used by some members. The enzymatic machinery for dissimilatory sulfate reduction includes the DsrAB complex and associated proteins. Many species form biofilms and can tolerate varying redox conditions, though oxygen sensitivity remains high.

Ecology and significance: They play a central role in the sulfur cycle of anoxic environments and contribute to sulfidogenesis, which can result in metal corrosion and souring of oil pipelines, as well as odorous hydrogen sulfide production. In addition to environmental roles, Desulfovibrio species occur in the gastrointestinal tracts of animals including humans, where they interact with other microbes and participate in sulfur metabolism. The genus Desulfovibrio is the best studied within the group, including model organism Desulfovibrio vulgaris.

Taxonomy and diversity: The order contains several genera, dominated by the Desulfovibrio lineage. Molecular studies have refined relationships within the group, but the core trait remains dissimilatory sulfate reduction by anaerobic bacteria.