Desulfovibrio desulfuricans is a species of sulfate-reducing bacteria (SRB) recognized for its unique metabolism in oxygen-free environments. These widespread microorganisms are defined by their method of energy production, which is a component of certain biogeochemical cycles. Since its initial isolation, the species has been studied for its environmental, industrial, and health implications.
Core Biological Characteristics
Desulfovibrio desulfuricans is a Gram-negative bacterium, a classification referring to its cell wall composition. It is shaped like a curved rod, or “vibrio,” and is motile, propelling itself using whip-like appendages called flagella.
The bacterium’s defining feature is its metabolism. As a strict anaerobe, oxygen is toxic to it. To produce energy, it performs respiration that uses sulfate instead of oxygen to receive electrons in its energy-generating process, a method sometimes described as “breathing” sulfate. This process is central to its survival.
Through this metabolic pathway, D. desulfuricans consumes organic compounds like lactate and pyruvate for energy. A primary byproduct of this sulfate respiration is hydrogen sulfide (H2S), a gas known for its “rotten egg” smell. The production of H2S is the foundation for the bacterium’s effects on natural and industrial settings.
Environmental and Industrial Roles
In nature, Desulfovibrio desulfuricans is a player in the global sulfur cycle. It thrives in oxygen-free locations like marsh sediments, the deep sea, and wastewater treatment facilities. In these habitats, its production of hydrogen sulfide contributes to the cycling of sulfur.
This bacterium also has a positive function in bioremediation. The hydrogen sulfide it generates reacts with heavy metal ions in water, causing them to precipitate into solid, insoluble metal sulfides. This process makes the metals easier to remove and has been explored for cleaning up water contaminated with toxic metals like cadmium.
Despite its utility, D. desulfuricans is a concern for industries like oil and gas. Its presence in pipelines and storage facilities leads to microbiologically influenced corrosion (MIC). The bacterium forms biofilms on iron and steel, and the hydrogen sulfide it releases is highly corrosive, eating away at the metal and causing structural damage.
The bacterium is also responsible for the “souring” of oil and gas reserves. When it grows in reservoirs, the hydrogen sulfide it produces dissolves into the petroleum, increasing its sulfur content. This “sour” crude oil is less valuable and more hazardous, requiring extra refining to remove the sulfur compounds.
Relationship to Human Health
Desulfovibrio desulfuricans is also a member of the human gut microbiota. In many individuals, it is a harmless resident of the gastrointestinal tract. However, it can become a pathobiont, an organism that can be associated with disease when it overgrows.
Research points to a correlation between high levels of this bacterium and certain inflammatory conditions, most notably Inflammatory Bowel Disease (IBD). Studies show the abundance of Desulfovibrio species is often increased in samples from patients with IBD compared to healthy individuals.
The proposed mechanism relates to its metabolic byproduct, hydrogen sulfide. While H2S has signaling roles at low concentrations, excessive production in the gut is considered toxic. It is thought to damage the cells lining the colon by interfering with their primary energy source, a fatty acid called butyrate. This impairment can contribute to the chronic inflammation that characterizes IBD.
Current research establishes a strong correlation rather than direct causation, and scientists are still working to understand the bacterium’s precise role in disease. Emerging studies are also exploring potential links between D. desulfuricans and other health issues like liver disease and atherosclerosis, suggesting its influence may extend beyond the gut.