1. IDENTIFYING CHARACTERISTICS
2. TAXONOMIC DESCRIPTIONAll Desulfovibrio are sulfate reducing bacteria and are gram negative, non spore forming medium sized curved rod shaped cells that contain desulfoviridin and are motile. Their cellular morphology and biochemical characteristics are very similar to those of Desulfomicrobium, Desulfofustis, Desulfotomaculum, and Desulforhopalus. All of these bacteria do NOT oxidize acetate, thus they are placed in a separate group away from the acetate oxidizing sulfate reducers. The distinguishing characteristics of Desulfovibrio species are that they contain desulfoviridin. Desulfovibrio oxidize their energy source to that of acetate and excrete this as their end product. Desulfovibrio also uses hydrogen, lactate, and pyruvate as electron donrs. This genus can grow easily on a sulfate-lactate medium in the absence of oxygen. There are a number of species fwithin the genus Desulfovibrio. This link will provide the names of all the species.
The picture (above left) shows a 3-dimensional main chain fold of Desulfovibrio vulgaris.
3. ISOLATION AND ECOLOGYMembers of the genus Desulfovibrio commonly reside in the soil and aquatic habitats. Since these organisms are strict anaerobes, both aquatic and terrestrial environments are made anoxic as a result of microbial decomposition. The surrounding elements in such an environment are rich in organic material and in sulfate. Isolation of Desulfovibrio is facilitated by using the anoxic lactate-sulfate medium with ferrous iron incorporated into the culture. As the sulfate is reduced to sulfite, the sulfite interact with the ferrous iron to generate a black medium (see Figure B to the left). This new medium is chemically called ferrous sulfide and it is insoluble. The blackening of the culture indicates that sulfate reduction is taking place and that the iron is acting as a detoxifier for the harmful sulfide; thus, enabling a higher growth yield for the sulfate-reducing bacteria to grow. To further isolate the sulfate-reducing bacteria, streaking can be used both on a Petri plate or in roll tubes. The shaken tube method involves placing a small amount of liquid with the bacteria in the agar growth medium and diluted. Once the medium is solidified, black colonies of the bacteria will appear and can be cultivated into a pure culture. Due to how common Desulfovibrio is found in both aquatic and terrestrial habitats, this genus is the most studied of the sulfate-reducing proteobacteria.
The above picture shows Desulfovibrio in a lactose-sulfate medium (B), and under a bright field microscope (C).
McDougall, R., J. Robson, D. Paterson, and W. Tee. 1997. Bacteremia caused by a recently described novel Desulfovibrio species. Journal of Clinical Microbiology. 35:1805-1808.
Madigan, M., Martinko, J., and Parker J. 2000. Brock Biology of Microorganisms. Prentice-Hall. Upper Saddle River, NJ. 498-502 pp.
Holt, J. G., N. R. Krieg, P. H. A. Sneath, J. T. Staley, and S. T. Williams.
1994. Bergey's Manual of Systematic Bacteriology. Williams and Wilkins. Baltimore, Maryland. 235-242 pp.
Methanogenesis and Desulfovibrio
Quantitative list of Desulfovibrio species
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