Beggiatoa
| Beggiatoa | |
|---|---|
| Scientific classification | |
| Domain: | Bacteria |
| Phylum: | Proteobacteria |
| Class: | Gammaproteobacteria |
| Order: | Thiotrichales |
| Family: | Thiotrichaceae |
| Genus: |
Beggiatoa Trevisan 1842 |
| Species | |
Beggiatoa is a genus of bacteria in the order Thiotrichales. They are named after the Italian medic and botanist F.S. Beggiato. The organisms live in sulfur-rich environments. During his research in Anton de Bary’s laboratory of botany in 1887, Russian botanist Sergei Winogradsky found that Beggiatoa oxidized hydrogen sulfide (H2S) as an energy source, forming intracellular sulfur droplets. Winogradsky referred to this form of metabolism as inorgoxidation (oxidation of inorganic compounds). The finding represented the first discovery of lithotrophy. Up to now there is only one species of this genus known (Beggiatoa alba).
Beggiatoa can be found in marine or freshwater environments. They can usually be found in habitats that have high levels of hydrogen sulfide. These environments include cold seeps, sulfur springs, sewage contaminated water, mud layers of lakes, and near deep hydrothermal vents. Beggiatoa can also be found in the rhizosphere of swamp plants.
The colorless cells are disk-shaped or cylindrical, arranged in long filaments with a cell diameter that can measure between 12 and 160 micrometres (different subspecies). A massive central vacuole is used for accumulation of nitrate, presumably for use as an electron acceptor in anaerobic sulfide oxidation. The filaments are surrounded by slime and can move by gliding.
Beggiatoa can grow chemoorgano-heterotrophically by oxidizing organic compounds to carbon dioxide in the presence of oxygen, although high concentrations of oxygen can be a limiting factor. Organic compounds are also the carbon source for biosynthesis. Some species may oxidize hydrogen sulfide to elemental sulfur as a supplemental source of energy (facultatively litho-heterotroph). Produced sulfur is stored intracellularly.
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Wikipedia