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Thiomargarita namibiensis is a Gram-negative coccoid bacterium, found in the ocean sediments of the continental shelf of Namibia. It is the largest bacterium ever discovered, as a rule 0.1–0.3 mm (100–300 μm) in diameter, but sometimes attaining 0.75 mm (750 μm). Cells of Thiomargarita namibiensis are large enough to be visible to the naked eye. Although the species holds the record for the largest known bacterium, Epulopiscium fishelsoni – previously discovered in the gut of surgeonfish – grows slightly longer, but narrower.
The green sulfur bacteria are a phylum of obligately anaerobic photoautotrophic bacteria that metabolize sulfur.
The Desulfobacteraceae are a family of Thermodesulfobacteriota. They reduce sulfates to sulfides to obtain energy and are strictly anaerobic. They have a respiratory and fermentative type of metabolism. Some species are chemolithotrophic and use inorganic materials to obtain energy and use hydrogen as their electron donor.
The Chromatiaceae are one of the two families of purple sulfur bacteria, together with the Ectothiorhodospiraceae. They belong to the order Chromatiales of the class Gammaproteobacteria, which is composed by unicellular Gram-negative organisms. Most of the species are photolithoautotrophs and conduct an anoxygenic photosynthesis, but there are also representatives capable of growing under dark and/or microaerobic conditions as either chemolithoautotrophs or chemoorganoheterotrophs.
Sulfur-reducing bacteria are microorganisms able to reduce elemental sulfur (S0) to hydrogen sulfide (H2S). These microbes use inorganic sulfur compounds as electron acceptors to sustain several activities such as respiration, conserving energy and growth, in absence of oxygen. The final product or these processes, sulfide, has a considerable influence on the chemistry of the environment and, in addition, is used as electron donor for a large variety of microbial metabolisms. Several types of bacteria and many non-methanogenic archaea can reduce sulfur. Microbial sulfur reduction was already shown in early studies, which highlighted the first proof of S0 reduction in a vibrioid bacterium from mud, with sulfur as electron acceptor and H2 as electron donor. The first pure cultured species of sulfur-reducing bacteria, Desulfuromonas acetoxidans, was discovered in 1976 and described by Pfennig Norbert and Biebel Hanno as an anaerobic sulfur-reducing and acetate-oxidizing bacterium, not able to reduce sulfate. Only few taxa are true sulfur-reducing bacteria, using sulfur reduction as the only or main catabolic reaction. Normally, they couple this reaction with the oxidation of acetate, succinate or other organic compounds. In general, sulfate-reducing bacteria are able to use both sulfate and elemental sulfur as electron acceptors. Thanks to its abundancy and thermodynamic stability, sulfate is the most studied electron acceptor for anaerobic respiration that involves sulfur compounds. Elemental sulfur, however, is very abundant and important, especially in deep-sea hydrothermal vents, hot springs and other extreme environments, making its isolation more difficult. Some bacteria – such as Proteus, Campylobacter, Pseudomonas and Salmonella – have the ability to reduce sulfur, but can also use oxygen and other terminal electron acceptors.
Bacterial phyla constitute the major lineages of the domain Bacteria. While the exact definition of a bacterial phylum is debated, a popular definition is that a bacterial phylum is a monophyletic lineage of bacteria whose 16S rRNA genes share a pairwise sequence identity of ~75% or less with those of the members of other bacterial phyla.
Thermoanaerobacter is a genus in the phylum Bacillota (Bacteria). Members of this genus are thermophilic and anaerobic, several of them were previously described as Clostridium species and members of the now obsolete genera Acetogenium and Thermobacteroides
"Candidatus Scalindua" is a bacterial genus, and a proposed member of the order Planctomycetales. These bacteria lack peptidoglycan in their cell wall and have a compartmentalized cytoplasm. They are ammonium oxidizing bacteria found in marine environments.
Rhodoblastus acidophilus, formerly known as Rhodopseudomonas acidophila, is a gram-negative purple non-sulfur bacteria. The cells are rod-shaped or ovoid, 1.0 to 1.3 μm wide and 2 to 5 μm long. They are motile by means of polar flagella, and they multiply by budding. The photopigments consist of bacteriochlorophyll a and carotenoids of the spirilloxanthin series. All strains can grow either under anaerobic conditions in the light or under microaerophilic to aerobic conditions in the dark.
Desulfuromonas michiganensis is a species of tetrachloroethene-reducing, acetate-oxidizing anaerobic bacteria.
Desulfurella acetivorans is a thermophilic acetate-oxidizing sulfur-reducing eubacterium. It is Gram-negative, short rod-shaped, motile, with a single polar flagellum.
Desulfocapsa thiozymogenes is an anaerobic, gram-negative bacterium. It disproportionates elemental sulfur. It is the type species of its genus.
Marinitoga piezophila is a species of rod-shaped, thermo-piezophilic bacteria. It is, anaerobic, chemo-organotrophic, sulfur-reducing, motile, have a mean length of 1-1.5 micrometres and stains Gram-negative. The type strain is KA3T.
Desulfuromonas is a Gram negative bacterial genus from the family of Desulfuromonadaceae. Desulfuromonas can reduce elemental sulfur to H2S. Desulfuromonas occur in anoxic sediments and saline lakes.
Caldimicrobium is a genus of bacteria from the family of Thermodesulfobacteriaceae.
Geopsychrobacter is a genus of bacteria from the order Desulfuromonadales.
Microbial oxidation of sulfur is the oxidation of sulfur by microorganisms to build their structural components. The oxidation of inorganic compounds is the strategy primarily used by chemolithotrophic microorganisms to obtain energy to survive, grow and reproduce. Some inorganic forms of reduced sulfur, mainly sulfide (H2S/HS−) and elemental sulfur (S0), can be oxidized by chemolithotrophic sulfur-oxidizing prokaryotes, usually coupled to the reduction of energy-rich oxygen (O2) or nitrate (NO3−). Anaerobic sulfur oxidizers include photolithoautotrophs that obtain their energy from sunlight, hydrogen from sulfide, and carbon from carbon dioxide (CO2).
Thioflavicoccus is a Gram-negative, obligately phototrophic, strictly anaerobic and motile genus of bacteria from the family of Chromatiaceae with one known species.
"CandidatusThiodictyon syntrophicum" is a gram-negative bacterium classified within purple sulfur bacteria (PSB). "Ca. T. syntrophicum" grows best under micro-oxic and low light conditions. There has only been one successful enrichment of "Ca. T. syntrophicum"; "Ca. T. syntrophicum" strain Cad16T.
Ann Patricia Wood is a retired British biochemist and bacteriologist who specialized in the ecology, taxonomy and physiology of sulfur-oxidizing chemolithoautotrophic bacteria and how methylotrophic bacteria play a role in the degradation of odour causing compounds in the human mouth, vagina and skin. The bacterial genus Annwoodia was named to honor her contributions to microbial research in 2017.
References
- ↑ Pfennig, Norbert; Biebl, Hanno (1976). "Desulfuromonas acetoxidans gen. nov. and sp. nov., a new anaerobic, sulfur-reducing, acetate-oxidizing bacterium". Archives of Microbiology. 110 (1): 3–12. doi:10.1007/BF00416962. ISSN 0302-8933.
