The Thiotrichales are an order of Proteobacteria, including Thiomargarita namibiensis, the largest known bacterium.[2]

They also include certain pathogens, such as Francisella tularensis which causes tularemia (rabbit fever).[2]

Sulphide bacteria crop
Thiomargarita namibiensis
Scientific classification



  1. ^ a b c d "Thiotrichales".
  2. ^ a b George M. Garrity: Bergey's Manual of Systematic Bacteriology. 2. Auflage. Springer, New York, 2005, Volume 2: The Proteobacteria, Part B: The Gammaproteobacteria

Achromatium is a genus in the phylum Proteobacteria (Bacteria).


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. Two species of Beggiatoa have been formally described: the type species Beggiatoa alba, and Beggiatoa leptomitoformis, the latter of which was only published in 2017.

Beggiatoa leptomitoformis

Beggiatoa leptomitoformis is a chemolithoautotrophic bacterium from the genus of Beggiatoa which has been isolated from wastewater from Moscow in Russia.

Chromobacteriosis infection

Chromobacteriosis infections are a cutaneous condition caused by chromobacteria characterized by fluctuating abscesses.


Cycloclasticus is a genus in the phylum Proteobacteria (Bacteria).


Francisella is a genus of pathogenic, Gram-negative bacteria. They are small coccobacillary or rod-shaped, nonmotile organisms, which are also facultative intracellular parasites of macrophages. Strict aerobes, Francisella colonies bear a morphological resemblance to those of the genus Brucella.The genus was named in honor of American bacteriologist Edward Francis, who, in 1922, first recognized F. tularensis (then named Bacterium tularensis) as the causative agent of tularemia.

Francisella piscicida

Francisella piscicida is a bacterium present in Atlantic cod. It is a serious disease present in Norwegian cod farming.

Francisella tularensis

Francisella tularensis is a pathogenic species of Gram-negative coccobacillus, an aerobic bacterium. It is nonspore-forming, nonmotile, and the causative agent of tularemia, the pneumonic form of which is often lethal without treatment. It is a fastidious, facultative intracellular bacterium, which requires cysteine for growth. Due to its low infectious dose, ease of spread by aerosol, and high virulence, F. tularensis is classified as a Tier 1 Select Agent by the U.S. government, along with other potential agents of bioterrorism such as Yersinia pestis, Bacillus anthracis, and Ebola virus. When found in nature, Francisella tularensis can survive for several weeks at low temperatures in animal carcasses, soil, and water. In the laboratory, F. tularensis appears as small rods (0.2 by 0.2 µm), and is grown best at 35-37°C.

Hydrogenovibrio crunogenus

Hydrogenovibrio crunogenus (basonym Thiomicrospira crunogena) is a colorless, sulfur-oxidizing bacterium first isolated from a deep-sea hydrothermal vent. It is an obligate chemolithoautotrophic sulfur oxidizer and differs from other species of this genus by its DNA base composition and by its growth rate and optimal pH in thiosulfate medium. ATCC 35932T (=LMD 84.00T) is the type strain of the species. It was originally published in the genus Thiomicrospira as Thiomicrospira crunogena but was reclassified to the genus Hydrogenovibrio in 2017, resulting a grammatical gender change of the specific epithet from crunogena to crunogenus. The genome sequence of H. crunogenus XCL-2 has been published but that of the type strain has not yet been undertaken.

Leucothrix (bacteria)

Leucothrix is a genus of large, filamentous bacteria, which live as epiphytes in marine habitats.


The Oceanospirillales are an order of Proteobacteria with seven families.


The Piscirickettsiaceae are a family of Proteobacteria. All species are aerobes found in water.

The species Piscirickettsia salmonis is a fish pathogen and causes piscirickettsiosis in salmonid fishes.

It lives in cells of infected hosts and cannot be cultured on artificial media. Piscirickettsia salmonis is nonmotile, whereas the other five genera are motile by using a single flagellum.


Thiolava, represented by its sole species Thiolava veneris (meaning Venus's hair), is a genus of bacteria discovered growing in stringlike mats after an eruption of the submarine volcano Tagoro near the Canary Islands. The International Institute of Species Exploration named Thiolava veneris one of its 2018 Top 10 New Species.


Thiomargarita is a genus (family Thiotrichaceae) which includes the vacuolate sulfur bacteria species Thiomargarita namibiensis, Candidatus Thiomargarita nelsonii, and Ca. Thiomargarita joergensii.

Representatives of this genus can be found in a variety of environments that are rich in hydrogen sulfide, including methane seeps, mud volcanoes, brine pools, and organic-rich sediments such as those found beneath the Benguela Current and Humboldt Current. These bacteria are generally considered to be chemolithotrophs that utilize reduced inorganic species of sulfur as metabolic electron donors to produce energy for the fixation of carbon into biomass. Carbon fixation occurs via the Calvin Benson Bassham cycle and possibly the reverse Krebs cycle.

Thiomargarita namibiensis

Thiomargarita namibiensis is a Gram-negative coccoid Proteobacterium, 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 bacterium, Epulopiscium fishelsoni – previously discovered in the gut of surgeonfish – grows slightly longer, but narrower.

Thiomargarita means "sulfur pearl". This refers to the appearance of the cells; they contain microscopic sulfur granules that scatter incident light, lending the cell a pearly lustre. Like many coccoid bacteria such as Streptococcus, their cellular division tends to occur along a single axis, causing their cells to form chains, rather like strings of pearls. The species name namibiensis means "of Namibia".


Thioploca is a genus of filamentous sulfur bacteria which occurs along 3,000 kilometres (1,900 mi) of coast off the west of South America. A large vacuole occupies more than 80% of their cell volume and contains sulfide and nitrate which they use to make energy for their metabolism by oxidising sulfide with nitrate. The concentration of nitrate in the vacuole is extremely high (500 mM) even though the sediments in which they live are relatively very low in nitrogen (25 μM). Because they use both sulfur and nitrogen compounds they may provide an important link between the nitrogen and sulfur cycles. They secrete a sheath of mucus which they use as a tunnel to travel between the sulfide containing sediment and the nitrate containing sea water.

Thioploca araucae

Thioploca araucae is a marine thioploca from the benthos of the Chilean continental shelf. It is a colonial, multicellular, gliding trichomes of similar diameter enclosed by a shared sheath. It possesses cellular sulfur inclusions located in a thin peripheral cytoplasm surrounding a large, central vacuole. It is a motile organism through gliding. The trichome diameters of Thioploca araucae range from 30 to 43 μm.

Thioploca chileae

Thioploca chileae is a marine thioploca from the benthos of the Chilean continental shelf. It is a colonial, multicellular, gliding trichomes of similar diameter enclosed by a shared sheath. It possesses cellular sulfur inclusions located in a thin peripheral cytoplasm surrounding a large, central vacuole. It is a motile organism through gliding. The trichome diameters of Thioploca chileae range from 12 to 20 μm.


The Thiotrichaceae are a family of Proteobacteria, including Thiomargarita namibiensis, the largest known bacterium. Some species are movable by gliding, Thiospira by using flagella.

Prokaryotes: Bacteria classification (phyla and orders)
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