Aquifex pyrophilus is a gram-negative, non-spore forming, rod-shaped bacteria. It is one of a handful of species in the Aquificota phylum, which are a group of thermophilic bacteria that are found near underwater volcanoes or hot springs.
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 of 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 H
2 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.
The Alicyclobacillaceae are a family of Gram-positive bacteria. All members of this family are aerobic and form endospores.
Ferroplasma is a genus of Archaea that belong to the family Ferroplasmaceae. Members of the Ferroplasma are typically acidophillic, pleomorphic, irregularly shaped cocci.
Hydrogen-oxidizing bacteria are a group of facultative autotrophs that can use hydrogen as an electron donor. They can be divided into aerobes and anaerobes. The former use hydrogen as an electron donor and oxygen as an acceptor while the latter use sulphate or nitrogen dioxide as electron acceptors. Species of both types have been isolated from a variety of environments, including fresh waters, sediments, soils, activated sludge, hot springs, hydrothermal vents and percolating water.
Hydrogenobacter thermophilus is an extremely thermophilic, straight rod (bacillus) bacterium. TK-6 is the type strain for this species. It is a Gram negative, non-motile, obligate chemolithoautotroph. It belongs to one of the earliest branching order of Bacteria. H. thermophilus TK-6 lives in soil that contains hot water. It was one of the first hydrogen oxidizing bacteria described leading to the discovery, and subsequent examination of many unique proteins involved in its metabolism. Its discovery contradicted the idea that no obligate hydrogen oxidizing bacteria existed, leading to a new understanding of this physiological group. Additionally, H. thermophilus contains a fatty acid composition that had not been observed before.
Acidithiobacillus caldus formerly belonged to the genus Thiobacillus prior to 2000, when it was reclassified along with a number of other bacterial species into one of three new genera that better categorize sulfur-oxidizing acidophiles. As a member of the Gammaproteobacteria class of Pseudomonadota, A. caldus may be identified as a Gram-negative bacterium that is frequently found in pairs. Considered to be one of the most common microbes involved in biomining, it is capable of oxidizing reduced inorganic sulfur compounds (RISCs) that form during the breakdown of sulfide minerals. The meaning of the prefix acidi- in the name Acidithiobacillus comes from the Latin word acidus, signifying that members of this genus love a sour, acidic environment. Thio is derived from the Greek word thios and describes the use of sulfur as an energy source, and bacillus describes the shape of these microorganisms, which are small rods. The species name, caldus, is derived from the Latin word for warm or hot, denoting this species' love of a warm environment.
Virgibacillus is a genus of Gram-positive, rod-shaped (bacillus) bacteria and a member of the phylum Bacillota. Virgibacillus species can be obligate aerobes, or facultative anaerobes and catalase enzyme positive. Under stressful environmental conditions, the bacteria can produce oval or ellipsoidal endospores in terminal, or sometimes subterminal, swollen sporangia. The genus was recently reclassified from the genus Bacillus in 1998 following an analysis of the species V. pantothenticus. Subsequently, a number of new species have been discovered or reclassified as Virgibacillus species.
The genus Annwoodia was named in 2017 to circumscribe an organism previously described as a member of the genus Thiobacillus, Thiobacillus aquaesulis - the type and only species is Annwoodia aquaesulis, which was isolated from the geothermal waters of the Roman Baths in the city of Bath in the United Kingdom by Ann P. Wood and Donovan P. Kelly of the University of Warwick - the genus was subsequently named to honour Wood's contribution to microbiology. The genus falls within the family Thiobacillaceae along with Thiobacillus and Sulfuritortus, both of which comprise autotrophic organisms dependent on thiosulfate, other sulfur oxyanions and sulfide as electron donors for chemolithoheterotrophic growth. Whilst Annwoodia spp. and Sulfuritortus spp. are thermophilic, Thiobacillus spp. are mesophilic.
Hydrogenibacillus is a thermophilic and facultatively chemolithoautotrophic genus of bacteria from the family of Bacillaceae with one known species. Bacillus schlegelii was transferred to Hydrogenibacillus schlegelii
Hydrogenibacillus schlegelii is a Gram-positive species of bacteria. Strains of this species were originally isolated from a lake near St-Blaise, Neuchâtel, Switzerland. The species is thermophilic; strains isolated from soil in Antarctica were found to grow at temperatures between 59 and 72 °C.
Alicyclobacillus acidocaldarius is a species of Gram positive, strictly aerobic, bacterium. The bacteria are acidophilic, thermophilic, and produce endospores. The first identified strains of A. acidocaldarius were from geysers in Yellowstone National Park and fumerole soil in Hawaii Volcano National Park. The species was originally classified as Bacillus acidocaldarius in 1971, but further 16S rRNA studies found that the species belonged in the newly created genus Alicyclobacillus. The species name is derived from the Latin acidum (acid) and caldarius, referring to the acidic and high temperature environments from which it was first isolated. Thomas D. Brock was one of the researchers who first categorized the species; his discovery of Thermus aquaticus allowed for other researchers to discover Taq polymerase and polyermase chain reaction (PCR).
Kyrpidia is a genus of Gram-positive, rod-shaped, thermophilic, spore-forming bacteria.
Kyrpidia spormannii is a species of Gram positive, aerobic, thermophilic bacterium. The cells are rod-shaped and form spores. It was first isolated from sediment samples from hydrothermal systems collected in the Azores. The species is named in honor of German-American microbiologist Alfred M. Spormann, in recognition of his work on the field microbial electrosynthesis.
Effusibacillus lacus is a species of Gram positive, facultatively anaerobic, thermophilic bacterium. The cells are rod-shaped and form spores. It was first isolated from freshwater lake sediment from Lake Mizugaki, Japan. The species name is derived from lacus.
Alkalihalobacillus is a genus of gram-positive or gram-variable rod-shaped bacteria in the family Bacillaceae from the order Bacillales. The type species of this genus is Alkalihalobacillus alcalophilus.
Neobacillus is a genus of rod-shaped bacteria that show Gram-positive or Gram-variable staining. This genus belongs under the family Bacillaceae within the order Bacillales. The type species of Neobacillus is Neobacillus niacini.
Cytobacillus is a genus of rod-shaped bacteria that stain either Gram-positive or Gram-variable in the family Bacillaceae within the order Bacillales. The type species for this genus is Cytobacillus firmus.
Peribacillus is a genus of rod-shaped bacteria that exhibits Gram-positive or Gram-variable staining that belongs in the family Bacillaceae within the order Bacillales. The type species for this genus is Peribacillus simplex.
Ferdinandcohnia is a genus of rod-shaped bacteria that generally display Gram-positive staining in the family Bacillaceae within the order Bacillales. The type species for this genus is Ferdinandcohnia humi.
