Pseudomonadota is a major phylum of Gram-negative bacteria. The renaming of several prokaryote phyla in 2021, including Pseudomonadota, remains controversial among microbiologists, many of whom continue to use the earlier name Proteobacteria, of long standing in the literature. The phylum Proteobacteria includes a wide variety of pathogenic genera, such as Escherichia, Salmonella, Vibrio, Yersinia, Legionella, and many others. Others are free-living (non-parasitic) and include many of the bacteria responsible for nitrogen fixation.
The Hydrogenophilaceae are a family of the Hydrogenophilalia, with two genera – Hydrogenophilus and Tepidiphilus. Like all Pseudomonadota, they are Gram-negative. All known species are thermophilic, growing around 50 °C and using molecular hydrogen or organic molecules as their source of electrons to support growth - some species are autotrophs.
Thiobacillus is a genus of Gram-negative Betaproteobacteria. Thiobacillus thioparus is the type species of the genus, and the type strain thereof is the StarkeyT strain, isolated by Robert Starkey in the 1930s from a field at Rutgers University in the United States of America. While over 30 "species" have been named in this genus since it was defined by Martinus Beijerinck in 1904,, most names were never validly or effectively published. The remainder were either reclassified into Paracoccus, Starkeya ; Sulfuriferula, Annwoodia, Thiomonas ; Halothiobacillus, Guyparkeria, or Thermithiobacillus or Acidithiobacillus. The very loosely defined "species" Thiobacillus trautweinii was where sulfur oxidising heterotrophs and chemolithoheterotrophs were assigned in the 1910-1960s era, most of which were probably Pseudomonas species. Many species named in this genus were never deposited in service collections and have been lost.
The Acidithiobacillales are an order of bacteria within the class Acidithiobacillia and comprises the genera Acidithiobacillus and Thermithiobacillus. Originally, both were included in the genus Thiobacillus, but they are not related to the type species, which belongs to the Betaproteobacteria.
Acidithiobacillus is a genus of the Acidithiobacillia in the phylum "Pseudomonadota". This genus includes ten species of acidophilic microorganisms capable of sulfur and/or iron oxidation: Acidithiobacillus albertensis, Acidithiobacillus caldus, Acidithiobacillus cuprithermicus, Acidithiobacillus ferrianus, Acidithiobacillus ferridurans, Acidithiobacillus ferriphilus, Acidithiobacillus ferrivorans, Acidithiobacillus ferrooxidans, Acidithiobacillus sulfuriphilus, and Acidithiobacillus thiooxidans.A. ferooxidans is the most widely studied of the genus, but A. caldus and A. thiooxidans are also significant in research. Like all "Pseudomonadota", Acidithiobacillus spp. are Gram-negative and non-spore forming. They also play a significant role in the generation of acid mine drainage; a major global environmental challenge within the mining industry. Some species of Acidithiobacillus are utilized in bioleaching and biomining. A portion of the genes that support the survival of these bacteria in acidic environments are presumed to have been obtained by horizontal gene transfer.
Halothiobacillus is a genus in the Gammaproteobacteria. Both species are obligate aerobic bacteria; they require oxygen to grow. They are also halotolerant; they live in environments with high concentrations of salt or other solutes, but don't require them in order to grow.
Thermithiobacillus is a genus of nonsporeforming, rod-shaped, Gram-negative bacteria. The name derives from the Latin thermae, for warm baths, and the Classical Greek θείος, theios for sulfur. The type species of this genus was previously assigned to the genus Thiobacillus, but it was reclassified on the basis of 16S rRNA analysis in 2000, creating this genus.
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.
Ferroplasma is a genus of Archaea that belong to the family Ferroplasmaceae. Members of the Ferroplasma are typically acidophillic, pleomorphic, irregularly shaped cocci.
The outflow of acidic liquids and other pollutants from mines is often catalysed by acid-loving microorganisms; these are the acidophiles in acid mine drainage.
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
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.
Acidithiobacillus thiooxidans, formerly known as Thiobacillus thiooxidans until its reclassification into the newly designated genus Acidithiobacillus of the Acidithiobacillia subclass of Pseudomonadota, is a Gram-negative, rod-shaped bacterium that uses sulfur as its primary energy source. It is mesophilic, with a temperature optimum of 28 °C. This bacterium is commonly found in soil, sewer pipes, and cave biofilms called snottites. A. thiooxidans is used in the mining technique known as bioleaching, where metals are extracted from their ores through the action of microbes.
Metallosphaera sedula is a species of Metallosphaera that is originally isolated from a volcanic field in Italy. Metallosphaera sedula can be roughly translated into “metal mobilizing sphere” with the word “sedulus” meaning busy, describing its efficiency in mobilizing metals. M. sedula is a highly thermoacidophilic Archaean that is unusually tolerant of heavy metals.
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.
Guyparkeria is a genus in the Gammaproteobacteria. Both species are obligate aerobic bacteria; they require oxygen to grow. They are also halophilic and have varying degrees of thermophilicity. They live in environments with high concentrations of salt or other solutes, such as in hydrothermal vent plumes or in hypersaline playas, and do require high sodium ion concentrations in order to grow, as is also the case in the other genus of the same family, Thioalkalibacter
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 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).
Sulfobacillus thermosulfidooxidans is a species of bacteria of the genus Sulfobacillus. It is an acidophilic, mixotrophic, moderately thermophilic, Gram-positive, sporulating facultative anaerobe. As its name suggests, it is capable of oxidizing sulfur.
Deferrisoma camini is a moderately thermophilic and anaerobic bacterium from the genus of Deferrisoma which has been isolated from a deep-sea hydrothermal vent from the Eastern Lau Spreading Centre in the Pacific Ocean.
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.
