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The Hydrogenophilaceae are a family of Betaproteobacteria
Betaproteobacteria is a class of Proteobacteria. Betaproteobacteria are, like all Proteobacteria, gram-negative.The Betaproteobacteria consist of several groups of aerobic or facultative bacteria which are often highly versatile in their degradation capacities, but also contain chemolithotrophic...

, with two genera. Like all Proteobacteria
The Proteobacteria are a major group of bacteria. They include a wide variety of pathogens, such as Escherichia, Salmonella, Vibrio, Helicobacter, and many other notable genera....

 they are Gram-negative
Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...

. Hydrogenophilus are thermophilic
A thermophile is an organism — a type of extremophile — that thrives at relatively high temperatures, between 45 and 122  °C . Many thermophiles are archaea...

, growing around 50 °C and obtaining their energy from oxidizing hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

. It includes the genera Hydrogenophilus and Thiobacillus (see below for the removal of certain species).

Thiobacillus spp. can be used in pest control
Pest control
Pest control refers to the regulation or management of a species defined as a pest, usually because it is perceived to be detrimental to a person's health, the ecology or the economy.-History:...

, such as potato scabs. If an affected area is treated with sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 and Thiobacillus spp., the bacteria will oxidise the sulfur to sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

, which will destroy the pest, as the potato scabs cannot tolerate acidic conditions. Thiobacillus thioparus may contribute to the formation of acid rain through the oxidation of sulfur dioxide
Sulfur dioxide
Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...

 to sulfurous acid
Sulfurous acid
Sulfurous acid is the chemical compound with the formula H2SO3. There is no evidence that sulfurous acid exists in solution, but the molecule has been detected in the gas phase...


Hydrogenophilus thermoluteolus is a facultative chemolithoautotroph that previously had only been found in hot spring
Hot spring
A hot spring is a spring that is produced by the emergence of geothermally heated groundwater from the Earth's crust. There are geothermal hot springs in many locations all over the crust of the earth.-Definitions:...

s. However, it was isolated in 2004 from ice core samples retrieved from a depth of ~3km under the ice layer covering Lake Vostok
Lake Vostok
Lake Vostok is the largest of more than 140 subglacial lakes found under the surface of Antarctica. The overlying ice provides a continuous paleoclimatic record of 400,000 years, although the lake water itself may have been isolated for 15 to 25 million years. The lake is named after the...

 in Antarctica. The presence of this thermophilic bacteria in the ice suggests that a geothermal
Geothermal is related to energy and may refer to:* The geothermal gradient and associated heat flows from within the Earth- Renewable technology :...

 system exists beneath the cold water body of Lake Vostok.

Obsolete Thiobacillus species

The genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Thiobacillus, was redefined to include only those species included among the Betaproteobacteria. Other member organisms once named "Thiobacillus" were transferred to Gammaproteobacteria
Gammaproteobacteria is a class of several medically, ecologically and scientifically important groups of bacteria, such as the Enterobacteriaceae , Vibrionaceae and Pseudomonadaceae. An exceeding number of important pathogens belongs to this class, e.g...

  • "Thiobacillus thiooxidans" was moved to Acidithiobacillus
    Acidithiobacillus is a genus of Proteobacteria. Like all Proteobacteria, Acidithiobacillus is Gram-negative. The members of this genus used to belong to Thiobacillus, before they were reclassified in the year 2000....

  • "Thiobacillus neapolitanus" was moved to Halothiobacillus
    Halothiobacillus is a genus of Proteobacteria. All species are obligate aerobic bacteria, they requires oxygen to grow. They are also halophile, they live in environments with high concentrations of salt....

  • "Thiobacillus tepidarius" was moved to Thermithiobacillus
    Thermithiobacillus is a genus of non-sporeforming rod proteobacteria . The name derives from the Latin thermae, for warm baths, and the Greek thios for sulfur. The members of this genus used to belong to Thiobacillus, before they were reclassified on the basis of 16S rRNA analysis in 2000...