A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between 41 and 122 °C. Many thermophiles are archaea, though some of them are bacteria and fungi. Thermophilic eubacteria are suggested to have been among the earliest bacteria.
Methanocaldococcus formerly known as Methanococcus is a genus of coccoid methanogen archaea. They are all mesophiles, except the thermophilic M. thermolithotrophicus and the hyperthermophilic M. jannaschii. The latter was discovered at the base of a “white smoker” chimney at 21°N on the East Pacific Rise and it was the first archaean genome to be completely sequenced, revealing many novel and eukaryote-like elements.
Sulfurisphaera is a genus of the Sulfolobaceae.
In taxonomy, Desulfurococcus is a genus of the Desulfurococcaceae.
Thermodiscus is a genus of archaea in the family Desulfurococcaceae. The only species is Thermodiscus maritimus.
In taxonomy, Methanohalobium is a genus of the Methanosarcinaceae. Its genome has been sequenced. The genus contains one species, M. evestigatum.
In taxonomy, Methanomethylovorans is a genus of microorganisms with the family Methanosarcinaceae. This genus was first described in 1999. The species within it generally live in freshwater environments, including rice paddies, freshwater sediments and contaminated soil. They produce methane from methanol, methylamines, dimethyl sulfide and methanethiol. With the exception of M. thermophila, which has an optimal growth temperature of 50 °C, these species are mesophiles and do not tend to grow at temperatures above 40 °C.
Methanobacterium is a genus of the Methanobacteriaceae family of Archaea. Despite the name, this genus belongs not to the bacterial domain but the archaeal domain. Methanobacterium are nonmotile and live without oxygen. Some members of this genus can use formate to reduce methane; others live exclusively through the reduction of carbon dioxide with hydrogen. They are ubiquitous in some hot, low-oxygen environments, such as anaerobic digestors, their wastewater, and hot springs.
Methanothermobacter is a genus of archaeans in the family Methanobacteriaceae. The species within this genus are thermophilic and grow best at temperatures between 55 °C and 65 °C. They are methanogens; they use carbon dioxide and hydrogen as substrates to produce methane for energy.
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
Moorella is a genus of bacteria belonging to the phylum Bacillota.
Methanothermus fervidus is a species of methanogen. It is notable for being extremely thermophilic. Its cells are rod-shaped; its complex cell envelope exhibits two layers, each about 12 nm thick; the inner represents the pseudomurein sacculus and the outer a protein envelope. The type strain is Methanothermus fervidus Stetter 1982. The cells are motile, strictly anaerobic and stain Gram positive. They can grow at temperatures as high as 97 °C. Strain V24ST can subsist on carbon dioxide and hydrogen alone. Its genome is 1,243,342 bp in length.
The Natranaerobiales are an order of bacteria placed within the class Clostridia. This order contains the thermophilic bacterial species Natranaerobius thermophilus and the related species Natranaerobaculum magadiense.
Pelotomaculum is a Gram-positive strictly anaerobic, mesophilic, thermophilic and non-motile bacterial genus from the family of Peptococcaceae.
Carboxydocella is a Gram-positive and obligate anaerobe bacterial genus from the family of Syntrophomonadaceae.
Caldanaerobacter is a Gram-positive or negative and strictly anaerobic genus of bacteria from the family of Thermoanaerobacteraceae.
Caldanaerobius is a genus of thermophilic, obligately anaerobic bacteria from the family of Thermoanaerobacteraceae.
Carboxydothermus is a genus of thermophilic, anaerobic bacteria from the family of Thermoanaerobacteraceae.
Atribacterota is a phylum of bacteria, which are common in anoxic sediments rich in methane. They are distributed worldwide and in some cases abundant in anaerobic marine sediments, geothermal springs, and oil deposits. Genetic analyzes suggest a heterotrophic metabolism that gives rise to fermentation products such as acetate, ethanol, and CO2. These products in turn can support methanogens within the sediment microbial community and explain the frequent occurrence of Atribacterota in methane-rich anoxic sediments. According to phylogenetic analysis, Atribacterota appears to be related to several thermophilic phyla within Terrabacteria or may be in the base of Gracilicutes. According to research, Atribacterota shows patterns of gene expressions which consists of fermentative, acetogenic metabolism. These expressions let Atribacterota to be able to create catabolic and anabolic functions which are necessary to generate cellular reproduction, even when the energy levels are limited due to the depletion of dissolved oxygen in the areas of sea waters, fresh waters, or ground waters.
The Ignavibacteriales are an order of obligately anaerobic, non-photosynthetic bacteria that are closely related to the green sulfur bacteria.
