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.
Bacillus cereus is a Gram-positive rod-shaped bacterium commonly found in soil, food, and marine sponges. The specific name, cereus, meaning "waxy" in Latin, refers to the appearance of colonies grown on blood agar. Some strains are harmful to humans and cause foodborne illness due to their spore-forming nature, while other strains can be beneficial as probiotics for animals, and even exhibit mutualism with certain plants. B. cereus bacteria may be anaerobes or facultative anaerobes, and like other members of the genus Bacillus, can produce protective endospores. They have a wide range of virulence factors, including phospholipase C, cereulide, sphingomyelinase, metalloproteases, and cytotoxin K, many of which are regulated via quorum sensing. B. cereus strains exhibit flagellar motility.
Thermus aquaticus is a species of bacteria that can tolerate high temperatures, one of several thermophilic bacteria that belong to the Deinococcota phylum. It is the source of the heat-resistant enzyme Taq DNA polymerase, one of the most important enzymes in molecular biology because of its use in the polymerase chain reaction (PCR) DNA amplification technique.
Serratia is a genus of Gram-negative, facultatively anaerobic, rod-shaped bacteria of the family Enterobacteriaceae. According to the List of Prokaryotic names with Standing Nomenclature (LPSN), there are currently 19 species of Serratia that are credibly published with accurate names as of 2020: S. aquatilis, S. entomophila, S. ficaria, S. fonticola, S. grimesii, S. liquefaciens, S. marcescens, S. microhaemolytica, S. myotis, S. nematodiphila, S. odoriferae, S. oryzae, S. plymuthica, S. proteamaculans, S. quinivorans corrig, S. rubidaea, S. symbiotica, S. ureilytica, S. vespertilionis. They are typically 1–5 μm in length, do not produce spores, and can be found in water, soil, plants, and animals. Some members of this genus produce a characteristic red pigment, prodigiosin, and can be distinguished from other members of the order Enterobacterales by their unique production of three enzymes: DNase (nucA), lipase, and gelatinase (serralysin). Serratia was thought to be a harmless environmental bacteria until it was discovered that the most common species in the genus, S. marcescens, is an opportunistic pathogen of many animals, including humans. In humans, S. marcescens is mostly associated with nosocomial, or hospital-acquired, infections, but can also cause urinary tract infections, pneumonia, and endocarditis. S. marcescens is frequently found in showers, toilet bowls, and around wet tiles as a pinkish to red biofilm but only causes disease in immunocompromised individuals. Aside from S. marcescens, some rare strains of the Serratia species S. plymuthica, S. liquefaciens, S. rubidaea, and S. odoriferae have been shown to cause infection such as osteomyelitis and endocarditis.
The Thermomicrobia is a group of thermophilic green non-sulfur bacteria. Based on species Thermomicrobium roseum and Sphaerobacter thermophilus, this bacteria class has the following description:
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.
Thermus thermophilus is a Gram-negative bacterium used in a range of biotechnological applications, including as a model organism for genetic manipulation, structural genomics, and systems biology. The bacterium is extremely thermophilic, with an optimal growth temperature of about 65 °C (149 °F). Thermus thermophilus was originally isolated from a thermal vent within a hot spring in Izu, Japan by Tairo Oshima and Kazutomo Imahori. The organism has also been found to be important in the degradation of organic materials in the thermogenic phase of composting. T. thermophilus is classified into several strains, of which HB8 and HB27 are the most commonly used in laboratory environments. Genome analyses of these strains were independently completed in 2004. Thermus also displays the highest frequencies of natural transformation known to date.
Bacteroides fragilis is an anaerobic, Gram-negative, pleomorphic to rod-shaped bacterium. It is part of the normal microbiota of the human colon and is generally commensal, but can cause infection if displaced into the bloodstream or surrounding tissue following surgery, disease, or trauma.
Bacillus licheniformis is a bacterium commonly found in the soil. It is found on bird feathers, especially chest and back plumage, and most often in ground-dwelling birds and aquatic species.
"Aromatoleum" is a genus of bacteria capable of microbial biodegradation of organic pollutants. It has one single described species member, A. aromaticum, for which the only strain is strain EbN1.
Keratinases are proteolytic enzymes that digest keratin.
Thermotoga neapolitana is a hyperthermophilic organism that is a member of the order Thermotogales.
Thermotoga hypogea is a hyperthermophilic organism that is a member of the order Thermotogales. It is thermophilic, xylanolytic, glucose-fermenting, strictly anaerobic and rod-shaped. The type strain of T. hypogea is SEBR 7054.
Thermotoga petrophila is a hyperthermophilic, anaerobic, non-spore-forming, rod-shaped, fermentative heterotroph, with type strain RKU-1T. T. petrophila was first discovered and isolated from an oil reservoir off of the coast of Japan and was deemed genetically distinct from its sister clades. Because these organism are found in deep, hot aquatic settings, they have become of great interest for biotechnology due to their enzymes functioning at high temperatures and pressures.
Fervidobacterium gondwanense is a species of thermophilic anaerobic bacteria. It is non-sporulating, motile, gram-negative, and rod-shaped. F. godwanense was isolated in Great Artesian basin in Australia from non-volcanicly heated geothermal waters.
Fervidobacterium changbaicum is a species of thermophilic anaerobic bacteria. It is non-sporulating, motile, gram-negative, and rod-shaped. The type strain is CBS-1(T).
Spirochaeta thermophila is a fairly recently discovered free-living, anaerobic, spirochaete that seems to be the most thermophilic of the Spirochaetales order. The type species was discovered in 1992 in Kuril islands, Russia and described in Aksenova, et al. It has been isolated in the sediments and water columns of brackish aquatic habitats of various ponds, lakes, rivers, and oceans. This organism is identified as a new species based on its unique ability to degrade cellulose, xylan, and other α- and β-linked sugars and use them as the sole carbon source by encoding many glycoside hydrolases. It is presumed to secrete cellulases to break down plant-matter around it but there has been little work on the characterization of the enzymes responsible for this.
Polaribacter is a genus in the family Flavobacteriaceae. They are gram-negative, aerobic bacteria that can be heterotrophic, psychrophilic or mesophilic. Most species are non-motile and species range from ovoid to rod-shaped. Polaribacter forms yellow- to orange-pigmented colonies. They have been mostly adapted to cool marine ecosystems, and their optimal growth range is at a temperature between 10 and 32 °C and at a pH of 7.0 to 8.0. They are oxidase and catalase-positive and are able to grow using carbohydrates, amino acids, and organic acids.
Effusibacillus pohliae is a species of Gram positive, aerobic, thermophilic bacterium. The cells are rod-shaped and form spores. It was first isolated from Mount Melbourne, Antarctica. The species is named after the genus of Pohlia nutans, a species of moss that was colonizing the area where the type strain was isolated. E. pohliae has also been isolated from a geothermal heat pump in South Korea.
Cytophagales is an order of non-spore forming, rod-shaped, Gram-negative bacteria that move through a gliding or flexing motion. These chemoorganotrophs are important remineralizers of organic materials into micronutrients. They are widely dispersed in the environment, found in ecosystems including soil, freshwater, seawater and sea ice. Cytophagales is included in the Bacteroidota phylum.
