ABSTRACT
Bacteria of the genus Thermus were first isolated from hot springs in Yellowstone National Park, US at temperatures of 53 to 86°C and pH values between 8 and 9, and allocated to the type species, Thermus aquaticus. A low concentration of organic matter in the medium, together with an incubation temperature of 70 to 75°C, was emphasized as important for the isolation of T. aquaticus. The definition of Thermus as Gram-negative is open to doubt for a number of reasons, despite the cell wall structure and the mode of cell division by invagination rather than septum formation in the Gram-positive manner. The taxonomic position of Thermus relative to other genera remains uncertain, but a catalogue of oligonucleotides derived from 16S RNA has been claimed to indicate a remote but distinct relationship between Thermus. Strains of the genus Thermus are sources of several restriction endonucleases that are both thermostable and active at higher temperatures than most other such enzymes.
