Alicyclobacillus acidocaldarius

Alicyclobacillus acidocaldarius is a species of Gram positive, strictly aerobic, bacterium. The bacteria are acidophilic, thermophilic, and produce endospores. The first identified strains of "A. acidocaldarius" were from geysers in Yellowstone National Park and fumerole soil in Hawaii Volcano National Park. The species was originally classified as "Bacillus acidocaldarius" in 1971, but further 16S rRNA studies found that the species belonged in the newly created genus "Alicyclobacillus". The species name is derived from the Latin "acidum" (acid) and "caldarius" (pertaining to warm or hot), referring to the acidic and high temperature environments from which it was first isolated. Thomas D. Brock was one of the researchers who first categorized the species; his discovery of "Thermus aquaticus" allowed for other researchers to discover Taq polymerase and polyermase chain reaction (PCR).
A strain of "A. acidocaldarius" has been isolated from thermally heated soils of Mount Rittmann in Antarctica. 
"A. acidocaldarius" was among the first three species reclassified from the genus "Bacillus" to the newly created "Alicyclobacillus" in 1992, along with "A. acidoterrestris" and "A. cycloheptanicus".
The optimum growth temperature for "A. acidocaldarius" is 60-65 °C, and can grow in the 45-70 °C range. The optimum pH is 3.0-4.0, and can grow in pH 2.0-6.0.