The family picrophilaceae

Abstract

The genus Picrophilus is the only described genus of the family Picrophilaceae and is represented by two species, P. torridus and P. oshimae. The only apparent differentiating feature between the two species is their 16S rRNA gene sequences which are 99.45 % similar over 1,460 nucleotides. Given this, it is unlikely that these are two separate species. Picrophilus are nonmotile, irregular cocci and are thermophilic, heterotrophic, obligate aerobes that are hyperacidophilic, growing optimally at 60 °C and pH 0.7. Picrophilaceae differs from Ferroplasmaceae and Thermoplasmaceae in that members of Picrophilaceae have an S-layer. The genome of P. torridus has been sequenced, revealing one of the smallest known genomes of an aerobic free-living heterotrophic archaeon at 1.55 Mb.