Hydrogenophilaceae

The Hydrogenophilaceae are a family of the Hydrogenophilalia, with two genera – Hydrogenophilus and Tepidiphilus. Like all "Proteobacteria", they are Gram-negative. All known species are thermophilic, growing around 50 °C and using molecular hydrogen or organic molecules as their source of electrons to support growth - some species are autotrophs.

The genus Thiobacillus was previously considered to be a member in this family but was reclassified into the order Nitrosomonadales at the same time that the Hydrogenophilales were removed from the Betaproteobacteria and the class Hydrogenophilalia was formed.[2]

Hydrogenophilus thermoluteolus is a facultative chemolithoautotroph originally isolated from a hot spring; however, it was detected 2004 in ice core samples retrieved from a depth around 3 km within the ice covering Lake Vostok in Antarctica.[3] The presence of DNA from (and potentially live cells of) thermophilic bacteria in the ice suggests that a geothermal system could exist beneath the cold water body of Lake Vostok, or simply that non-thermophilic strains of Hydrogenophilus exist and were present in the ice.