Thermoacidophile

A thermoacidophile is an extremophilic microorganism that is both thermophilic and acidophilic; i.e., it can grow under conditions of high temperature and low pH.

[1] The large majority of thermoacidophiles are archaea (particularly the Thermoproteota and "Euryarchaeota") or bacteria, though occasional eukaryotic examples have been reported.

The conversion of reduced sulfides to oxidized sulfates leads to a production of protons, lowering the pH[1] of the surrounding environment.

While reduced sulfides are generally considered to be reactive, their conversion to their oxidized counterpart by abiotic natural processes (reacting with things that are not living organisms) is relatively low.

[1] Adaptations that allow them to survive in these harsh environments include proton pumps and buffering strategies, epigenetic modifications of the chromosome, and altered membrane structures.

[8] Chromatin proteins are used to condense and organize the genome, however this is not done with histone-orthologs as in eukaryotes or some bacteria, a large evolutionary divergence that characterizes thermoacidophilic archaea.

[10] The A compartment generally contains genes involved in essential biological processes such as the creation of metabolic proteins, which are highly expressed in the cell.

The B compartment holds genes related to environmental stress responses, CRISPR-Cas clusters and fatty acid metabolism.

While these mechanisms are not necessarily unique to thermoacidophiles and can be found in thermophiles and acidophiles respectively, their incorporation into a single organism can lead to synergistic effects.

For example, while DNA stability does not necessarily depend solely on its base pair composition, some thermoacidophiles favor the AGG and AGA codons over CGN for arginine.

Additionally, thermoacidophiles tend to avoid using amino acids that participate in unwanted side reactions at high temperatures, including histidine, glutamine and threonine.