In taxonomy

Alpha taxonomy

Alpha taxonomy is the discipline concerned with finding, describing and naming species of living or fossil organisms. This field is supported by institutions holding collections of these organisms, with relevant data, carefully curated: such institutes include natural history museums, herbaria and...

, Picrophilus is an archaea

Archaea

The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon...

n genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of the family Picrophilaceae

Picrophilaceae

In taxonomy, the Picrophilaceae are a family of the Thermoplasmatales.-External links:...

.

Picrophilus is an extremely acidophilic

Acidophile (organisms)

Acidophilic organisms are those that thrive under highly acidic conditions . These organisms can be found in different branches of the tree of life, including Archaea, Bacteria, and Eukaryotes...

 genus within Euryarchaeota

Euryarchaeota

In the taxonomy of microorganisms, the Euryarchaeota are a phylum of the Archaea.The Euryarchaeota include the methanogens, which produce methane and are often found in intestines, the halobacteria, which survive extreme concentrations of salt, and some extremely thermophilic aerobes and anaerobes...

. These microbes are the most acidophilic

Acidophile (organisms)

Acidophilic organisms are those that thrive under highly acidic conditions . These organisms can be found in different branches of the tree of life, including Archaea, Bacteria, and Eukaryotes...

 organisms currently known, with the ability to grow at a pH of -0.06. They are obligate acidophile

Acidophile (organisms)

Acidophilic organisms are those that thrive under highly acidic conditions . These organisms can be found in different branches of the tree of life, including Archaea, Bacteria, and Eukaryotes...

s and are unable to maintain their membrane integrity at pH values higher than 4. While phylogenetically related to other organisms within Thermoplasmata

Thermoplasmata

In taxonomy, the Thermoplasmata are a class of the Euryarchaeota.All are acidophiles, growing optimally at pH below 2. Picrophilus is currently the most acidophilic of all known organisms growing at a minimum pH of 0.06. Many of these organisms do not contain a cell wall, although this is not true...

, unlike Thermoplasma

Thermoplasma

In taxonomy, Thermoplasma is a genus of the Thermoplasmataceae.Thermoplasma is a genus of archaea. It belongs to the Thermoplasmata, which thrive in acidic and high-temperature environments. Thermoplasma are facultative anaerobes and respire using sulfur and organic carbon...

and Ferroplasma

Ferroplasma

In taxonomy, Ferroplasma is a genus of the Ferroplasmaceae.The genus Ferroplasma consists solely of F. acidophilum, an acidophilic iron-oxidizing member of the Euryarchaeota. Unlike other members of the Thermoplasmata F.acidophilum is a mesophile with a temperature optimum of approximately 35°C, at...

, Picrophilus contains an S-layer

S-layer

An S-layer is a part of the cell envelope commonly found in bacteria, as well as among archaea.It consists of a monomolecular layer composed of identical proteins or glycoproteins. This two-dimensional structure is built via self-assembly and encloses the whole cell surface. Thus, the S-layer...

cell wall.

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