Thermoplasma acidophilum

From MicrobeWiki, the student-edited microbiology resource

A Microbial Biorealm page on the genus Thermoplasma acidophilum


Higher order taxa

Cellular organisms;Archaea; Euryarchaeota; Thermoplasmata; Thermoplasmatales; Thermoplasmataceae; Thermoplasma acidophilum (1)


Thermoplasma acidophilum

NCBI: Taxonomy

Description and significance

Thermoplasma acidophilum. Linda Stannard, UCT/Photo Science Library.

'Thermoplasma acidophilum' is a thermophilic heterotrophic prokaryote, they usually grow in mass colony covered in their “S-layer”. “Thermoplasma acidophilum is among the most acidophilic organism known.” They grow at 55-60°C and favor a really low pH of 0.5-4; (2) It is found and first isolated from self-heating coal refuse piles and solfatara fields. (3)

“Microbial physiologists and structural biologists have long been fascinated by the ability of this microorganism to grow at high temperatures and low pH without the structural protection of a conventional cell wall”, they are specially interest in the protein these organism have because common protein get denature under the acidic and hot environment Thermoplasma acidophilum live in. By determining and studying the genome sequence of this organism, we can have better understanding in protein folding and degration which led to seek more complete representation of the proteins involved in different metabolic pathways. (3)

Genome structure




Although the characteristics of Thermoplasma acidophilum’s small genome identify these organism as a“typical euryarchaeon with a substantial complement of bacterial-related genes.” However,“massive lateral gene transfer appears to have occurred between Thermoplasma and Sulfolobus solfataricus, a phylogenetically distant crenarchaeon inhabiting the same environment.” (2)

Cell structure and metabolism

Species of the genus Thermoplasma lack rigid cell wall, but are only delimited by a plasma membrane, it is “devoid of protective outer shells (S-layer, cell wall), yet maintains a near-neutral cytosolic pH.” (4)

The lipid composition of T. acidophilum has brought to attentions in recent research and has been the subject of several investigations. This work has revealed the presence of “large polar lipids, often glycosylated with glucose, mannose and gulose, phosphorylated, or both, forming phosphoglycolipids” (5). These unusual lipid compositions allow T.acidophilum to survive under the harsh conditions of temperature and pH“restructing proton flow across the membrane more efficiently than non-branched lipids (6)”

Thermoplasma acidophilum is able to gain energy in several ways, either anaerobically by sulphur respiration or as a scavenger in extreme environment. In Thermoplasma, glucose degradation is done by a “non-phosphorylated variant of the Entner–Doudoroff pathway, in which the first step is catalysed by glucose dehydrogenase.” Acetyl-CoA produced from this pathway enters theTCA cycle. (the presence of enzyme require for this pathway had already been experimentally confirmed), the presence of glycolysis/gluconeogenesis has not yet been confirmed due to the absence of phosphofructokinase and fructose in this organism. (7)


Thermoplasma acidophilum plays an important role in the ecosystem, they act as scavenger of those extreme environment. “It has adapted to scavenging nutrients from the decomposition of organisms killed by the extreme acidity and requires yeast, bacterial or meat extract when grown in culture.” (3)

The study and research on Thermoplasma acidophilum indicate that an aqueous extract of coal refuse will serve as a nutrient source this is the first step leading to the discovery of the materials in coal refuse which support its growth. Indeed, the coal refuse material provides nutrients for the growth of a wide variety of microorganisms and could be a source of new growth factors. (8)


None of the archaea organism include Thermoplasma acidophilum had known to cause pathogen to human being.

Application to Biotechnology

The 20S proteasome from T.acidophilum has brought to attention by scientist recently because it's proteolytic mechanism is common between the archaebacterial and the eukaryotic forms of the enzyme which is clinically relavent. (9)

In higher eukaryotes, proteasome is involved in housekeeping and protein level regulation. Further understand of chemical mechanism of this enzyme can help us to understand disease cause by the mutation of protesomes such as cystic fibrosis, Angelman's syndrome, Parkinson's disease and Liddle syndrome (10).


Current Research

1) “Large chunks of DNA which have been borrowed from other species of microbe and incorporated into the chromosome of acidophilum. The genes are believed to come from microbes and bacteria that share the same environmental niches, like the soil near hydrothermal sites.” (11) The main purpose of this kind of research is to have better understanding of how different microbe evolved and how these related to higher eukaryotes like humans.

2) Ubiquitin found in the archaebacterium Thermoplasma acidophilum strongly suggests that ATP-ubiquitin-dependent proteolysis is a cellular function that developed early in evolution. (13)

3) Tremendous amount of research had been made on 20S proteasome of T.acidophilum, because this enzyme is common in higher eukaryotic organism and can play an important role on medical research. (12) Scientist are trying to find a way to dyregulate this enzymatic system which might help to suppress or cure cancer.
















Edited by student of Rachel Larsen and Kit Pogliano