Any of a group of single-celled prokaryotic species (i.e., organisms without a distinct nucleus) with molecular characteristics that separate them from bacteria (the other, more prominent group of prokaryotes) and eukaryotes. The word archaea comes from the Greek word archaios, which means “ancient” or “primitive,” and some archaea do have characteristics that fit this definition.
Unicellular prokaryotic organisms belong to the Archaea domain. They were previously known as archaebacteria. They differ from bacteria in that their cell walls are made up of distinct components. They can be found in a variety of severe environments, including hot springs, marshy places, and extremely saline areas. They are classified as thermoacidophiles, methanogens, or halophiles depending on their habitat.
These Archaea can be found in a wide variety of habitats. In many species, they make up the microbiota. They can be found in the gut, skin, and mouth of people. They play an essential role in the ecosystem, performing tasks such as carbon fixation, nutrient recycling, and decomposition, among others.
Archaea is a phylum of bacteria that includes both aerobic and anaerobic species that can live in both common and harsh conditions, such as dirt.
Archaebacteria Characteristics: The following are some of archaebacteria’s most notable characteristics:
- Only archaebacteria can undergo methanogenesis because they are obligate or facultative anaerobes, meaning they thrive in the absence of oxygen.
- Lipids make up the walls of Archaebacteria cells.
- The Archaebacteria’s stiff cell wall gives them shape and support. Under hypotonic conditions, it also prevents the cell from bursting.
- Pseudomurein is a component of the cell wall that protects archaebacteria against the effects of Lysozyme. The immune system of the host produces lysozyme, which destroys the cell walls of dangerous bacteria.
- Its dense cytoplasm contains all of the components required for feeding and metabolism.
- Extremophiles are organisms that can live in a wide range of settings. They can survive in both acidic and alkaline water, as well as at degrees over boiling.
- They are capable of withstanding pressures of over 200 atmospheres.
- Archaebacteria are antibiotic-resistant due to the presence of plasmids containing antibiotic resistance enzymes.
- Asexual reproduction, often known as binary fission, is the mode of reproduction.
- They carry out one-of-a-kind gene transcription.
- Because of alterations in their ribosomal RNA, they split from both prokaryotes and eukaryotes.
TYPES OF ARCHAEA
Methanogens
They’re obligate anaerobes, which means they can’t live without oxygen. They can be found in marshy places and in the guts of numerous ruminants. Methane is produced by them. They are commercially utilised to produce biogas (methane) from the fasces of these animals. Methanobacterium, Methanococcus, and so on. They are also found in the human gut and are the cause of flatulence. They are crucial in the treatment of anaerobic wastewater. They come in two shapes: spherical and rod-shaped. In most cases, they are unable to survive in the presence of oxygen. They may have a pseudopeptidoglycan cell wall or an S-layer made up of surface proteins. Methanogens make methane from carbon dioxide, methanol, and methylamines, among other things.
Thermoacidophiles
Extreme temperatures and highly acidic environments are not a problem for these plants. Deep-sea vents and hot Sulphur springs are where they reside. They can withstand both high temperatures and low PH. Their membranes include branched-chain lipids. Thermoplasma is an example of a facultative anaerobe that gets its energy from Sulphur or organic carbon. Thermoproteus is an anaerobe that feeds on hydrogen and Sulphur. Sulphur is reduced by them.
Halophiles
They grow in areas where there is a lot of salt. For example, Halobacterium and Halo coccus. They are members of the Halobacteriaceae family. The presence of unique kinds of lipids in the membrane and mucilage coating protects them in a very acidic environment. There is no plasmolysis and they have a high internal salt concentration. The red carotenoid pigment in their cell membrane protects them from harmful sun radiation.
ARCHAEA DOMAIN
Crenarchaeota
Hyperthermophiles and thermoacidophiles make up the majority of Crenarchaeote. Microorganisms that are hyperthermophiles dwell in extremely hot or cold conditions. Microorganisms known as thermoacidophiles exist in highly hot and acidic conditions. The pH of their surroundings varies between 5 and 1. These species can be found in hydrothermal vents and hot springs.
Crenarchaeotans include the following:
- Sulfolobus acidocaldarius – found in sulphur-rich hot, acidic springs near volcanic areas.
- Pyrolobus fumarii – can withstand temperatures ranging from 90 to 113 degrees Celsius.
Euryarchaeota
Extreme halophiles and methanogens make up the majority of Euryarchaeota species. Extreme halophilic organisms live in salty habitats. They need salty environments to survive. These species can be found in salt lakes or regions where sea water has drained. To exist, methanogens demand an oxygen-free environment (anaerobic). As a result of metabolism, they release methane gas. These creatures can be found in a variety of places, including swamps, marshes, ice lakes, animal stomachs (cows, deer, and people), and sewage.
Examples of Euryarchaeotans include:
- Halobacterium is a genus of halophilic organisms that can be observed in salt lakes and high-salinity ocean regions.
- Methanococcus – Methanococcus jannaschii was the first genetically sequenced Archaean. This methanogen lives near hydrothermal vents.
- Methanococcoides burtonii is a psychrophilic (cold-loving) methanogen that has been identified in Antarctica and can endure freezing conditions.
Korarchaeota
Korarchaeota creatures are regarded to be quite primitive. The major properties of these species are yet unknown. They are thermophilic, as evidenced by their presence in hot springs and obsidian pools.
CONCLUSION
Archaea are fascinating species since they share genes with both bacteria and eukaryotes. Archaea and bacteria are assumed to have evolved independently from a shared ancestor from a phylogenetic standpoint.