What kind of environments do archaea live in

Methods such as metagenomics allow for the study of genetic material without the need to grow cultures of a particular species in a lab, allowing researchers to study the genetic blueprints of more microbes than ever before.

Archaea are generally pretty friendly. A lot of archaea live in mutualistic relationships with other living things, meaning they provide some kind of benefit to another species and get something good in return. For example, the vast numbers of methanogens archaea that produce methane as a by-product that live in the human digestive system help to get rid of excess hydrogen by utilising it to produce energy.

This hydrogen is a waste product produced by the bacteria that help break down the food we eat, so getting rid of the excess means bacteria can do their job more effectively and efficiently. Many forms of archaea can utilise totally inorganic forms of matter—hydrogen, carbon dioxide or ammonia for example—to generate organic matter themselves. Most other living things require at least some kind of organic material to generate energy, so archaea occupy a unique place in the global food web in this regard.

Archaea may also give us a glimpse into how to look for life beyond Earth. We now know that there are so many environmental conditions—regardless of how extreme they may appear to be—that are capable of supporting life, so we can widen the boundaries of our search for life on other planets like Mars, perhaps.

Haloarchaea , for example, are known for surviving in super-salty conditions with very little water and are capable of surviving in a state of near-starvation for a very long time—as in, potentially millions of years at a time. They are generally of similar size and shape to bacteria cells. Other physical similarities they share with bacteria include a single ring of DNA , a cell wall almost always and often the presence of flagella.

Unlike bacteria, archaea are unaffected by antibiotics. Their cell walls are structurally different to those of bacteria and are not vulnerable to attack from antibiotics. Archaea cells have unique membranes. The membranes of bacteria and eukaryotic cells are made from compounds called phospholipids.

These phospholipids have non-branching tails. Archaeal membranes are made of branching lipids. The presence of branching lipids greatly alters the structure of the membranes of archaeal cells.

Archaea were originally only found in extreme environments which is where they are most commonly studied. They are now known to live in many environments that we would consider hospitable such as lakes , soil, wetlands , and oceans.

Many archaea are extremophiles i. Different groups thrive in different extreme conditions such as hot springs, salt lakes or highly acidic environments. Archaea that live in extremely salty conditions are known as extreme halophiles — lovers of salt.

Extreme halophiles are found in places such as the Dead Sea, the Great Salt Lake and Lake Assal which have salt concentrations much higher than ocean water. Other organisms die in extremely salty conditions. High concentrations of salt draw the water out of cells and cause them to die of dehydration.

Extreme halophiles have evolved adaptations to prevent their cells from losing too much water. Archaea that are found in extremely hot environments are known as extreme thermophiles. Most organisms die in extremely hot conditions because the heat damages the shape and structure of the DNA and proteins found in their cells. Acidophiles are organisms that love highly acidic conditions such as our stomachs and sulfuric pools.

Acidophiles have various methods for protecting themselves from the highly acidic conditions. Structural changes to the cellular membranes can prevent acid entering their cell. Channels in the membrane of their cell can be used to pump hydrogen ions out of the cell to maintain the pH inside the cell. Methanogens are a group of archaea that produce methane gas as a part of their metabolism. They are anaerobic microorganisms that use carbon dioxide and hydrogen to produce energy.

Methane is produced as a byproduct. Methanogens are anaerobic archaea and are poisoned by oxygen. They are commonly found in the soil of wetlands where all the oxygen has been depleted by other microorganisms. Archaea are further divided into four recognized phyla, although other phyla may exist. Of these groups the Crenarchaeota and the Euryarchaeota are most intensively studied. Classifying the archaea is somewhat challenging, since the vast majority have never been studied, and have chiefly been detected by analysis of their nucleic acids in samples from the environment.

Archaea replicate asexually in a process known as binary fission. Archaea achieve a swimming motility via one or more tail-like flagellae. Many archaeans are extremophiles, achieving wide environmental tolerance of temperature, salinity, and even radioactive environments. Archaea are thought to be significant in global geochemical cycling, since they comprise an estimated 20 percent of the world's biomass; however, very little is known about the domain, especially marine and deep-sea benthic varieties.

Very early probable prokaryotic cell fossils have been dated at approximately 3. Instead, chemical fossils of unique lipids hold greater information, since such compounds do not occur in other organisms.

Some research indicates archaean or eukaryotic lipid remains are present in shales as old as 2. Such lipids have been identified in Precambrian formations, the earliest of which are present in the Isua greenstone belt of western Greenland.

This locale boasts the Earth's oldest sediments, circa 3. Carl Woese was the first to posit that the bacteria, archaea, and eukaryotes represent separate evolutionary lines of descent that diverged at a very remote point in time on from an ancestral colony of organisms. Archaea and viruses likely had a relationship as early as 2 billion years before present day, some researchers positing that co-evolution may have been occurring between these groups at such an early time.

It has been further suggested that the last common ancestor of the bacteria and archaea was a thermophile, raising the likelihood that low temperatures are really the extreme environments viewed from an ancestral archaea point of view, and organisms that can tolerate cold conditions appeared only later in evolutionary time. It was not until that archaea were recognized as a separate domain of prokaryotes through the work of Woese and Fox. Until the chief techniques of distinguishing microorganisms were use of morphology and metabolic functions.

Woese and Fox culminated a research direction begun by a number of researchers started in the early s, in which gene coding of DNA material was viewed as a more fundamental technique for organism relatedness.

By the close of the 20th century, an enhanced understanding of the significance and ubiquity of archaea arose by using the polymerase chain reaction to detect prokaryotes in samples of water or soil based solely upon their nucleic acid. The greatest remaining puzzle is whether to acknowledge species within the domain of archaea.

While morphological and DNA findings support the recognition of species, it is not clear that significant gene transfer is prohibited, thereby annihilating the validity of species. In any case, in the present treatment we shall allow the attribution of species, if for no other reason than to follow published research designations and for simplicity of naming. Archaea and bacteria are superficially similar in size and shape, although some archaea species have remarkable geometric shapes, such as the flat and square-shaped cells of some genus Haloquadra members.

Despite this visual similarity to bacteria, archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes: notably the enzymes involved in gene transcription and translation. Other aspects of archaean biochemistry are unique, such as the occurrence on ether lipids within their cell membranes.

As with bacteria, archaea have no interior membranes or organelles. Cell membranes are typically bounded by a cell wall and motility is achieved using one or more flagellar tail structures. Archaea most resemble gram-positive bacteria. Most archaea exhibit a single plasma membrane and cell wall, lacking a periplasmic space; however, Ignicoccus manifests a notably large periplasm with membrane-bound vesicles , enclosed by an outer membrane.

Certain archaea aggregate to yield filaments of cells as long as nanometers—such forms are prominent in biofilms.

Thermococcus coalescens, on the other hand, have cells that can fuse in culturing to produce monster single cells. Genus Pyrodictium archaea form an elaborate multicell colony manifesting arrays of slender elongated hollow tubes termed cannulae that protrude from the cellular surface and connect into a dense agglomeration; this protruding form appears to encourage connection or nutrient exchange with neighboring cells of the same genus. Crenarchaeota exhibit a diverse set of geometries: irregularly shaped lobed cells, needle-like filaments that are less than nanometers in cross-section and amazing rectangular rods.

These odd morphologies are likely produced both by their cell walls as well as a prokaryotic cytoskeleton.