In biochemistry, chemosynthesis is the biological conversion of one or more carbon-containing molecules (usually
carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
or
methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...
) and nutrients into organic matter using the
oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
of inorganic compounds (e.g.,
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
gas,
hydrogen sulfide) or
ferrous
In chemistry, the adjective Ferrous indicates a compound that contains iron(II), meaning iron in its +2 oxidation state, possibly as the divalent cation Fe2+. It is opposed to " ferric" or iron(III), meaning iron in its +3 oxidation state, suc ...
ions as a source of energy, rather than sunlight, as in
photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
.
Chemoautotrophs,
organism
In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...
s that obtain carbon from
carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
through chemosynthesis, are phylogenetically diverse. Groups that include conspicuous or biogeochemically-important taxa include the sulfur-oxidizing
Gammaproteobacteria, the
Campylobacterota
Campylobacterota are a phylum of bacteria. All species of this phylum are Gram-negative.
The Campylobacterota consist of few known genera, mainly the curved to spirilloid ''Wolinella'' spp., ''Helicobacter'' spp., and ''Campylobacter'' spp. Most ...
, the
Aquificota
The ''Aquificota'' phylum is a diverse collection of bacteria that live in harsh environmental settings. The name ''Aquificota'' was given to this phylum based on an early genus identified within this group, '' Aquifex'' (“water maker”), whic ...
, the
methanogenic archaea, and the neutrophilic
iron-oxidizing bacteria
Iron-oxidizing bacteria are chemotrophic bacteria that derive energy by oxidizing dissolved ferrous iron. They are known to grow and proliferate in waters containing iron concentrations as low as 0.1 mg/L. However, at least 0.3 ppm of dissolved ox ...
.
Many microorganisms in dark regions of the oceans use chemosynthesis to produce biomass from single-carbon molecules. Two categories can be distinguished. In the rare sites where hydrogen molecules (H
2) are available, the energy available from the reaction between CO
2 and H
2 (leading to production of methane, CH
4) can be large enough to drive the production of biomass. Alternatively, in most oceanic environments, energy for chemosynthesis derives from reactions in which substances such as
hydrogen sulfide or
ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
are oxidized. This may occur with or without the presence of oxygen.
Many chemosynthetic microorganisms are consumed by other organisms in the ocean, and
symbiotic associations between chemosynthesizers and respiring heterotrophs are quite common. Large populations of animals can be supported by chemosynthetic
secondary production at
hydrothermal vents,
methane clathrate
Methane clathrate (CH4·5.75H2O) or (8CH4·46H2O), also called methane hydrate, hydromethane, methane ice, fire ice, natural gas hydrate, or gas hydrate, is a solid clathrate compound (more specifically, a clathrate hydrate) in which a large amo ...
s,
cold seep
A cold seep (sometimes called a cold vent) is an area of the ocean floor where hydrogen sulfide, methane and other hydrocarbon-rich fluid seepage occurs, often in the form of a brine pool. ''Cold'' does not mean that the temperature of the see ...
s,
whale fall
A whale fall occurs when the carcass of a whale has fallen onto the ocean floor at a depth greater than , in the bathyal or abyssal zones. On the sea floor, these carcasses can create complex localized ecosystems that supply sustenance to deep- ...
s, and
isolated cave water.
It has been hypothesized that anaerobic chemosynthesis may support life below the surface of
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
,
Jupiter's moon
Europa, and other planets. Chemosynthesis may have also been the first type of metabolism that evolved on Earth, leading the way for cellular respiration and photosynthesis to develop later.
Hydrogen sulfide chemosynthesis process
Giant tube worm
''Riftia pachyptila'', commonly known as the giant tube worm and less commonly known as the Giant beardworm, is a marine invertebrate in the phylum Annelida (formerly grouped in phylum Pogonophora and Vestimentifera) related to tube worm ...
s use bacteria in their
trophosome A trophosome is a highly vascularised organ found in some animals that houses symbiotic bacteria that provide food for their host. Trophosomes are located in the coelomic cavity in the vestimentiferan tube worms (Siboglinidae, e.g. the giant tube wo ...
to
fix carbon dioxide (using
hydrogen sulfide as their energy source) and produce sugars and
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...
s.
Some reactions produce sulfur:
:hydrogen sulfide chemosynthesis:
[
]
::18H
2S + 6CO
2 + 3
O2 → C
6H
12O
6 (
carbohydrate
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or m ...
) + 12H
2O + 18
S
Instead of releasing
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
gas while fixing carbon dioxide as in
photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
, hydrogen sulfide chemosynthesis produces solid globules of
sulfur in the process. In bacteria capable of chemoautotrophy (a form a chemosynthesis), such as
purple sulfur bacteria
The purple sulfur bacteria (PSB) are part of a group of Pseudomonadota capable of photosynthesis, collectively referred to as purple bacteria. They are anaerobic or microaerophilic, and are often found in stratified water environments including ...
, yellow globules of sulfur are present and visible in the cytoplasm.
Discovery
In 1890,
Sergei Winogradsky proposed a novel type of life process called "anorgoxydant". His discovery suggested that some microbes could live solely on inorganic matter and emerged during his physiological research in the 1880s in
Strasbourg and
Zürich
, neighboring_municipalities = Adliswil, Dübendorf, Fällanden, Kilchberg, Maur, Oberengstringen, Opfikon, Regensdorf, Rümlang, Schlieren, Stallikon, Uitikon, Urdorf, Wallisellen, Zollikon
, twintowns = Kunming, San Francisco
Zürich ...
on sulfur, iron, and nitrogen bacteria.
In 1897,
Wilhelm Pfeffer
Wilhelm Friedrich Philipp Pfeffer (9 March 1845 – 31 January 1920) was a German botanist and plant physiologist born in Grebenstein.
Academic career
He studied chemistry and pharmacy at the University of Göttingen, where his instructors incl ...
coined the term "chemosynthesis" for the energy production by oxidation of inorganic substances, in association with
autotrophic
An autotroph or primary producer is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) using carbon from simple substances such as carbon dioxide,Morris, J. et al. (2019). "Biology: How Life Works", ...
carbon dioxide assimilation—what would be named today as chemolithoautotrophy. Later, the term would be expanded to include also chemoorganoautotrophs, which are organisms that use organic energy substrates in order to assimilate carbon dioxide. Thus, chemosynthesis can be seen as a synonym of
chemoautotrophy
A Chemotroph is an organism that obtains energy by the oxidation of electron donors in their environments. These molecules can be organic (chemoorganotrophs) or inorganic (chemolithotrophs). The chemotroph designation is in contrast to phototrop ...
.
The term "
chemotroph
A Chemotroph is an organism that obtains energy by the oxidation of electron donors in their environments. These molecules can be organic (chemoorganotrophs) or inorganic ( chemolithotrophs). The chemotroph designation is in contrast to phototr ...
y", less restrictive, would be introduced in the 1940s by
André Lwoff
André — sometimes transliterated as Andre — is the French and Portuguese form of the name Andrew, and is now also used in the English-speaking world. It used in France, Quebec, Canada and other French-speaking countries. It is a variation ...
for the production of energy by the oxidation of electron donors, organic or not, associated with auto- or heterotrophy.
Hydrothermal vents
The suggestion of Winogradsky was confirmed nearly 90 years later, when hydrothermal
ocean
The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...
vents were predicted to exist in the 1970s. The hot springs and strange creatures were discovered by ''
Alvin
Alvin may refer to:
Places Canada
*Alvin, British Columbia United States
*Alvin, Colorado
*Alvin, Georgia
*Alvin, Illinois
* Alvin, Michigan
*Alvin, Texas
* Alvin, Wisconsin, a town
*Alvin (community), Wisconsin, an unincorporated community
Other ...
'', the world's first deep-sea submersible, in 1977 at the
Galapagos Rift. At about the same time, then-graduate student
Colleen Cavanaugh proposed chemosynthetic bacteria that oxidize sulfides or elemental sulfur as a mechanism by which
tube worms could survive near hydrothermal vents. Cavanaugh later managed to confirm that this was indeed the method by which the worms could thrive, and is generally credited with the discovery of chemosynthesis.
A 2004
television
Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...
series hosted by
Bill Nye named chemosynthesis as one of the 100 greatest scientific discoveries of all time.
Oceanic crust
In 2013, researchers reported their discovery of bacteria living in the rock of the
oceanic crust
Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic ...
below the thick layers of sediment, and apart from the hydrothermal vents that form along the edges of the
tectonic plate
Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...
s. Preliminary findings are that these bacteria subsist on the hydrogen produced by chemical reduction of
olivine
The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickl ...
by seawater circulating in the small veins that permeate the
basalt
Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...
that comprises oceanic crust. The bacteria synthesize methane by combining hydrogen and carbon dioxide.
Chemosynthesis as an innovation for researches
Despite the fact that the process of chemosynthesis has been known for more than a hundred years, its significance and importance are still relevant today in the transformation of chemical elements in biogeochemical cycles. Today, the vital processes of nitrifying bacteria, which lead to the oxidation of ammonia to nitric acid, require scientific substantiation and additional research. The ability of bacteria to convert inorganic substances into organic ones suggests that chemosynthetics can accumulate valuable resources for human needs.
Chemosynthetic communities in different environments are important biological systems in terms of their ecology, evolution and biogeography, as well as their potential as indicators of the availability of permanent hydrocarbon- based energy sources. In the process of chemosynthesis, bacteria produce organic matter where photosynthesis is impossible. Isolation of thermophilic sulfate-reducing bacteria ''Thermodesulfovibrio yellowstonii'' and other types of chemosynthetics provides prospects for further research. Thus, the importance of chemosynthesis remains relevant for use in innovative technologies, conservation of ecosystems, human life in general. The role of
Sergey Winogradsky in discovering the phenomenon of chemosynthesis is underestimated and needs further research and popularization.
See also
*
Primary nutritional groups
Primary nutritional groups are groups of organisms, divided in relation to the nutrition mode according to the sources of energy and carbon, needed for living, growth and reproduction. The sources of energy can be light or chemical compounds; the ...
*
Autotroph
An autotroph or primary producer is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) using carbon from simple substances such as carbon dioxide,Morris, J. et al. (2019). "Biology: How Life Wo ...
*
Heterotroph
A heterotroph (; ) is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but ...
*
Photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
*
Movile Cave
Movile Cave () is a cave near Mangalia, Constanța County, Romania discovered in 1986 by Cristian Lascu a few kilometers from the Black Sea coast. It is notable for its unique groundwater ecosystem abundant in hydrogen sulfide and carbon dioxi ...
References
External links
Chemosynthetic Communities in the Gulf of Mexico
{{modelling ecosystems
Biological processes
Metabolism
Environmental microbiology
Ecosystems