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of or relating to organisms (as green plants) that can make complex organic nutritive compounds from simple inorganic sources by photosynthesis (同)autophytic

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/01/24 21:11:31」(JST)

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Overview of cycle between autotrophs and heterotrophs. Photosynthesis is the main means by which plants, algae and many bacteria produce organic compounds and oxygen from carbon dioxide and water (green arrow).

An autotroph^[α] ("self-feeding", from the Greek autos "self" and trophe "nourishing") or "producer", is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) from simple substances present in its surroundings, generally using energy from light (photosynthesis) or inorganic chemical reactions (chemosynthesis). They are the producers in a food chain, such as plants on land or algae in water, in contrast to heterotrophs as consumers of autotrophs. They are able to make their own food, and do not need a living energy or organic carbon source. Autotrophs can reduce carbon dioxide to make organic compounds, creating a store of chemical energy. Most autotrophs use water as the reducing agent, but some can use other hydrogen compounds such as hydrogen sulfide. Phototrophs(ie. green plants & algae), a type of autotroph, convert physical energy from sunlight into chemical energy in the form of reduced carbon.

Autotrophs can be phototrophs or chemotrophs. Phototrophs use light as an energy source, while chemotrophs utilize electron donors as a source of energy, whether from organic or inorganic sources; however in the case of autotrophs, these electron donors come from inorganic chemical sources. Such chemotrophs are lithotrophs. Lithotrophs use inorganic compounds, such as hydrogen sulfide, elemental sulfur, ammonium and ferrous iron, as reducing agents for biosynthesis and chemical energy storage. Photoautotrophs and lithoautotrophs use a portion of the ATP produced during photosynthesis or the oxidation of inorganic compounds to reduce NADP⁺ to NADPH in order to form organic compounds.^[1]

Ecology[edit]

Green fronds of a maidenhair fern, a photoautotroph

Autotrophs are fundamental to the food chains of all ecosystems in the world. They take energy from the environment in the form of sunlight or inorganic chemicals and use it to create energy-rich molecules such as carbohydrates. This mechanism is called primary production. Other organisms, called heterotrophs, take in autotrophs as food to carry out functions necessary for their life. Thus, heterotrophs — all animals, almost all fungi, as well as most bacteria and protozoa — depend on autotrophs for the energy and raw materials they need. Heterotrophs obtain energy by breaking down organic molecules (carbohydrates, fats, and proteins) obtained in food. Carnivorous organisms ultimately rely on autotrophs because the nutrients obtained from their heterotroph prey come from autotrophs they consumed.They are in animal cells

Most ecosystems are supported by the autotrophic primary production of plants that capture photons initially released by nuclear fusion reactions in the sun. The process of photosynthesis splits a water molecule (H₂O), releasing oxygen (O₂) into the atmosphere, and reducing carbon dioxide (CO₂) to release the hydrogen atoms that fuel the metabolic process of primary production. Plants convert and store the energy of the photon into the chemical bonds of simple sugars during photosynthesis. These plant sugars are polymerized for storage as long-chain carbohydrates, including other sugars, starch, and cellulose; glucose is also used to make fats and proteins. When autotrophs are eaten by heterotrophs, i.e., consumers such as animals, the carbohydrates, fats, and proteins contained in them become energy sources for the heterotrophs.^[2] Proteins can be made using nitrates, sulfates, and phosphates in the soil.^[3]^[4]

Variants[edit]

Some organisms rely on organic compounds as a source of carbon, but are able to use light or inorganic compounds as a source of energy. Such organisms are not defined as autotrophic, but rather as heterotrophic. An organism that obtains carbon from organic compounds but obtains energy from light is called a photoheterotroph, while an organism that obtains carbon from organic compounds but obtains energy from the oxidation of inorganic compounds is termed a chemoheterotroph, chemolithoheterotroph, or lithoheterotroph.

Evidence suggests that some fungi may also obtain energy from radiation. Such radiotrophic fungi were found growing inside a reactor of the Chernobyl nuclear power plant.^[5]

Flowchart[edit]

Flowchart to determine if a species is autotroph, heterotroph, or a subtype

Autotroph
- Chemoautotroph
- Photoautotroph
Heterotroph
- Chemoheterotroph
- Photoheterotroph

References[edit]

^ Mauseth, James D. (2008). Botany: An Introduction to Plant Biology (4 ed.). Jones & Bartlett Publishers. p. 252. ISBN 978-0-7637-5345-0.
^ Beckett, Brian S. (1981). Illustrated Human and Social Biology. Oxford University Press. p. 38. ISBN 978-0-19-914065-7.
^ Odum, E. P.; Barrett, G. W. (2005). Fundamentals of ecology. Brooks Cole. p. 598. ISBN 978-0-534-42066-6.
^ Smith, Gilbert M. (2007). A Textbook of General Botany. READ BOOKS. p. 148. ISBN 978-1-4067-7315-6.
^ Melville, Kate (23 May 2007). "Chernobyl Fungus Feeds On Radiation". Archived from the original on 4 February 2009. Retrieved 18 February 2009.

Footnotes[edit]

α. ^{^} The word autotroph comes from the Greek autos "self" and trophe "nutrition," related to trephein "to make solid, congeal, thicken".

English Journal

Expression and activity of the Calvin-Benson-Bassham cycle transcriptional regulator CbbR from Acidithiobacillus ferrooxidans in Ralstonia eutropha.

Esparza M1, Jedlicki E2, Dopson M3, Holmes DS4.
FEMS microbiology letters.FEMS Microbiol Lett.2015 Aug;362(15):fnv108. doi: 10.1093/femsle/fnv108. Epub 2015 Jul 6.
Autotrophic fixation of carbon dioxide into cellular carbon occurs via several pathways but quantitatively, the Calvin-Benson-Bassham cycle is the most important. CbbR regulates the expression of the cbb genes involved in CO2 fixation via the Calvin-Benson-Bassham cycle in a number of autotrophic ba
PMID 26152700

Does the stoichiometric carbon:phosphorus knife edge apply for predaceous copepods?

Laspoumaderes C1, Modenutti B, Elser JJ, Balseiro E.
Oecologia.Oecologia.2015 Jun;178(2):557-69. doi: 10.1007/s00442-014-3155-8. Epub 2015 Feb 7.
Recent work has indicated that stoichiometric food quality in terms of the carbon:phosphorus (C:P) ratio affects consumers whether the imbalance involves a deficit or an excess of nutrients; hence, organisms exist on a "stoichiometric knife edge". While previous studies have focused primarily on aut
PMID 25663329

Draft Genome Sequence of a Sulfur-Oxidizing Autotroph, Sulfuricella sp. Strain T08, Isolated from a Freshwater Lake.

Watanabe T1, Kojima H2, Fukui M2.
Genome announcements.Genome Announc.2015 May 21;3(3). pii: e00498-15. doi: 10.1128/genomeA.00498-15.
Sulfuricella sp. strain T08 is a sulfur-oxidizing autotroph newly isolated from a freshwater lake in Japan. Strain T08 is the second isolate of the genus Sulfuricella. Here, we report the annotated draft genome sequence of the isolate. Copyright © 2015 Watanabe et al.
PMID 25999549

Japanese Journal

Global meta-analysis for controlling factors on carbon stable isotope ratios of lotic periphyton.

Ishikawa Naoto F,Doi Hideyuki,Finlay Jacques C
Oecologia 170(2), 541-549, 2012-10
… Longitudinal increases in δ(13)C indicate the importance of in-stream processes on lotic carbon cycles and autotroph δ(13)C variation. … Autotroph δ(13)C varied among taxonomic groups. …
NAID 120004920409

The ontogenetic stoichiometric bottleneck stabilizes herbivore-autotroph dynamics

Nakazawa Takefumi
Ecological research 26(1), 209-216, 2011-01-01
NAID 10027881361

3-ヒドロキシプロピオン酸サイクルで機能する炭酸固定反応

石井正浩
日本農芸化学会誌 77(4), 413-416, 2003-04-01
NAID 80015878812

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