Autotroph

Source: Wikipedia, the free encyclopedia.
"Producer (biology)" redirects here. For other uses, see Producer (disambiguation).
See also: Primary production
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 is an organism that produces complex

heterotrophs as consumers of autotrophs or other heterotrophs). Autotrophs can reduce carbon dioxide to make organic compounds for biosynthesis and as stored chemical fuel. Most autotrophs use water as the reducing agent, but some can use other hydrogen compounds such as hydrogen sulfide
.

The

chemoautotrophs, and are frequently found in hydrothermal vents in the deep ocean. Primary producers are at the lowest trophic level, and are the reasons why Earth sustains life to this day.[4]

Most chemoautotrophs are lithotrophs, using inorganic electron donors such as hydrogen sulfide, hydrogen gas, elemental sulfur, ammonium and ferrous oxide as reducing agents and hydrogen sources for biosynthesis and chemical energy release. Autotrophs use a portion of the ATP produced during photosynthesis or the oxidation of chemical compounds to reduce NADP+ to NADPH to form organic compounds.[5]

History

The term autotroph was coined by the German botanist

hydrogen sulphide. Due to the scarcity of hydrogen sulphide, some photosynthetic bacteria evolved to use water in photosynthesis, leading to cyanobacteria.[8]

Variants

Some organisms rely on

inorganic compounds as a source of energy. Such organisms are mixotrophs. 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 and energy from the oxidation of inorganic compounds is termed a chemolithoheterotroph
.

Evidence suggests that some fungi may also

Chernobyl nuclear power plant.[9]

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

Examples

There are many different types of primary producers out in the Earth's ecosystem at different states. Fungi and other organisms that gain their biomass from oxidizing organic materials are called decomposers and are not primary producers. However, lichens located in tundra climates are an exceptional example of a primary producer that, by mutualistic symbiosis, combines photosynthesis by algae (or additionally nitrogen fixation by cyanobacteria) with the protection of a decomposer fungus. Also, plant-like primary producers (trees, algae) use the sun as a form of energy and put it into the air for other organisms.[3] There are of course H2O primary producers, including a form of bacteria, and phytoplankton. As there are many examples of primary producers, two dominant types are coral and one of the many types of brown algae, kelp.[3]

Photosynthesis

Gross primary production occurs by photosynthesis. This is also the main way that primary producers take energy and produce/release it somewhere else. Plants, coral, bacteria, and algae do this. During photosynthesis, primary producers take energy from the sun and convert it into energy, sugar, and oxygen. Primary producers also need the energy to convert this same energy elsewhere, so they get it from nutrients. One type of nutrient is nitrogen.[4][3]

Ecology

maidenhair fern
, a photoautotroph
See also: Primary production

Without primary producers, organisms that are capable of producing energy on their own, the biological systems of Earth would be unable to sustain themselves.[3] Plants, along with other primary producers, produce the energy that other living beings consume, and the oxygen that they breathe.[3] It is thought that the first organisms on Earth were primary producers located on the ocean floor.[3]

Autotrophs are fundamental to the food chains of all

Carnivorous organisms rely on autotrophs indirectly, as the nutrients
obtained from their heterotrophic prey come from autotrophs they have consumed.

Most ecosystems are supported by the autotrophic

heterotrophs.[11] Proteins can be made using nitrates, sulfates, and phosphates in the soil.[12][13]

Primary production in tropical streams and rivers

Aquatic algae are a significant contributor to food webs in tropical rivers and streams. This is displayed by net primary production, a fundamental ecological process that reflects the amount of carbon that is synthesized within an ecosystem. This carbon ultimately becomes available to consumers. Net primary production displays that the rates of in-stream primary production in tropical regions are at least an order of magnitude greater than in similar temperate systems.[14]

Origin of autotrophs

Main article: Abiogenesis § Deep sea hydrothermal vents

Researchers believe that the first cellular lifeforms were not heterotrophs as they would rely upon autotrophs since organic substrates that were delivered from space was either too heterogeneous to support microbial growth or too reduced to be fermented. Instead, they consider that the first cells were autotrophs.[15] These autotrophs might have been thermophilic and anaerobic chemolithoautotrophs that lived at deep sea alkaline hydrothermal vents. Catalytic Fe(Ni)S minerals at these environments are shown to catalyze biomolecules like RNA.[16] This view is supported by phylogenetic evidence as the physiology and habitat of the last universal common ancestor (LUCA) was inferred to have also been a thermophilic anaerobe with a Wood-Ljungdahl pathway, its biochemistry was replete with FeS clusters and radical reaction mechanisms, and was dependent upon Fe, H2, and CO2.[15][17] The high concentration of K+ present within the cytosol of most life forms suggest that early cellular life had Na+/H+ antiporters or possibly symporters.[18] Autotrophs possibly evolved into heterotrophs when they were at low H2 partial pressures where the first form of heterotrophy were likely amino acid and clostridial type purine fermentations[19] and photosynthesis emerged in the presence of long-wavelength geothermal light emitted by hydrothermal vents. The first photochemically active pigments are inferred to be Zn-tetrapyrroles.[20]

See also

References

  1. ISBN 978-1319017637
  2. ^ Chang, Kenneth (12 September 2016). "Visions of Life on Mars in Earth's Depths". The New York Times. Archived from the original on 12 September 2016. Retrieved 12 September 2016.
  3. ^ a b c d e f g "What Are Primary Producers?". Sciencing. Archived from the original on 14 October 2019. Retrieved 8 February 2018.
  4. ^
    doi:10.1890/0012-9658(2002)083[0703:USITET]2.0.CO;2
    .
  5. ^ Mauseth, James D. (2008). Botany: An Introduction to Plant Biology (4 ed.). Jones & Bartlett Publishers. p. 252.
    ISBN 978-0-7637-5345-0
    .
  6. ^ Frank, Albert Bernard (1892–93). Lehrbuch der Botanik (in German). Leipzig: W. Engelmann. Archived from the original on 7 March 2023. Retrieved 14 January 2018.
  7. S2CID 263839383. Archived
    from the original on 15 March 2024. Retrieved 5 December 2023.
  8. ^ Townsend, Rich (13 October 2019). "The Evolution of Autotrophs". University of Wisconsin-Madison Department of Astronomy. Archived from the original on 8 July 2022. Retrieved 3 May 2019.
  9. ^ Melville, Kate (23 May 2007). "Chernobyl fungus feeds on radiation". Archived from the original on 4 February 2009. Retrieved 18 February 2009.
  10. OCLC 868970980.{{cite book}}: CS1 maint: location missing publisher (link
    )
  11. ISBN 978-0-19-914065-7. Archived
    from the original on 15 March 2024. Retrieved 16 August 2020.
  12. OCLC 56476957.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link
    )
  13. ISBN 978-1-4067-7315-6. Archived
    from the original on 15 March 2024. Retrieved 16 August 2020.
  14. ISBN 9780120884490
    .
  15. ^
    PMID 30114187
    .
  16. PMID 17255002
    .
  17. PMID 17008222
    .
  18. PMID 23754820
    .
  19. PMID 26578093. Archived
    from the original on 15 March 2024. Retrieved 4 December 2022.
  20. PMID 29177446
    .

External links


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