Editing Heterotroph (section)

== Heterotroph Impacts on Biogeochemical Cycles ==
Heterotrophs, organisms that obtain energy and carbon by consuming organic matter, are vital parts of Earth's biogeochemical cycles particularly in the carbon, nitrogen, and sulfur cycles. Their metabolic activities impact the processing and cycling of elements through ecosystems and the biosphere.

Heterotrophs are key players in the carbon cycle, acting as both consumers and decomposers. They release carbon dioxide (CO2) into the atmosphere through respiration, contributing to a large portion of carbon dioxide emissions.<ref>{{Cite journal |last=Duarte |first=Carlos M. |last2=Prairie |first2=Yves T. |date=2005-11-01 |title=Prevalence of Heterotrophy and Atmospheric CO2 Emissions from Aquatic Ecosystems |url=https://link.springer.com/article/10.1007/s10021-005-0177-4 |journal=Ecosystems |language=en |volume=8 |issue=7 |pages=862–870 |doi=10.1007/s10021-005-0177-4 |issn=1435-0629}}</ref> This process makes carbon available for autotrophs, who can fix carbon through photosynthesis or chemosynthesis. This circulation supports the continuous cycling of carbon between organic and inorganic forms.<ref>{{Cite journal |last=Falkowski |first=Paul G. |last2=Fenchel |first2=Tom |last3=Delong |first3=Edward F. |date=2008-05-23 |title=The Microbial Engines That Drive Earth's Biogeochemical Cycles |url=https://www.science.org/doi/10.1126/science.1153213 |journal=Science |volume=320 |issue=5879 |pages=1034–1039 |doi=10.1126/science.1153213}}</ref>

Heterotrophic organisms contribute to key processes in the nitrogen cycle like ammonification, the conversion of organic nitrogen to ammonia, and denitrification, the reduction of nitrate and the release of nitrogen gas to the atmosphere.<ref>{{Cite journal |last=Canfield |first=Donald E. |last2=Glazer |first2=Alexander N. |last3=Falkowski |first3=Paul G. |date=2010-10-08 |title=The Evolution and Future of Earth’s Nitrogen Cycle |url=https://www.science.org/doi/10.1126/science.1186120 |journal=Science |volume=330 |issue=6001 |pages=192–196 |doi=10.1126/science.1186120}}</ref> These processes can be known as secondary metabolism in heterotrophs.<ref>{{Cite journal |last=Martikainen |first=Pertti J. |date=2022-05-01 |title=Heterotrophic nitrification – An eternal mystery in the nitrogen cycle |url=https://linkinghub.elsevier.com/retrieve/pii/S0038071722000682 |journal=Soil Biology and Biochemistry |volume=168 |pages=108611 |doi=10.1016/j.soilbio.2022.108611 |issn=0038-0717|doi-access=free }}</ref> Heterotrophic microorganisms are essential in the mineralization of organic compounds containing nitrogen.<ref>{{Cite book |last=Werner |first=Dietrich |title=The Biology of Diatoms |publisher=University of California Press |year=1977 |pages=170-181}}</ref><ref>{{Cite book |last=Schlesinger |first=William H. |title=Biogeochemistry: an analysis of global change |last2=Bernhardt |first2=Emily S. |date=2020 |publisher=Academic Press, an imprint of Elsevier |isbn=978-0-12-814609-5 |edition=4th |location=Waltham, MA}}</ref> Through deamination, they convert organic nitrogen to ammonium (NH4+), which can be further oxidized by lithotrophs into forms available to plants. Similarly, desulfurylation by heterotrophs transforms organic sulfur into hydrogen sulfide (H2S), which is then oxidized by lithotrophs and phototrophs, contributing to the sulfur cycle.

The ability of heterotrophs to break down complex organic compounds is fundamental to nutrient cycling in ecosystems.<ref>{{Citation |last=Howarth |first=Robert W. |title=THE REGULATION OF DECOMPOSITION AND HETEROTROPHIC MICROBIAL ACTIVITY IN SALT MARSH SOILS: A REVIEW |date=1982-01-01 |work=Estuarine Comparisons |pages=183–207 |editor-last=Kennedy |editor-first=VICTOR S. |url=https://linkinghub.elsevier.com/retrieve/pii/B978012404070050017X |access-date=2025-04-22 |publisher=Academic Press |doi=10.1016/b978-0-12-404070-0.50017-x |isbn=978-0-12-404070-0 |last2=Hobbie |first2=John E.}}</ref> By decomposing dead organic matter, they release essential elements like phosphorus through dephosphorylation, making these nutrients available for other organisms.<ref>Kerr, P. C., Paris, D. F., & Brockway, D. L. (1970). ''The interrelation of carbon and phosphorus in regulating heterotrophic and autotrophic populations in aquatic ecosystems'' (Report No. FWQA-16050-FGS-07/70). U.S. Federal Water Quality Administration.</ref> This process is critical for maintaining soil fertility and supporting plant growth. Heterotrops connect the flow of energy and organic matter across ecosystems. Their biological processes link with atmospheric, chemical and geological systems.<ref>{{Cite journal |last=Jørgensen |first=Bo Barker |last2=Boetius |first2=Antje |date=October 2007 |title=Feast and famine — microbial life in the deep-sea bed |url=https://www.nature.com/articles/nrmicro1745 |journal=Nature Reviews Microbiology |language=en |volume=5 |issue=10 |pages=770–781 |doi=10.1038/nrmicro1745 |issn=1740-1534}}</ref>

Heterotrophs form intricate relationships with autotrophs in ecosystems. While they depend on autotrophs for energy-rich organic compounds, heterotrophs support autotrophic growth by releasing minerals and carbon dioxide (CO2). This interdependence is exemplified in symbiotic relationships, such as those between corals and algae, where nutrient exchange benefits both partners. Their metabolic processes depend on each other and traces of organic compounds.<ref>{{Cite journal |last=Tran |first=Ngoc Han |last2=Urase |first2=Taro |last3=Ngo |first3=Huu Hao |last4=Hu |first4=Jiangyong |last5=Ong |first5=Say Leong |date=2013-10-01 |title=Insight into metabolic and cometabolic activities of autotrophic and heterotrophic microorganisms in the biodegradation of emerging trace organic contaminants |url=https://linkinghub.elsevier.com/retrieve/pii/S0960852413011516 |journal=Bioresource Technology |volume=146 |pages=721–731 |doi=10.1016/j.biortech.2013.07.083 |issn=0960-8524}}</ref>

The biogeochemical activities of heterotrophs are thus integral to ecosystem functioning, influencing the availability of nutrients, the composition of the atmosphere, and the productivity of both terrestrial and aquatic environments.