Editing Heterotroph (section)

==Types==
Heterotrophs can be [[organotroph]]s or [[lithotroph]]s. Organotrophs exploit reduced carbon compounds as electron sources, like [[carbohydrates]], [[fat]]s, and [[proteins]] from plants and animals. On the other hand, lithoheterotrophs use inorganic compounds, such as [[ammonium]], [[nitrite]], or [[sulfur]], to obtain electrons. Another way of classifying different heterotrophs is by assigning them as [[chemotroph]]s or [[phototroph]]s. Phototrophs utilize light to obtain energy and carry out metabolic processes, whereas chemotrophs use the energy obtained by the oxidation of chemicals from their environment.<ref>{{cite book |last1=Mills |first1=A.L. |title=The Environmental Geochemistry of Mineral Deposits: Part A: Processes, Techniques, and Health Issues Part B: Case Studies and Research Topics |year=1997 |publisher=Society of Economic Geologists |isbn=978-1-62949-013-7 |pages=125–132 |url=http://lmecol.evsc.virginia.edu/pubs/C13-Mills_Bull%20Econ%20Geol%20.PDF |access-date=9 October 2017 |archive-date=6 April 2019 |archive-url=https://web.archive.org/web/20190406194730/https://lmecol.evsc.virginia.edu/pubs/C13-Mills_Bull%20Econ%20Geol%20.PDF |url-status=dead }}</ref>

Photoorganoheterotrophs, such as [[Rhodospirillaceae]] and purple non-sulfur bacteria synthesize organic compounds using sunlight coupled with oxidation of organic substances.
They use organic compounds to build structures. They do not fix carbon dioxide and apparently do not have the [[Light-independent reactions#Calvin Cycle|Calvin cycle]].<ref name="botany">{{cite book |last=Mauseth |first=James D. |title=Botany: An introduction to plant biology |year=2008 |edition=4th |publisher=Jones & Bartlett Publishers |page=[https://archive.org/details/botanyintroducti0000maus_k4i0/page/252 252] |url=https://archive.org/details/botanyintroducti0000maus_k4i0 |url-access=registration |quote=heterotroph fix carbon. |isbn=978-0-7637-5345-0}}</ref> Chemolithoheterotrophs like ''Oceanithermus profundus''<ref>{{cite journal |author1=Miroshnichenko, M.L. |author2=L'Haridon, S. |author3=Jeanthon, C. |author4=Antipov, A.N. |author5=Kostrikina, N.A. |author6=Tindall, B.J. |author7=Schumann, P. |author8=Spring, S. |author9=Stackebrandt, E. |author10=Bonch-Osmolovskaya, E.A. |display-authors=6 |date=1 May 2003 |journal=International Journal of Systematic and Evolutionary Microbiology |volume=53 |issue=3 |pages=747–752 |doi=10.1099/ijs.0.02367-0 |pmid=12807196 |title=Oceanithermus profundus gen. nov., sp. nov., a thermophilic, microaerophilic, facultatively chemolithoheterotrophic bacterium from a deep-sea hydrothermal vent|doi-access=free }}</ref> obtain energy from the oxidation of inorganic compounds, including [[hydrogen sulfide]], elemental [[sulfur]], [[thiosulfate]], and molecular [[hydrogen]]. [[Mixotroph]]s (or facultative chemolithotroph) can use either carbon dioxide or organic carbon as the carbon source, meaning that mixotrophs have the ability to use both heterotrophic and autotrophic methods.<ref name="biogeochemistry">{{cite book |last=Libes |first=Susan M. |title=Introduction to Marine Biogeochemistry |year=2009 |edition=2nd |publisher=Academic Press |page=192 |url=https://books.google.com/books?id=KVZJUw4nORgC&q=chemolithoheterotrophs+inorganic&pg=PA192 |isbn=978-0-12-088530-5}}</ref><ref name="prokaryotes">{{cite book |last=Dworkin |first=Martin |title=The prokaryotes: ecophysiology and biochemistry |year=2006 |edition=3rd |publisher=Springer |page=988 |url=https://books.google.com/books?id=uleTr2jKzJMC&q=chemolithoheterotroph+chemoorganoheterotroph&pg=PA988 |isbn=978-0-387-25492-0}}</ref>
Although mixotrophs have the ability to grow under both heterotrophic and autotrophic conditions, ''C. vulgaris'' have higher biomass and lipid productivity when growing under heterotrophic compared to autotrophic conditions.<ref>{{cite journal |last1=Liang |first1=Yanna |title=Biomass and lipid productivities of Chlorella vulgaris under autotrophic, heterotrophic and mixotrophic growth conditions |journal=Biotechnology Letters |date=July 2009 |volume=31 |issue=7 |pages=1043–1049 |doi=10.1007/s10529-009-9975-7 |pmid=19322523|s2cid=1989922 }}</ref>

Heterotrophs, by consuming reduced carbon compounds, are able to use all the energy that they obtain from food for growth and reproduction, unlike autotrophs, which must use some of their energy for carbon fixation.<ref name="botany" /> Both heterotrophs and autotrophs alike are usually dependent on the metabolic activities of other organisms for nutrients other than carbon, including nitrogen, phosphorus, and sulfur, and can die from lack of food that supplies these nutrients.<ref>{{cite book |last1=Campbell and Reece |title=Biology |url=https://archive.org/details/biologyc00camp |url-access=registration |year=2002 |publisher=Benjamin-Cummings Publishing Co. |isbn=978-0805371710 |edition=7th}}</ref> This applies not only to animals and fungi but also to bacteria.<ref name="botany" />