Editing Primary nutritional groups (section)

==Examples==
All sorts of combinations may exist in nature, but some are more common than others. For example, most plants are ''photolithoautotrophic'', since they use light as an energy source, water as electron donor, and {{CO2}} as a carbon source. All animals and fungi are [[chemo-organo-heterotrophic|''chemoorganoheterotrophic'']], since they use organic substances both as chemical energy sources and as electron/hydrogen donors and carbon sources. Some [[Eukaryote|eukaryotic]] microorganisms, however, are not limited to just one nutritional mode. For example, some algae live photoautotrophically in the light, but shift to chemoorganoheterotrophy in the dark. Even higher plants retained their ability to respire heterotrophically on starch at night which had been synthesised phototrophically during the day.

[[Prokaryote]]s show a great diversity of [[microbial metabolism|nutritional categories]].<ref name="TangTangBlankenship 2011">{{cite journal |vauthors=Tang KH, Tang YJ, Blankenship RE |title=Carbon metabolic pathways in phototrophic bacteria and their broader evolutionary implications |journal=Front Microbiol |volume=2 |issue= |pages=165 |date=2011 |pmid=21866228 |pmc=3149686 |doi=10.3389/fmicb.2011.00165 |doi-access=free }}</ref> For example, [[cyanobacteria]] and many [[purple sulfur bacteria]] can be ''photolithoautotrophic'', using light for energy, {{H2O}} or sulfide as electron/hydrogen donors, and {{CO2}} as carbon source, whereas [[green non-sulfur bacteria]] can be ''photoorganoheterotrophic'', using organic molecules as both electron/hydrogen donors and carbon sources.<ref name="Morris 2019" /><ref name="TangTangBlankenship 2011" /> Many bacteria are ''chemoorganoheterotrophic'', using organic molecules as energy, electron/hydrogen and carbon sources.<ref name="Morris 2019" /> Some bacteria are limited to only one nutritional group, whereas others are facultative and switch from one mode to the other, depending on the nutrient sources available.<ref name="TangTangBlankenship 2011" /> [[Lithotroph|Sulfur-oxidizing]], [[Iron-oxidizing bacteria|iron]], and [[anammox]] bacteria as well as [[methanogen]]s are [[Lithoautotroph|''chemolithoautotrophs'']], using inorganic energy, electron, and carbon sources. ''[[Lithotroph#Lithoheterotrophs versus lithoautotrophs|Chemolithoheterotrophs]]'' are rare because heterotrophy implies the availability of organic substrates, which can also serve as easy electron sources, making lithotrophy unnecessary. ''Photoorganoautotrophs'' are uncommon since their organic source of electrons/hydrogens would provide an easy carbon source, resulting in heterotrophy.

[[Synthetic biology]] efforts enabled the transformation of the trophic mode of two [[Model organism|model microorganisms]] from heterotrophy to chemoorganoautotrophy:

* ''[[Escherichia coli]]'' was [[Genetic engineering|genetically engineered]] and then [[Adaptive laboratory evolution|evolved in the laboratory]] to use {{CO2}} as the sole carbon source while using the one-carbon molecule [[formate]] as the source of electrons.<ref name=Gleizer19/>
* The [[methylotroph]]ic ''[[Pichia pastoris]]'' yeast was genetically engineered to use {{CO2}} as the carbon source instead of [[methanol]], while the latter remained the source of electrons for the cells.<ref name=Gassler19/>