A mixotroph is a microorganism that can use a mix of different sources of energy and carbon

Primary nutritional groups

Primary nutritional groups are groups of organisms, divided according to the sources of energy and carbon, needed for living, growth and reproduction...

. Possible are alternations between photo-

Phototroph

Phototrophs are the organisms that carry out photosynthesis to acquire energy. They use the energy from sunlight to convert carbon dioxide and water into organic material to be utilized in cellular functions such as biosynthesis and respiration.Most phototrophs are autotrophs, also known as...

 and chemotroph

Chemotroph

Chemotrophs are organisms that obtain energy by the oxidation of electron donors in their environments. These molecules can be organic or inorganic . The chemotroph designation is in contrast to phototrophs, which utilize solar energy...

y, between litho-

Lithotroph

A lithotroph is an organism that uses an inorganic substrate to obtain reducing equivalents for use in biosynthesis or energy conservation via aerobic or anaerobic respiration. Known chemolithotrophs are exclusively microbes; No known macrofauna possesses the ability to utilize inorganic...

 and organotroph

Organotroph

An organotroph is an organism that obtains hydrogen or electrons from organic substrates . Antonym: Lithotroph- See also :* Lithotroph* Heterotroph* Primary nutritional groups...

y, between auto-

Autotroph

An autotroph, or producer, is an organism that produces complex organic compounds from simple inorganic molecules using energy from light or inorganic chemical reactions . They are the producers in a food chain, such as plants on land or algae in water...

 and heterotroph

Heterotroph

A heterotroph is an organism that cannot fix carbon and uses organic carbon for growth. This contrasts with autotrophs, such as plants and algae, which can use energy from sunlight or inorganic compounds to produce organic compounds such as carbohydrates, fats, and proteins from inorganic carbon...

y or a combination of it. Mixotrophs can be either eukaryotic

Eukaryote

A eukaryote is an organism whose cells contain complex structures enclosed within membranes. Eukaryotes may more formally be referred to as the taxon Eukarya or Eukaryota. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear...

 or prokaryotic

Prokaryote

The prokaryotes are a group of organisms that lack a cell nucleus , or any other membrane-bound organelles. The organisms that have a cell nucleus are called eukaryotes. Most prokaryotes are unicellular, but a few such as myxobacteria have multicellular stages in their life cycles...

.

They can take advantage of different environmental conditions.

If a trophic mode is obligate, then it is always necessary for sustaining growth and maintenance; if facultative, it can be used as a supplemental source. Some organisms have incomplete Calvin cycle

Calvin cycle

The Calvin cycle or Calvin–Benson-Bassham cycle or reductive pentose phosphate cycle or C3 cycle or CBB cycle is a series of biochemical redox reactions that take place in the stroma of chloroplasts in photosynthetic organisms...

s, so they are incapable of fixing carbon dioxide and must use organic carbon sources.

Examples

• Paracoccus pantotrophus
  Paracoccus
  In taxonomy, Paracoccus is a genus of the Rhodobacteraceae.-External links:...
  
  is a bacterium that can live as chemoorganoheterotroph, whereby a large variety of organic compounds can be metabolized. Also a facultative chemolithoautotrophic
  Lithotroph
  A lithotroph is an organism that uses an inorganic substrate to obtain reducing equivalents for use in biosynthesis or energy conservation via aerobic or anaerobic respiration. Known chemolithotrophs are exclusively microbes; No known macrofauna possesses the ability to utilize inorganic...
  
   metabolism is possible, as seen in colorless sulfur bacteria (some Thiobacillus), whereby sulfur compounds such as hydrogen sulfide
  Hydrogen sulfide
  Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...
  
  , elemental sulfur
  Sulfur
  Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
  
  , or thiosulfate
  Thiosulfate
  Thiosulfate is an oxyanion of sulfur. The prefix thio indicates that thiosulfate ion is a sulfate ion with one oxygen replaced by a sulfur. Thiosulfate occurs naturally and is produced by certain biochemical processes...
  
   are oxidized to sulfate. The sulfur compounds serve as electron donors and are consumed to produce ATP
  Adenosine triphosphate
  Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...
  
  . The carbon source for these organisms can be carbon dioxide (autotrophy) or organic carbon (heterotrophy).
  Organoheterotrophy can occur under aerobic
  Aerobic organism
  An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment.Faculitative anaerobes grow and survive in an oxygenated environment and so do aerotolerant anaerobes.-Glucose:...
  
   or under anaerobic
  Aerobic organism
  An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment.Faculitative anaerobes grow and survive in an oxygenated environment and so do aerotolerant anaerobes.-Glucose:...
  
   conditions; lithoautotrophy takes place aerobically.

• Many examples of the genus Euglena
  Euglena
  Euglena is a genus of unicellular flagellate protists. It is the best known and most widely studied member of the phylum Euglenozoa , a diverse group containing some 44 genera and at least 800 species. Species of Euglena are found in fresh and salt waters...
  
  .

External links

• Sanders, Robert W. Mixotrophic Nutrition of Phytoplankton: Venus Fly Traps of the microbial world. Temple University.