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Autotrophic organisms: what are they, characteristics and examples

Not all living organisms obtain the energy and nutrients necessary to carry out their biological functions from the same sources, but they have developed different aptitudes to be able to synthesize their forms of energy from the carbon present in the environment. One of the forms of nutrition existing among organisms is the so-called autotrophy.

In this AgroCorrn article the subject of autotrophic organisms will be discussed : what they are, characteristics and examples . Keep reading if you are interested in learning more about these organisms on which a large part of the food chains in ecosystems are based.

What are autotrophic organisms

The autotrophic organisms (from the Greek “autos” = “self” and “trophos” = “feed”) are those that have the ability to obtain energy and nutrients from inorganic matter and do so either by sunlight, through a process called photosynthesis, or through oxidative processes of inorganic compounds in a process known as chemosynthesis.

Thus, autotrophic organisms do not need to feed on other living beings to obtain energy, although they are consumed by these for that purpose (primary consumers), which makes them primary producers in the food web. In this other article we talk about What are food webs and examples .

Characteristics of autotrophic organisms

Autotrophic organisms are characterized by carrying out anabolic processes of synthesis of complex compounds from simpler molecules. To obtain energy, autotrophic organisms convert the inorganic carbon in the environment into organic compounds through a process known as “carbon fixation” , which has several types. Depending on how they obtain energy, autotrophic organisms can be either phototrophic or chemoautotrophic .

Autotrophic organisms: phototrophs

These generate their own food from sunlight (which plants and algae capture through organelles called chloroplasts, where the pigment chlorophyll is found, which gives them a greenish color), carbon dioxide (inorganic form of carbon) and water. , with those that form sugars that they use as a source of energy, in a process called photosynthesis.

Thus, through photosynthesis, they convert the energy of light, CO2 and mineral salts into highly energetic rich organic compounds (glucose) and oxygen that they release into the atmosphere (except in the case of bacteria that carry out anoxygenic photosynthesis, in there is no such production of O2). That is, the product resulting from photosynthesis is glucose, which they use to obtain energy, in respiration, and also to synthesize starch and cellulose, a structural component of the cell wall.

Learn here the Difference between photosynthesis and plant respiration .

Autotrophic organisms: chemotrophs

Chemotrophic organisms, on the other hand, use other chemical substances as an energy source, such as hydrogen sulphide, sulfur, ammonium or ferrous iron, in the chemosynthesis process.

Within the food web, autotrophic organisms play the important role of “primary producers” , which are those that serve as a food source for heterotrophic organisms, also known as “consumers”.

Examples of autotrophic organisms

There are representatives of autotrophic organisms in both terrestrial and aquatic environments. Some examples of autotrophic organisms are all plants, certain types of bacteria, archaea, and protists (such as algae), which play fundamental roles in the food chains of all types of ecosystems. These are some clear examples:

  • The set of plants is characterized by autotrophy, as is the case of the sunflower ( Helianthus annuus ) or the common fir ( Abies alba ).
  • Other examples of autotrophic organisms are cyanobacteria , the only protist organisms capable of oxygenic photosynthesis. Some known genera of cyanobacteria are Nostoc or Gloetrichia.
  • Algae are also autotrophic organisms, with representatives of the genera Euglena or Ceratum.
  • Among the photoautotrophic bacteria that carry out anoxygenic photosynthesis, some species of purple bacteria can be distinguished, such as Rhodospirillum rubrum or Rhodobacter spaeroides, sulfurous red bacteria such as Chromatium winesum , sulfurous green bacteria such as Pelodictyon clathratiforme, and non-sulfurous bacteria such as Chloronema sp.
  • In the group of chemoautotrophic organisms , iron oxidizing bacteria stand out (such as Thiobacillus ferrooxidans ) which, as mentioned above, obtain their energy and sustenance from the oxidation of inorganic compounds in the environment, which is usually rich in iron.
  • Other chemoautotrophic bacteria are the so-called sulfur bacteria (such as Thiobacillus thiooxidans ), which live in areas of accumulation of pyrite (sulfur mineral), on which they feed.
  • Other examples of chemoautotrophy occur in nitrogen bacteria , that is, they take part in the nitrogen cycle, such as those of the Nitrosomonas or Nitrobacter genera , among others, as well as in hydrogen bacteria .

After knowing that among autotrophic organisms there are algae and plants, among others, we offer you more information about Similarities and differences between plants and algae .

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