Chemosynthesis is the process that ensures the production of organic compounds independently of light energy. This biological process is carried out, for example, by some microorganisms that live in the depths of the ocean, where there is no sunlight.

Due to the ability to produce organic compounds, organisms that carry out chemosynthesis, as well as those that carry out photosynthesis, are called autotrophs.

Autotrophs and Heterotrophs

Summary on chemosynthesis

  • It is a process in which inorganic compounds are used as an energy source for the production of organic compounds.
  • It does not need solar energy, as in photosynthesis.
  • It is an important process for the maintenance of the food chain in hydrothermal vents.
  • It does not, however, only occur in organisms that live in extreme environments. Nitrifying bacteria also carry out this process.
  • Chemosynthetic organisms are autotrophic organisms.

What is chemosynthesis?

Chemosynthesis is a biological process that ensures the production of organic compounds and is independent of energy from sunlight . It is carried out mainly by bacteria , among which we can mention the nitrobacteria and ferrobacteria.

The energy for carrying out chemosynthesis comes from the oxidation of reduced inorganic compounds that contain nitrogen , sulfur or iron or from the oxidation of hydrogen gas.

The process takes place in two steps :

  • In the first step, oxidation of the inorganic substance occurs , which will promote the release of protons and electrons and the formation of NADPH and ATP .
  • In the second stage, there is the incorporation of carbon dioxide to obtain carbon and the production of organic substances.

Are chemosynthetic organisms autotrophs or heterotrophs?

Autotrophic organisms are those capable of producing their own food, that is, they synthesize the organic matter they need without ingesting other organisms or substances derived from other living beings.

Like organisms that perform photosynthesis, those that perform chemosynthesis are capable of producing their own organic compounds, and are therefore considered autotrophic organisms .


Like photosynthesis,It is a process that promotes the primary production of organic compounds . Its importance can be evidenced when we analyze, for example, communities that live in hydrothermal vents in the oceanic depths. Sunlight does not reach these locations, which makes photosynthesis impossible.

However, chemosynthetic organisms are able to extract energy through the oxidation of inorganic molecules and produce organic compounds. The energy that sustains these ecosystems , therefore, is found in minerals and chemical compounds. Chemosynthesis, in these environments, is the most important and life-sustaining primary production process in environments without lighting .

Chemosynthesis, however, does not only occur in organisms that live in extreme environments . Nitrifying bacteria, belonging to the genera Nitrosomonas and Nitrobacter, are examples of bacteria that perform chemosynthesis. They oxidize ammonia ( Nitrosomonas ) and nitrite ( Nitrobacter ) and ensure the energy needed to fix carbon dioxide.

Chemosynthesis and Photosynthesis

Photosynthetic organisms use solar energy to produce their organic compounds.

As we have seen throughout the text, chemosynthesis is a process in which an organism produces organic compounds using the energy obtained through the oxidation of inorganic substances. On the other hand, organisms that do photosynthesis get the energy they need to produce organic compounds from sunlight . Despite this difference, the two processes use carbon dioxide as a carbon source for the production of sugars.

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