Chemosynthesis(equation, bacteria, theory)


Chemosynthesis is the process by which certain organisms—most often bacteria—manufacture carbohydrates using chemical energy. In contrast to photosynthesis, which depends on sunlight for energy, chemosynthesis makes use of energy created during inorganic compound-based chemical processes.

This process is frequently encountered in places without sunlight, including deep-sea hydrothermal vents, where hot, mineral-rich fluids from the Earth’s core are discharged into the ocean. Chemosynthetic bacteria are organisms that carry out chemosynthesis. They transform carbon dioxide and water into organic molecules by using the energy released by the oxidation of inorganic substances like hydrogen sulfide or methane.

Since chemosynthesis gives species in these settings a source of energy, it is essential to the maintenance of ecosystems in harsh regions where sunlight is ineffective. Our knowledge of life’s ability to persist on Earth under a variety of harsh environments has increased with the discovery of chemosynthesis.

Chemosynthesis equation

The general equation for chemosynthesis is:

18H2S + 6CO2 + 3O2 → C6H12O6 (carbohydrate) + 12H2O + 18S.

In this equation:

  • represents carbon dioxide.
  • Oxidized inorganic compounds are substances like hydrogen sulfide (H₂S) or methane (CH₄), which serve as the source of chemical energy.
  • Carbohydrates refer to the organic molecules that are produced as a result of chemosynthesis.
  • Water is a product of the overall reaction.
  • Reduced inorganic compounds are the byproducts of the chemical reactions, and they are typically returned to the surrounding environment.

Chemosynthesis is crucial in certain ecosystems, such as deep-sea hydrothermal vent communities, where organisms rely on the energy derived from these chemical reactions to sustain life in the absence of sunlight.

Chemosynthesis bacteria

Microorganisms capable of chemosynthesis, in which carbon dioxide is transformed into organic molecules by using inorganic substances as a source of energy, are known as chemosynthetic bacteria. These bacteria are frequently found in places without sunshine, such as hot springs, some underground habitats, and deep-sea hydrothermal vents.

There are several types of chemosynthetic bacteria, each using different inorganic compounds as an energy source. Here are a few examples:

  1. Sulfur-Oxidizing Bacteria: These bacteria oxidize hydrogen sulfide (H₂S) to obtain energy. The general equation for this process is:


    The energy released in this reaction is used by the bacteria to fix carbon dioxide into organic compounds.

  2. Methane-Oxidizing Bacteria: Some bacteria use methane (CH₄) as their energy source in chemosynthesis. The process involves the oxidation of methane to produce carbon dioxide and water:


    Again, the energy released is used to drive the synthesis of organic molecules.

These bacteria play a critical role in maintaining life in harsh conditions, such the deep sea floor, where sunlight cannot reach. They serve as a source of energy for other creatures in the food chain, forming the foundation of ecosystems in these locations.

Chemosynthesis theory

According to the notion of chemosynthesis, certain organisms may use inorganic substances as a source of energy to generate organic molecules like carbohydrates. Chemosynthesis makes use of the chemical energy obtained from the oxidation of inorganic materials, as opposed to photosynthesis, which depends on sunlight. The first evidence of this mechanism was found in deep-sea habitats, especially in the vicinity of hydrothermal vents, where life thrives in the absence of sunshine.

The key components of the chemosynthesis theory include:

Energy Source: When inorganic substances like hydrogen sulfide (H2S), methane (CH3), or other reduced chemicals oxidize, energy is generated, which is used by chemosynthesis organisms. The synthesis of organic molecules is propelled by the energy derived from these chemical events.

Carbon Fixation: Chemosynthetic organisms fix carbon dioxide (CO₂) into organic molecules in a manner similar to photosynthesis. Carbohydrates, the main energy source and building material for the organisms, are created throughout the process from carbon dioxide.

Harsh habitats: Deep-sea hydrothermal vents, which spew hot, mineral-rich fluids into the ocean, are examples of harsh habitats where sunlight is scarce and chemosynthesis is frequently seen. Additional settings where chemosynthesis takes place are subterranean ecosystems and specific kinds of hot springs.

Function in Ecosystems: In these harsh conditions, chemosynthetic organisms—especially bacteria—are essential to the survival of ecosystems. As the base of the food chain, they give other creatures in the environment a source of energy.

Chemosynthesis has challenged the idea that sunlight is the only source of primary generation in ecosystems, broadening our knowledge of life’s capacity to flourish in a variety of harsh and demanding settings on Earth.

Chemosynthesis example

Deep-sea hydrothermal vent communities provide a well-known example of chemosynthesis. Fissures on the ocean floor that emit hot, mineral-rich fluids are a defining feature of these habitats. These harsh circumstances are ideal for chemosynthesis microorganisms, especially sulfur-oxidizing bacteria, which are the foundation of a distinct ecosystem.

Here’s a simplified example of chemosynthesis in a deep-sea hydrothermal vent:

  1. Energy Source: Hydrogen sulfide (H₂S) is one of the primary inorganic compounds released from the hydrothermal vents. The bacteria use this hydrogen sulfide as an energy source.

  2. Chemosynthetic Reaction: H2S+O2→S+H2O

    This reaction oxidizes hydrogen sulfide, producing sulfur (S) and water (H₂O). The energy released during this process is utilized by chemosynthetic bacteria.

  3. Carbon Fixation: The energy obtained from the oxidation of hydrogen sulfide is used to fix carbon dioxide (CO₂) into organic molecules, typically carbohydrates.

By employing the energy from chemical processes involving inorganic molecules, the entire process produces organic substances. The principal producers in this environment, these chemosynthetic bacteria lay the groundwork for the food chain. Without sunlight, a complex and linked ecosystem is formed by these bacteria, which are essential for the energy demands of other animals in the deep-sea vent community including tube worms and clams.


To sum up, chemosynthesis is an essential biological activity that takes place in dark places like deep-sea hydrothermal vents. The energy from chemical processes involving inorganic materials is used by organisms, especially bacteria, to create organic molecules. This procedure casts doubt on conventional ideas about life’s energy sources and helps preserve unusual ecosystems in harsh settings.

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