Bacteria have existed in the environment from very early since the history of life on Earth. Fossils of bacteria were discovered in rocks dated at least from the Devonian Period, which was more than 300 million years ago. There are also convincing arguments suggesting that bacteria were widespread on Earth about 1.8 billion years ago, at the time when oxygen was believed to have appeared in the atmosphere due to the activities of cyanobacteria.

These factors suggest that bacteria have been in existence in the environment and they even had a lot of time adapting to their environments allowing them an opportunity to give rise to a number of descendant forms.

Let us take a closer look at the reasons why bacteria exist in the environment and the role they play on earth.

The Role of Bacteria on Earth

1. They Prevent the Depletion of Carbon Dioxide

bacteria in the environmentCarbon dioxide is often perceived as a harmful gas that is released into the air when we breathe out. The increased concentration of carbon dioxide in the atmosphere is also a mark of poor air quality.

However, it is important to note that this gas is needed by plants for the process of photosynthesis. This means the unavailability of carbon dioxide could hamper the process of photosynthesis by which plants create energy in the form of sugar and release oxygen in the presence of sunlight. It is one of the key functions of plants which helps in the creation of food.

The process of photosynthesis can occur only in the presence of sunlight and carbon dioxide. This is where the role of bacteria comes in.

Organic carbon that is released into the atmosphere by rotting and dead organisms can quickly deplete the carbon dioxide in the atmosphere in the absence of the activities of bacteria. Bacteria are considered super-decomposers as they have the ability to break down and decompose dead and rotting organisms.

This means the existence of bacteria in the environment supports the process of decomposition thus preventing the quick depletion of carbon dioxide into the atmosphere.

When organisms die, the carbon present in their tissues becomes unavailable for other living beings. Bacteria, by supporting the process of decomposition, can help in the breakdown of these organisms, thereby releasing nutrients including carbon dioxide back into the environment.

This, in turn, can ensure adequate availability of carbon dioxide for  plants for performing photosynthesis. These mechanisms indicate the importance of the existence of bacteria in the atmosphere.

2. They Assist With Sewage Treatment

Bacteria have been important in sewage treatment. The ability of bacteria to break down or decompose unwanted tissues or toxins makes them helpful for clearing waste and supporting sewage treatment.

Some bacteria also help in the breakdown of oil spills and the recovery of precious metals such as gold, palladium, and copper in the mining sector.

The usefulness of bacteria in these activities proves that their existence plays a major role in maintaining the ecosystem.

3. They Support Denitrification

bacteria in the environmentBacteria have played important roles in maintaining the global ecosystem. The ecosystem, on land as well as in the water, has been found to depend heavily on the activities of bacteria. For example; the cycling of nutrients like nitrogen, carbon and sulfur occurs with the help of the ceaseless and continuous activities of some bacteria.

Scientific research has revealed that the cycling of nitrogen is an important activity performed by bacteria in the atmosphere. Plants depend on nitrogen in the soil for their growth. The primary way nitrogen can become available to plants is through the process of nitrogen fixation performed by bacteria, especially Rhizobium, and some cyanobacteria like Anabaena, Spirulina, and Nostoc.

Moreover, some denitrifying bacteria have the ability to metabolize nitrogenous compounds in the reverse direction. This means they can turn nitrates back into nitrogen in the form of gas or nitrous oxide.

These activities of bacteria point to the benefits they offer to plant life. Without the role played by bacteria in nitrogen fixation as well as in the reverse metabolism of nitrogenous compounds, plants would have difficulty surviving. This would deprive humans of essential sources of food, putting their own existence in danger. This marks the importance of the existence of bacteria in the environment.


Bacteria perform numerous functions thus helping humans in an indirect manner. Bacteria also play a role in the survival of plants, and hence, in the survival of human and animal life as well. These benefits point to the importance of the existence of bacteria on the earth.


  • https://ucmp.berkeley.edu/bacteria/bacterialh.html
  • https://en.wikipedia.org/wiki/Bacteria
  • https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8131540/