Main content
Course: UP Class 12th Biology > Unit 8
Lesson 3: Microbes in sewage treatmentMethanogens and biogas
Overview of microorganisms that produce methane, and their use in biogas production.
This article provides a brief overview of methanogens and their role in biogas production.
Key terms
| term | meaning |
|---|---|
| methanogen | methane-producing microorganism |
| anaerobic | in the absence of oxygen |
| biogas | biofuel mainly consisting of methane |
What is a methanogen?
You might have heard about bacteria and plants that can carry out photosynthesis, during which they produce oxygen. As a result of this ability, they are known as oxygenic organisms. Similarly, a methanogen is a microorganism that produces methane as it carries out its life functions. These microbes usually live in conditions with low or no oxygen available.
One strange, but common, place you might find these creatures is in the guts of herbivores. Animals like cows, sheep, deer, and others that feed primarily on grass and leaves are known as ruminants, and have special digestive systems. These systems rely on microbes to help them break down cellulose from plant matter, since vertebrates do not have the necessary enzyme to do so themselves! Methanogens break down some of the carbon compounds produced during this process, and release methane while doing so.
Other methanogens can be found living in extreme conditions like in hot springs, or in the earth's crust.
Which of the following statements correctly describes methanogens?
How can they be useful to humans?
We saw how methanogens help ruminants out, but what about us humans? It turns out, methanogens can help us with unpleasant, but very important processes!
Methanogens can be used to digest organic matter and thus produce what is known as biogas. In sewage treatment plants (STPs), for example, anaerobic digestion of solid waste is carried out by methanogens. The gases produced by this process - mainly methane and carbon dioxide - are harmful to the environment. Fortunately, they are the main components of biogas.
Biogas can be used as a fuel (or biofuel) for cooking, or to power lighting and other devices. This use is seen especially in rural areas that have a lot of cattle that produce plenty of raw material in the form of dung, or gobar. The image below shows the outer view of a few biogas plants.