Back to: MICROBIOLOGY 400 LEVEL
Welcome to class!
Hello amazing learner! It’s always a joy to see your bright mind show up for class. Today, we’re moving into a topic that’s all around us—even though we don’t always see it. Whether it’s the vegetables growing on a farm in Kaduna or the fish in the River Niger, life depends on something called biogeochemical cycles, and two of the most important ones are the Carbon and Nitrogen Cycles. Let’s learn how microbes keep these cycles going like the silent heroes they are.
Carbon And Nitrogen Cycles
The Carbon Cycle
Carbon is one of the most important elements in living things. It’s in everything—from the food you eat to the air you breathe. The carbon cycle is the process by which carbon moves through the atmosphere, living organisms, the soil, and water.
How Microbes Help in the Carbon Cycle:
Photosynthesis
Plants, algae, and some bacteria (like cyanobacteria) use carbon dioxide (CO₂) from the air to make food through photosynthesis.
Respiration
Animals and microbes break down food to release energy and give off CO₂ back into the atmosphere.
Decomposition
When plants and animals die, decomposer microbes like Bacillus, Aspergillus, and Pseudomonas break them down, releasing carbon back into the soil and air.
Methanogenesis
In oxygen-free environments like swamps or cow stomachs, some bacteria (called methanogens) produce methane (CH₄), another carbon-containing gas.
The Nitrogen Cycle
Nitrogen is needed for proteins and DNA in all living things, but most of the nitrogen on Earth is in the air as nitrogen gas (N₂), which most organisms can’t use directly. This is where microbes come in!
Steps in the Nitrogen Cycle:
Nitrogen Fixation
Certain bacteria in the soil or in plant roots (like Rhizobium in legumes such as beans and groundnuts) convert N₂ gas into ammonia (NH₃), which plants can use.
Nitrification
Bacteria like Nitrosomonas and Nitrobacter convert ammonia into nitrites (NO₂⁻) and then into nitrates (NO₃⁻), which are absorbed by plants.
Assimilation
Plants use nitrates to build proteins. When animals eat the plants, they also get nitrogen.
Ammonification
When plants and animals die, decomposer microbes return nitrogen to the soil in the form of ammonia.
Denitrification
Some bacteria like Pseudomonas and Clostridium convert nitrates back to nitrogen gas (N₂), which returns to the atmosphere.
Importance in Nigeria and Africa
Farmers in Nigeria benefit from nitrogen-fixing bacteria that enrich the soil naturally, reducing the need for chemical fertilisers.
Wetlands and swamps in areas like Bayelsa support methane-producing microbes important in the carbon cycle.
Proper management of carbon and nitrogen cycles helps in sustainable agriculture and environmental protection.
Summary
- The carbon and nitrogen cycles move essential elements through the environment.
- Microbes play a key role in both cycles.
- In the carbon cycle, microbes help through respiration, decomposition, and methane production.
- In the nitrogen cycle, microbes fix nitrogen, convert ammonia to nitrates, and release nitrogen back into the air.
- Nitrogen-fixing bacteria like Rhizobium are found in legume roots.
- Nitrifying bacteria turn ammonia into nitrates for plants to use.
- Decomposer microbes recycle nutrients from dead organisms.
- Denitrifying bacteria return nitrogen to the atmosphere.
- These cycles are vital for farming, food production, and climate balance.
Evaluation
- What is the role of microbes in nitrogen fixation?
- Name two microbes involved in the carbon cycle and their functions.
- Why are the carbon and nitrogen cycles important for farming in Nigeria?
You’re learning how life stays balanced on Earth, all thanks to these tiny microbial workers. Keep up the great work—Afrilearn is proud to support your journey to greatness. See you in the next lesson!