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The superpower of bacteria: How do they convert nitrogen in the air into nutrients for plants?
In our lives, there are some things that are often overlooked, yet they affect life on earth all the time and everywhere. Nitrogen, as an element commonly found in nature, is of self-evident importance for plant growth. What is amazing is how this nitrogen, which cannot be directly used by plants, is converted into the nutrients they need. Bacteria play an indispensable role behind this process.
Basic introduction to the nitrogen cycle
The nitrogen cycle is the biogeochemical conversion of nitrogen into various chemical forms in the atmosphere, terrestrial and marine ecosystems. Although 78% of Earth's atmosphere is nitrogen, it is not in a form that plants can directly use. Therefore, the effective utilization of nitrogen depends largely on the conversion of microorganisms.
Nitrogen fixation
In the first step of the nitrogen cycle, nitrogen gas (N2) must be converted into nitrate (NO3) or nitrite (NO2), a process called nitrogen fixation. Nitrogen fixation in nature is mainly carried out by some microorganisms called nitrogen-fixing bacteria, which have enzymes that can convert nitrogen gas into ammonia. In fact, about 500 to 1000 million kilograms of nitrogen are fixed by lightning each year, but most of the nitrogen fixation is carried out by these free-living or symbiotic bacteria.
Nitrogen fixation is an extremely important process in nature. Through the efforts of these bacteria, nitrogen can be converted into a form that plants can use, further promoting plant growth.
Nitrogen assimilation
Plant roots can absorb nitrates or ammonium ions from the soil. In this process, nitrate is first converted into nitrite and then into ammonium ions, which are important raw materials for the amino acids, nucleic acids and chlorophyll needed by plants.
Amination
When plants or animals die, or when animals produce waste, nitrogen is initially present in organic form. As bacteria or fungi act, this organic nitrogen is converted into ammonium (NH4+), a process called ammonification or mineralization. During this process, several enzymes play an important role, helping to convert organic nitrogen into a form that is usable by plants. "This process allows the organism to recycle nutrients."
Nitrification
Nitrification is the process of converting ammonium into nitrates, which is mainly carried out by specific bacteria in the soil. First, ammonia is oxidized by certain bacteria into nitrites, which are then further converted into nitrates. Through this series of conversions, ammonia is converted into non-toxic nitrates that can be safely absorbed by plants.
Denitrification
When the nitrogen cycle is about to be completed, denitrification converts nitrates into nitrogen gas. This process mainly occurs in an anaerobic environment and is responsible for some specific bacteria. These bacteria use nitrate as a respiratory electron acceptor, converting it into nitrogen gas that cannot be used by plants, allowing the nitrogen cycle to operate completely.
Human influence on the nitrogen cycle
Human activities, such as overuse of fertilizers and industrial emissions, have significantly altered the global nitrogen cycle. Such changes not only affect the health of natural ecosystems, but also have a negative impact on human health. As human demand for nitrogen increases, the balance of this cycle is being challenged.
"While bacteria play an impressive role in transforming nitrogen, are we inadvertently disrupting this natural balance?"
Conclusion
The bacteria's superpowers allow atmospheric nitrogen to be converted into nutrients that plants need, which not only supports plant growth but also promotes the health of the entire ecosystem. However, with the impact of climate change and human activities, the future of this cycle still faces severe challenges. Can we find sustainable ways to manage and use this natural resource in ways that protect life and the environment on Earth?
