Which organism is primarily involved in the process of nitrogen fixation in ecosystems?

Bacteria are the primary organisms involved in the process of nitrogen fixation in ecosystems. This process is essential for converting atmospheric nitrogen (N2), which is inaccessible to most living organisms, into ammonia (NH3) or related compounds that can be utilized by plants.

Certain bacteria, particularly those in the genera Rhizobium and Frankia, have a symbiotic relationship with specific plants, such as legumes. These bacteria reside in root nodules of the plants and facilitate nitrogen fixation, allowing the plants to access nitrogen in a form they can assimilate. Other free-living bacteria, like Azotobacter and Clostridium, also play a crucial role in nitrogen fixation by converting atmospheric nitrogen into forms that can be absorbed by plants in the soil.

This process is a vital part of the nitrogen cycle, which is important for maintaining soil fertility and supporting plant growth, ultimately influencing the entire ecosystem. The key role of bacteria in nitrogen fixation highlights their significant contribution to nutrient cycling and ecosystem productivity.