desnitrificação

Desnitrification is a biological process where nitrate (NO3−) is reduced to nitrogen gas (N2) by microorganisms. This process is crucial in various ecosystems, particularly in aquatic environments and soils. Desnitrification is primarily carried out by bacteria, such as those belonging to the genus Pseudomonas and Paracoccus, which use nitrate as a terminal electron acceptor in their respiratory chain.

The process of desnitrification involves several steps. First, nitrate is reduced to nitrite (NO2−) by nitrate-reducing bacteria. This step is often followed by the reduction of nitrite to nitric oxide (NO) by nitrite-reducing bacteria. Finally, nitric oxide is reduced to nitrogen gas by nitric oxide-reducing bacteria. The overall reaction can be represented as:

2 NO3− + 10 e− + 12 H+ → N2 + 6 H2O

Desnitrification plays a significant role in nitrogen cycling, as it helps to remove nitrate from the environment, preventing eutrophication and maintaining water quality. However, excessive desnitrification can lead to the production of nitrous oxide (N2O), a potent greenhouse gas. Therefore, understanding and managing desnitrification processes are important for environmental conservation and sustainable management of nitrogen resources.

In agricultural soils, desnitrification can be influenced by various factors, including soil moisture, temperature, and the presence of organic matter. In aquatic systems, desnitrification rates can be affected by factors such as light intensity, pH, and the availability of alternative electron acceptors.