From the Guidelines
Bacteria that produce nitrites are primarily nitrifying bacteria, specifically nitrite-oxidizing bacteria (NOB) and ammonia-oxidizing bacteria (AOB). These specialized microorganisms play a crucial role in the nitrogen cycle by converting ammonia to nitrites or nitrites to nitrates. The main genera involved include Nitrosomonas, Nitrosococcus, and Nitrosospira, which oxidize ammonia to nitrites, and Nitrobacter, Nitrospira, and Nitrococcus, which further oxidize nitrites to nitrates 1.
Key Characteristics of Nitrite-Producing Bacteria
- They are chemolithoautotrophs, meaning they derive energy from inorganic chemical reactions rather than organic carbon sources.
- They are commonly found in soil, freshwater, marine environments, and wastewater treatment systems where they help maintain ecosystem balance by preventing toxic ammonia accumulation.
- In agriculture, these bacteria are essential for converting fertilizers into forms usable by plants.
Clinical Significance
Their activity can be measured in clinical settings through nitrite tests, which are useful for detecting urinary tract infections as certain pathogenic bacteria can reduce nitrates to nitrites in urine. However, it's also important to consider the role of nitrites in other contexts, such as in the consumption of processed meats, where nitrites are added as preservatives and can potentially be converted into carcinogenic nitrosamines in the stomach 1.
Conclusion Not Applicable
Instead, focusing on the bacteria themselves, the production of nitrites by nitrifying bacteria is a critical process in both environmental and human health contexts, influencing not only the nitrogen cycle but also the risk of certain diseases when considering dietary factors.
From the Research
Bacteria that Produce Nitrites
- Lactobacilli and bifidobacteria have been shown to generate nitric oxide from nitrite, and some strains can also produce nitrite from nitrate 2, 3, 4
- Escherichia coli can reduce nitrate to nitrite, but it does not accumulate nitrite in the medium, instead reducing it further to ammonia 3, 5
- Other bacteria such as Bacteroides thetaiotaomicron and Clostridium difficile do not produce significant amounts of nitrite or nitric oxide from nitrate or nitrite 4
- The presence of nitrate can induce the production of nitrite and ammonia in some bacteria, such as E. coli and Lactobacillus plantarum 3
Mechanisms of Nitrite Production
- Nitrate-reducing bacteria can convert nitrate to nitrite through enzymatic reduction 3, 6
- Non-enzymatic synthesis can also convert nitrite to nitric oxide, which is a potent bioactive agent with various biological activities 6
- The production of nitrite and nitric oxide can be influenced by factors such as oxygen levels, pH, and the presence of other nutrients 3, 4
Importance of Nitrite-Producing Bacteria
- The production of nitrite and nitric oxide by gut bacteria can have significant effects on host health, including the regulation of blood flow, immune function, and cardiovascular health 2, 6
- An imbalance of nitric oxide in the body may contribute to the development of various diseases, and the production of nitrite and nitric oxide by gut bacteria may play a role in maintaining nitric oxide homeostasis 6