Related Experiment Video
Updated: Aug 15, 2026

Preparation of Rat Skeletal Muscle Homogenates for Nitrate and Nitrite Measurements
Published on: July 29, 2021
Gastrointestinal bacteria generate nitric oxide from nitrate and nitrite
T Sobko1, C I Reinders, E Jansson
1Department of Physiology and Pharmacology, Karolinska Institutet, S-17177 Stockholm, Sweden.
Abstract:
Denitrifying bacteria in soil generate nitric oxide (NO) from nitrite as a part of the nitrogen cycle, but little is known about NO production by commensal bacteria. We used a chemiluminescence assay to explore if human faeces and different representative gut bacteria are able to generate NO. Bacteria were incubated anaerobically in gas-tight bags, with or without nitrate or nitrite in the growth medium. In addition, luminal NO levels were measured in vivo in the intestines in germ-free and conventional rats, and in rats mono-associated with lactobacilli. We show that human faeces can generate NO after nitrate or nitrite supplementation. Lactobacilli and bifidobacteria generated much NO from nitrite, but only a few of the tested strains produced NO from nitrate and at much lower levels. In contrast, Escherichia coli, Bacteroides thetaiotaomicron, and Clostridium difficile did not produce significant amounts of NO either with nitrate or nitrite. NO generation in the gut lumen was also observed in vivo in conventional rats but not in germ-free rats or in rats mono-associated with lactobacilli. We conclude that NO can be generated by the anaerobic gut flora in the presence of nitrate or nitrite. Future studies will reveal its biological significance in regulation of gastrointestinal integrity.
Related Concept Videos
Nitric Oxide Signaling Pathway
Bacterial Flora of the Large Intestine
The normal gut flora of the colon plays a critical role in generating essential vitamins such as vitamins K, B5, and B7.
Overview of Nitrogen Metabolism
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this nitrogen...
Microbes and the Nitrogen Cycle
Inorganic Nitrogen Assimilation
Functions of the Gut Microbiota

