Metagenomic analysis of nitrate-reducing bacteria in the oral cavity: implications for nitric oxide homeostasis.
Level 5 - mechanism / opinion, no new human data
In vitro biofilm experiments and exploratory bench metagenomics on samples from six volunteers
PubMed 24670812 · doi:10.1371/journal.pone.0088645
What was done
Tongue-scraping samples were collected from six healthy human volunteers to measure microbial nitrate-reducing capacity. Metagenomes of the oral bacterial communities were sequenced and analyzed to identify taxa contributing to nitrate reduction. Additionally, four candidate species were cultivated as single- and mixed-species biofilms to test their nitrate- and nitrite-reduction capabilities in vitro.
What was found
The abstract reports no numerical values. Metagenomic analysis identified 14 candidate species involved in nitrate reduction, including seven species not previously recognized to contribute to this process. In vitro biofilm assays of four candidate isolates demonstrated substantial nitrate- and nitrite-reduction capabilities.
Why it matters
This study identifies specific oral bacterial candidates mediating the human entero-salivary nitrate-nitrite-nitric oxide pathway, clarifying the symbiotic role of oral microbiota in nitric oxide homeostasis.
Limits
The sample size was limited to six healthy human volunteers without demographic or clinical diversity. The abstract does not measure in vivo systemic nitric oxide production, blood pressure, or downstream physiological outcomes.
Cited by
- supports Oral bacteria on the back of the tongue convert dietary nitrates from foods like beets into nitric oxide.