Intra-individual variability in nitrate reducing facultative commensal bacteria in the oral cavity

Luke Liddle, Mia Burleigh, Christopher Monaghan, David J. Muggeridge, Nicholas Sculthorpe, John Butcher, Fiona Henriquez, Chris Easton

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The ingestion of nitrate (NO3-)-rich beetroot juice (BRJ) increases the bioavailability of nitric oxide (NO) and, in some cases, has been shown to improve exercise performance. Crucial to this process is the reduction of NO3- in saliva to nitrite (NO2-) by NO3--reducing bacteria in the oral cavity, of which there are fourteen known species. However, the extent to which the abundances of these bacteria vary over time is unknown. The aim of the study was to determine the intra-individual variability (CoVi) in the abundance of known NO3--reducing bacteria in the oral cavity and to assess whether this influences the variance in salivary and plasma [NO2-].

Nine healthy male participants (age 25 ± 5 years, stature 177 ± 5 cm, and body mass 81 ± 11 kg) completed three identical trials. At the beginning of each visit, a bacterial scrape was taken from the posterior section of the dorsal surface of the tongue for 16s rRNA next generation sequencing. During each visit, collection of blood and saliva were obtained at baseline and 2.5 h after the ingestion of BRJ, for later analysis of [NO2-]. Taxonomic classification and bacterial abundance were quantified using Qiime software and clustered based on 97% identity and taxonomy using RDP classifier trained to the GreenGenes database (October 2013 release).

The CoVi for the sum of the NO3--reducing bacteria during the study was 20 %. At the species level, the CoVi for the NO3--reducing bacteria detected in these analyses were: Prevotella Melaninogenica (27 %), Veillonella Dispar (31 %), Rothia Mucilaginosa (41 %), Veillonella Parvula (44 %), Neisseria Subflava (58 %), Haemophilus Parainfluenzae (91 %), and Rothia Dentocariosa (118 %). Salivary and plasma NO2- were all significantly elevated 2.5 h after the ingestion of BRJ in each of the three experimental trials (all P < 0.01). The CoVi for salivary and plasma NO2- following BRJ were 19 and 24%, respectively. The variance in the abundance of NO3- reducing bacteria (sum of all species) was not associated with the variance in salivary or plasma [NO2-].

These data demonstrate that the abundance of NO3--reducing bacteria on the tongue can vary profoundly from week to week. However, such variation in the abundance of these bacteria does not appear to account for the CoVi in plasma and salivary NO markers. Further work is required to determine whether it can influence the physiological and performance responses to BRJ.
Original languageEnglish
Title of host publication23rd Annual Congress of the European College of Sport Science, 4th - 7th July 2018, Dublin - Ireland
Subtitle of host publicationBook of Abstracts
EditorsM. Murphy, C. Boreham, G. De Vito, E. Tsolakidis
Place of PublicationCologne
PublisherEuropean College of Sport Science
Number of pages2
ISBN (Print)978-3-9818414-1-1
Publication statusPublished - 2018
Event23rd Annual Congress of the European College of Sport Science: Sport Science at the Cutting Edge - University College Dublin and Ulster University, Dublin, Ireland
Duration: 4 Jul 20187 Jul 2018 (Conference website)


Conference23rd Annual Congress of the European College of Sport Science
Abbreviated titleECSS 2018
Internet address


Dive into the research topics of 'Intra-individual variability in nitrate reducing facultative commensal bacteria in the oral cavity'. Together they form a unique fingerprint.

Cite this