The commensal bacterium, Streptococcus mitis is a major coloniser of the oral cavity. This close cousin of Streptococcus pneumoniae has been identified to occupy a range of oral niches independent of pH, epithelial surface and redox state. We have previously observed a high level of genetic diversity in S. mitis with an open pan-genome and only 46 % of the genome identified as core.


We aim to identify the driving force behind the high levels of genetic diversity identified in S. mitis and determine if this diversity can be attributed to oral location.


Samples were collected from the buccal mucosa and tongue dorsum. A total of 75 S. mitis isolates were whole genome and Ion Torrent sequenced and subject to bioinformatic analysis.


In contrast to S. pneumoniae, genetic diversity in S. mitis is predominantly driven by mutation with recombination playing only a minor role. It was also observed that isolates collected from the tongue dorsum were significantly more diverse than those collected from the buccal mucosa. Due to the mutational nature of S. mitis diversity, this suggests varying pressures on S. mitis in these two environments. Study is now underway to establish the genetic differences between S. mitis from these oral niches and determine how this will impact future study and study design of this significant oral microbiome component.

  • This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Article metrics loading...

Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error