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16S rRNA RefSeq: V15.22    Genomic RefSeq: V9.15
Genus: Streptococcus
Lineage: Bacteria;Firmicutes;Bacilli;Lactobacillales;Streptococcaceae;Streptococcus
Overview: Streptococci are among the most abundant bacteria in the mouth, making up 30-60% of the bacteria on the buccal mucosa and 15-30% of the bacteria on the tongue dorsum and in supragingival plaque.

Ecological role/importance in health and disease: The 37 species of Streptococcus listed in HOMD include many members of the healthy commensal microbiota as well as several that are pathogens and one that is used to produce yogurt (S. thermophilus). Streptococci such as S. mitis and S. gordonii are among the first bacteria to colonize the tooth surface after it is cleaned, where they begin the process of ecological succession (Diaz et al. 2006). S. salivarius is abundant on the tongue dorsum and can carry out nitrate reduction to nitrite, thereby participating in the physiology of its human host (Hezel and Weitzberg 2013). Other streptococci that are usually rare in the healthy mouth can cause disease, such as S. mutans, which is associated with dental caries, S. pyogenes, which causes strep throat, and S. pneumoniae, which can cause pneumonia. In the subgingival plaque biofilm, most streptococci are grouped into the "yellow complex", but S. constellatus is a member of the "orange complex" marking part of the ecological succession from health toward periodontitis (Socransky et al. 1998).
eHOMD Taxonomy
LifeCellular Organisms
 DomainBacteria (788) Abundance
  PhylumFirmicutes (255) Abundance
   ClassBacilli (104) Abundance
    OrderLactobacillales (75) Abundance
     FamilyStreptococcaceae (38) Abundance
      GenusStreptococcus (37) Abundance
       Species       Streptococcus agalactiae (HMT-537) Abundance
       Streptococcus anginosus (HMT-543) Abundance
       Streptococcus australis (HMT-073) Abundance
       Streptococcus constellatus (HMT-576) Abundance
       Streptococcus cristatus
       Streptococcus downei (HMT-594) Abundance
       Streptococcus gordonii (HMT-622) Abundance
       Streptococcus infantis
       Streptococcus intermedius (HMT-644) Abundance
       Streptococcus lactarius (HMT-948) Abundance
       Streptococcus mitis (HMT-677) Abundance
       Streptococcus mutans (HMT-686) Abundance
       Streptococcus oralis
       Streptococcus parasanguinis
       Streptococcus peroris (HMT-728) Abundance
       Streptococcus pneumoniae (HMT-734) Abundance
       Streptococcus pyogenes (HMT-745) Abundance
       Streptococcus salivarius (HMT-755) Abundance
       Streptococcus sanguinis (HMT-758) Abundance
       Streptococcus sinensis (HMT-767) Abundance
       Streptococcus sobrinus (HMT-768) Abundance
       Streptococcus sp._HMT_056 (HMT-056) Abundance
       Streptococcus sp._HMT_057 (HMT-057) Abundance
       Streptococcus sp._HMT_061 (HMT-061) Abundance
       Streptococcus sp._HMT_064 (HMT-064) Abundance
       Streptococcus sp._HMT_066 (HMT-066) Abundance
       Streptococcus sp._HMT_074 (HMT-074) Abundance
       Streptococcus sp._HMT_423 (HMT-423) Abundance
       Streptococcus thermophilus (HMT-152) Abundance
       Streptococcus vestibularis (HMT-021) Abundance