|Colony of Streptococcus salivarius on blood agar|
Andrewes & Horder 1906
Streptococcus salivarius subsp. thermophilus Andrewes & Horder 1906
Streptococcus salivarius is a species of spherical, Gram-positive bacteria which colonize the mouth and upper respiratory tract of humans a few hours after birth, making further exposure to the bacteria harmless. The bacteria is considered an opportunistic pathogen, rarely finding its way into the bloodstream, where it has been implicated in septicemia cases in people with neutropenia.
S. salivarius has distinct characteristics when exposed to different environmental nutrients. For example, in the laboratory, if a SYTA plate is used, then S. salivarius is able to use the sucrose in the SYTA plate to produce a capsule around itself. However, if grown on GYC plate, with no sucrose, instead only glucose, then S. salivarius is not able to make a capsule from glucose.
More importantly, in the laboratory, S. salivarius can show a distinct clearing on GYC plates. This is because S. salivarius can ferment the glucose yielding lactic acid. Next, the lactic acid actually reacts with the calcium carbonate in the GYC plate, resulting in zones of clearings on the plate.
Role as a probiotic
Some strains of S. salivarius are being trialed for their use as a probiotic in the prevention of oral infections. Some strains of S. salivarius are found to produce BLIS (Bacteriocin-like Inhibitory Substances) which is an antimicrobial peptide. This peptide displays interspecies inhibition, and inhibits Streptococcus pyogenes (which causes Strep throat infections). People with this strain of naturally occurring S. salivarius on their tongue have been shown to have less Strep throat infections. This is also being investigated for its potential to prevent rheumatic heart disease which is also caused by S. pyogenes.
Since 1995, the subspecies Streptococcus salivarius subs. thermophilus is a synonym of the species Streptococcus thermophilus.
So, the only subspecies Streptococcus salivarius subs. salivarius become a synonym of the species Streptococcus salivarius.
- Wescombe, P. A., N. C. K. Heng, et al. (2009). "Streptococcal bacteriocins and the case for Streptococcus salivarius as model oral probiotics." Future Microbiology 4(7): 819-835.
- Streptococcus salivarius at National Center for Biotechnology Information (NCBI)
- Streptococcus salivarius, UniProt
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