''Streptococcus salivarius'' is a species of

spherical A sphere (from Ancient Greek, Greek , ) is a surface (mathematics), surface analogous to the circle, a curve. In solid geometry, a sphere is the Locus (mathematics), set of points that are all at the same distance from a given point in three ...

gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. The Gram stain is ...

lactic acid bacteria Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical ( cocci) bacteria that share common metabolic and physiological characteristics. These bact ...

that is both

catalase Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting ...

and

oxidase In biochemistry, an oxidase is an oxidoreductase (any enzyme that catalyzes a redox reaction) that uses dioxygen (O2) as the electron acceptor. In reactions involving donation of a hydrogen atom, oxygen is reduced to water (H2O) or hydrogen peroxid ...

negative. ''S. salivarius'' colonizes (usually in chains) the

oral cavity A mouth also referred to as the oral is the body orifice through which many animals ingest food and vocalize. The body cavity immediately behind the mouth opening, known as the oral cavity (or in Latin), is also the first part of the alime ...

and

upper respiratory tract The respiratory tract is the subdivision of the respiratory system involved with the process of conducting air to the alveoli for the purposes of gas exchange in mammals. The respiratory tract is lined with respiratory epithelium as respiratory ...

of humans just a few hours after birth, making further exposure to the bacteria harmless in most circumstances. The bacterium is considered an opportunistic pathogen, rarely finding its way into the bloodstream, where it has been implicated in cases of

sepsis Sepsis is a potentially life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage of sepsis is followed by suppression of the immune system. Common signs and s ...

in people with

neutropenia Neutropenia is an abnormally low concentration of neutrophils (a type of white blood cell) in the blood. Neutrophils make up the majority of circulating white blood cells and serve as the primary defense against infections by destroying bacteria ...

, (a deficiency in white blood cells). ''S. salivarius'' has distinct characteristics when exposed to different environmental nutrients. For example, in the laboratory, if a

growth medium A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Differe ...

is used that includes

sucrose Sucrose, a disaccharide, is a sugar composed of glucose and fructose subunits. It is produced naturally in plants and is the main constituent of white sugar. It has the molecular formula . For human consumption, sucrose is extracted and refined ...

then ''S. salivarius'' is able to use the sucrose to produce a capsule around itself. However, if sucrose is replaced by

glucose Glucose is a sugar with the Chemical formula#Molecular formula, molecular formula , which is often abbreviated as Glc. It is overall the most abundant monosaccharide, a subcategory of carbohydrates. It is mainly made by plants and most algae d ...

as on a GYC (glucose, yeast extract, calcium carbonate) plate, ''S. salivarius'' is unable to make a capsule from the 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 reacts with the calcium carbonate in the GYC plate, resulting in zones of clearings on the plat

Role as a probiotic

Some strains of ''S. salivarius'' are being trialed for their use as a

probiotic Probiotics are live microorganisms that provide health benefits when consumed, generally by improving or restoring the microbiota in the gut. Probiotics are considered generally safe to consume, but may cause bacteria– host interactions ...

in the

prevention Prevention may refer to: Health and medicine * Preventive healthcare, measures to prevent diseases or injuries rather than curing them or treating their symptoms General safety * Crime prevention, the attempt to reduce deter crime and crimin ...

of oral infections. Some strains of ''S. salivarius'' are found to produce BLIS (

Bacteriocin Bacteriocins are proteinaceous or peptide, peptidic toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strain(s). They are similar to yeast and paramecium killing factors, and are structurally, functionally ...

-like Inhibitory Substances) which are antimicrobial peptides. These peptides display interspecies inhibition, and inhibit ''

Streptococcus pyogenes ''Streptococcus pyogenes'' is a species of Gram-positive, aerotolerant bacteria in the genus '' Streptococcus''. These bacteria are extracellular, and made up of non-motile and non-sporing cocci (round cells) that tend to link in chains. They ...

'' (which causes

strep throat Streptococcal pharyngitis, also known as streptococcal sore throat (strep throat), is pharyngitis (an infection of the pharynx, the back of the throat) caused by ''Streptococcus pyogenes'', a Gram-positive bacteria, gram-positive, group A str ...

infections). Lozenges containing S. salivarius are marketed to support immunity against more virulent Streptococcus strains. People with this strain of naturally occurring ''S. salivarius'' on their tongue have been shown to have fewer Strep throat infections. This is also being investigated for its potential to prevent

rheumatic heart disease Valvular heart disease is any cardiovascular disease process involving one or more of the four valves of the heart (the aortic and mitral valves on the left side of heart and the pulmonic and tricuspid valves on the right side of heart). The ...

which is also caused by ''S. pyogenes.''

Agglutination In linguistics, agglutination is a morphology (linguistics), morphological process in which words are formed by stringing together morphemes (word parts), each of which corresponds to a single Syntax, syntactic feature. Languages that use agglu ...

of ''Streptococcus salivarius'' is often used in the diagnosis of

atypical pneumonia Atypical pneumonia, also known as walking pneumonia, is any type of pneumonia not caused by one of the pathogens most commonly associated with the disease. Its clinical presentation contrasts to that of "typical" pneumonia. A variety of microorga ...

caused by ''

Haemophilus influenzae ''Haemophilus influenzae'' (formerly called Pfeiffer's bacillus or ''Bacillus influenzae'') is a Gram-negative, Motility, non-motile, Coccobacillus, coccobacillary, facultative anaerobic organism, facultatively anaerobic, Capnophile, capnophili ...

Subspecies

Streptococcus thermophilus ''Streptococcus thermophilus'' formerly known as ''Streptococcus salivarius ''subsp.'' thermophilus'' is a gram-positive bacteria, gram-positive bacterium, and a lactic acid fermentation, fermentative facultative anaerobic organism, facultative ...

'' was originally described as a subspecies of this entry, ''Streptococcus salivarius'' subsp. ''thermophilus''. It has since been promoted to the species rank. The FastANI metric used by GTDB concurs with this decision.

References

External links

''Streptococcus salivarius''

UniProt UniProt is a freely accessible database of protein sequence and functional information, many entries being derived from genome sequencing projects. It contains a large amount of information about the biological function of proteins derived fro ...

Type strain of ''Streptococcus salivarius'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
Gram-positive bacteria Streptococcaceae Bacteria described in 1906 {{lactobacilli-stub

Role as a probiotic

Subspecies

References

Further reading

External links