Streptococcus sobrinus
Streptococcus sobrinus is a Gram-positive
Gram-positive bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink...

, catalase-negative, non-motile, and anaerobic
Anaerobic is a word which literally means without oxygen, as opposed to aerobic.In wastewater treatment the absence of oxygen is indicated as anoxic; and anaerobic is used to indicate the absence of a common electron acceptor such as nitrate, sulfate or oxygen.Anaerobic may refer to:*Anaerobic...

  member of the genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

Streptococcus is a genus of spherical Gram-positive bacteria belonging to the phylum Firmicutes and the lactic acid bacteria group. Cellular division occurs along a single axis in these bacteria, and thus they grow in chains or pairs, hence the name — from Greek στρεπτος streptos, meaning...



S. sobrinus in conjunction with the closely related species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 Streptococcus mutans
Streptococcus mutans
Streptococcus mutans is a facultatively aerobic, Gram-positive coccus-shaped bacterium commonly found in the human oral cavity and is a significant contributor to tooth decay.The microbe was first described by J Kilian Clarke in 1924.-Introduction:...

are pathogenic within humans and enhances the formation of caries
Caries is a progressive destruction of any kind of bone structure, including the skull, ribs and other bones, or the teeth. Caries can be caused by osteomyelitis, which is a microorganism disease. A disease that involves caries is mastoiditis, an inflammation of the mastoid process, in which the...

  within teeth. Biofilm
A biofilm is an aggregate of microorganisms in which cells adhere to each other on a surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance...

 from the mixture of sugar and plaque
Dental plaque
Dental plaque is a biofilm, usually a pale yellow, that develops naturally on the teeth. Like any biofilm, dental plaque is formed by colonizing bacteria trying to attach themselves to a smooth surface...

 create a suitable environment for S. sobrinus to grow. S. sobrinus is more closely connected than S. mutans with the prevalence of caries. S. sobrinus is also affiliated with early childhood caries, which are responsible for the majority of dental abscesses and toothaches in children. Children generally acquire S. sobrinus strains from their mother, but the relatively high consumption of sugars by minors facilitates bacterial growth and threatens the onset of early childhood tooth decay. S. sobrinus has also been documented within the teeth of rats
RATS may refer to:* RATS , Regression Analysis of Time Series, a statistical package* Rough Auditing Tool for Security, a computer program...



S. sobrinus was discovered by the French biologist Louis Pasteur
Louis Pasteur
Louis Pasteur was a French chemist and microbiologist born in Dole. He is remembered for his remarkable breakthroughs in the causes and preventions of diseases. His discoveries reduced mortality from puerperal fever, and he created the first vaccine for rabies and anthrax. His experiments...

 in 1887 along with other human pathogens. The full genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....

 of S. sobrinus has been yet to be sequenced, although the related strand S. mutans has been fully sequenced.


In cell biology, molecular biology and related fields, the word extracellular means "outside the cell". This space is usually taken to be outside the plasma membranes, and occupied by fluid...

 long-chained glucans synthesized from sucrose
Sucrose is the organic compound commonly known as table sugar and sometimes called saccharose. A white, odorless, crystalline powder with a sweet taste, it is best known for its role in human nutrition. The molecule is a disaccharide composed of glucose and fructose with the molecular formula...

 via glucosyltransferase enzymes help accumulate S. sobrinus on tooth enamel
Tooth enamel
Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...

 surfaces. The glucans provide a shelter for bacterial colonization, and the protected environment creates the perfect nesting ground for S. sobrinus and other microorganisms to sustain a stable community in the form of dental plaque. S. sobrinus in turn releases lactic acid
Lactic acid
Lactic acid, also known as milk acid, is a chemical compound that plays a role in various biochemical processes and was first isolated in 1780 by the Swedish chemist Carl Wilhelm Scheele. Lactic acid is a carboxylic acid with the chemical formula C3H6O3...

 in the anaerobic metabolism of glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

. Lactic acid demineralizes tooth enamel and fosters the initiation of dental caries. S. sobrinus has an optimal growth temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

 of 37°C and thrives in a slightly acidic environment at a pH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

 of 6.3. This makes the human mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....

 a suitable habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

 due to its acidic characteristics, favorable body temperature, and significant amount of food sugars passing through the mouth on a daily basis. However, these traits also indicate that S. sobrinus has a difficult time surviving outside the host of the human teeth.


In 1995 a paper by Meurman et al. tested Lactobacillus
Lactobacillus is a genus of Gram-positive facultative anaerobic or microaerophilic rod-shaped bacteria. They are a major part of the lactic acid bacteria group, named as such because most of its members convert lactose and other sugars to lactic acid. They are common and usually benign...

rhamnosus for inhibitory properties, although this relationship was only observed with a weak correlation at a pH below 5. Lectin
Lectins are sugar-binding proteins that are highly specific for their sugar moieties. They play a role in biological recognition phenomena involving cells and proteins. For example, some viruses use lectins to attach themselves to the cells of the host organism during infection...

 from Talisia esculenta
Talisia esculenta
Talisia esculenta is a medium-sized tree native to the Amazon Basin, and is found in Brazil, Colombia, Peru, Paraguay and Bolivia.The tree and fruit are called pitomba in English, Spanish and Portuguese, cotopalo in Spanish, pitoulier comestible in French and olho de boi, pitomba-rana and pitomba...

and Labramin from Labramia bojeri seeds were found to inhibit the adherence of S. sobrinus to tooth enamel, but had no effect the growth of the population itself. A study by Sun et al. in 2009 tested a vaccine for S. sobrinus, and initial tests have been successful in providing protection.
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