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Name: Amanda
Status: Student
Age: 12
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What's the taxonomy of the bacteria streptoccocus?

When you ask a microbiologis about the taxonomy of an organism, you will get a list of organisms that are closely related to the one you ask for. The relation could be described like a tree: The further down the branches, the more refined are the differences between the organisms listed. For instance, with Streptococci, we start at the big branch Bacteria (they are not animals, or plants), they belong to the Bacillus/Clostridium group (this is moving a few branches down, but all bacteria within this big branch are still pretty different), then Streptococcus is the genus (we're approaching a branch where all bacteria look rather similar now). Here is how to simply describe the genus:

The genus Streptococcus (plural streptococci) is a collection of round bacteria (cocci means round) that grow best in an atmosphere with little oxygen (micro aerobic. The bacteria are called micro aerophilic because they 'like a little oxygen'). They are Gram-positive, which is a classical microbiological stain that determines wheather the bacteria have one, or two membranes around them. Streptococci have one, which results in a 'positive' stain. They can not swim, and grow in chains or in pairs. That is how you would recognize them under the microscope.

The genus can be further branched into 40 species, which all have the abovementioned characteristics, but they differ in details. Most famous is S. pyogenes.

Most Streptococci are pathogenic which means they can cause disease. Some are transmitted in food, others by water droplets (caughing). Streptococcus pyogenes causes sore throat and scarlet fever, sometimes more dangerous diseases. Their nickname is 'flesh-eating bacteria', but this serious disease is not common. Many people carry streptococci in their mouth and throat without complaints.

Trudy Wassenaar
curator of the Virtual Museum of Bacteria

I'll guess it in the genus Streptococci, it is a non-motile (does not move) gram positive (penicillin sensitive) coccus which is of course a well known pathogen.


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