Ask A Scientist© Molecular Biology Archive

Name       Amanda
status     student
age        12

Question - 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
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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.

PF
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