Phylogenetic Tree
Habitat and Diseases
Dr. Volk's Case


Domain: Prokaryotes

Kingdom: Bacteria

Phylum: Firmicutes

Class: Bacilli

Order: Lactobacillales

Family: Streptococcaceae

Genus: Streptococcus

Species: Streptococcus pyogenes

Streptococcus pyogenes is a prokaryote because it is an organism that has no nuclear membrane, no organelles in the cytoplasm except ribosomes, and has its genetic material in the form of single continuous strands forming coils or loops.  Bacteria are unicellular microorganisms.  They are typically a few micrometers long and have many shapes including spheres, rods, and spirals.  Streptococcus pyogenes are classified in the bacteria kingdom because they agree with the conditions of bacteria.  The majority of firmicutes have a gram positive cell wall structure and a cocci or rod shape.  In a gram stain, the Streptococcus pyogenes will be a purple color, indicating that it is a gram positive bacteria.   The class Bacilli is a classification of cocci or rod shaped bacteria, and that is what the Streptococcus pyogenes are.  Lactobacillales are an order of the gram positive bacteria comprising the lactic acid bacteria.  Streptococcus pygenes produces lactic acid, so it is therefore classified under the lactobacillales.  Streptococcaceae are gram positive non-sporulating bacteria including many parasitic, pathogenic and saprophytic forms.  We have already learned that Streptococcus pyogenes is a gram positive bacteria and it also causes many diseases in humans, making it parasitic.  Streptococcus is a genus of spherical, gram positive bacteria, and a member of the phylum Firmicutes.  We have already identified Streptococcus pyogenes under all of the conditions stated for the StreptococcusStreptococci are lactic acid bacteria.  Streptococcus pyogenes is a gram positive cocci that grows in long chains.  Stretptococcus pyogenes displays the group A antigen on its cell wall and beta hemolysis when cultured on blood agar plate.  Streptococcus pyogenes typically produces large zones of beta-hemolysis, which is the complete disruption of erythrocytes and the release of hemoglobin.

Information on this page is from Starr, Mortimer P (The Prokaryotes).

Dividing streptococci (12,000X). Electron micrograph of Streptococcus pyogenes by Maria Fazio and Vincent A. Fischetti, Ph.D. with permission. The Laboratory of Bacterial Pathogenesis and Immunology, Rockefeller University.