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Streptolysin O is an oxygen-sensitive cytotoxin, secreted by most group A Streptococcus (GAS), and interacts with cholesterol in the membrane of eukaryotic cells (mainly red and white blood cells, macrophages, and platelets), and usually results in beta-hemolysis under the surface of blood agar.
Bacterial cellular morphologies are the shapes that are characteristic of various types of bacteria and often key to their identification. Their direct examination under a light microscope enables the classification of these bacteria (and archaea). Generally, the basic morphologies are spheres (coccus) and round-ended cylinders or rod shaped ...
Bacteria are ubiquitous, living in every possible habitat on the planet including soil, underwater, deep in Earth's crust and even such extreme environments as acidic hot springs and radioactive waste. [24] [25] There are thought to be approximately 2×10 30 bacteria on Earth, [26] forming a biomass that is only exceeded by plants. [27]
Non-cellular life, also known as acellular life, is life that exists without a cellular structure for at least part of its life cycle. [1] Historically, most definitions of life postulated that an organism must be composed of one or more cells, [2] but, for some, this is no longer considered necessary, and modern criteria allow for forms of life based on other structural arrangements.
Rosenbach 1884. 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 are clinically important for humans, as they are an infrequent, but usually pathogenic, part of ...
In most bacteria the most numerous intracellular structure is the ribosome, the site of protein synthesis in all living organisms. All prokaryotes have 70S (where S= Svedberg units) ribosomes while eukaryotes contain larger 80S ribosomes in their cytosol. The 70S ribosome is made up of a 50S and 30S subunits.
Streptococcus pneumoniae, or pneumococcus, is a Gram-positive, spherical bacteria, alpha-hemolytic member of the genus Streptococcus. [1] S. pneumoniae cells are usually found in pairs (diplococci) and do not form spores and are non motile. [2] As a significant human pathogenic bacterium S. pneumoniae was recognized as a major cause of ...
Lehmann and Neumann, 1896. Streptococcus agalactiae (also known as group B streptococcus or GBS) is a gram-positive coccus (round bacterium) with a tendency to form chains (as reflected by the genus name Streptococcus). It is a beta- hemolytic, catalase -negative, and facultative anaerobe. [1][2]