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When alpha-hemolysis (α-hemolysis) is present, the agar under the colony is light and greenish. Streptococcus pneumoniae and a group of oral streptococci (Streptococcus viridans or viridans streptococci) display alpha-hemolysis. This is sometimes called green hemolysis because of the color change in the agar.
A red blood cell in a hypotonic solution, causing water to move into the cell A red blood cell in a hypertonic solution, causing water to move out of the cell. Hemolysis or haemolysis (/ h iː ˈ m ɒ l ɪ s ɪ s /), [1] also known by several other names, is the rupturing of red blood cells (erythrocytes) and the release of their contents into surrounding fluid (e.g. blood plasma).
When alpha-hemolysis (α-hemolysis) is present, the agar under the colony will appear dark and greenish due to the conversion of hemoglobin to green biliverdin. Streptococcus pneumoniae and a group of oral streptococci ( Streptococcus viridans or viridans streptococci) display alpha-hemolysis.
In alpha-hemolysis, the blood is partially digested, causing the area around the colony to turn green. In beta-hemolysis, the organism digests the blood completely, leaving a clear area around each colony. [1]: 165–6 Organisms that do not produce hemolysis are referred to as gamma-hemolytic.
Alpha-hemolysin from uropathogenic E. coli produces extra-intestinal infections and can cause cystitis, pyelonephritis, and sepsis. Alpha-hemolysin from Staphylococcus aureus can cause severe diseases, such as pneumonia. Aerolysin from Aeromonas sobria infects the intestinal tract, but it might also cause sepsis and meningitis.
Alpha-toxin, also known as alpha-hemolysin (Hla), is the major cytotoxic agent released by bacterium Staphylococcus aureus and the first identified member of the pore forming beta-barrel toxin family. [1] This toxin consists mostly of beta sheets (68%) with only about 10% alpha helices.
Streptococcus mitis is a species of Gram-positive, mesophilic, alpha-hemolytic bacteria in the genus Streptococcus.These bacteria are facultative anaerobes, and made up of non-motile and non-sporing cocci (round cells) that are catalase negative.
Most strains are gamma-hemolytic (non-hemolytic), but some also display alpha-hemolytic activity on sheep blood agar plates. Strep bovis is a non-enterococci. [citation needed] Biochemical Tests mannitol salt: negative bile esculin: negative MR/VP: positive/negative nutrient gelatin: negative starch: positive DNase: negative [citation needed]