Biology

Difference between alpha hemolysis and beta hemolysis

Main difference

The main difference between alpha hemolysis and beta hemolysis is that alpha hemolysis is associated with partial hemolysis and is related to reduced hemoglobin levels in red blood cells, while beta hemolysis is associated with complete hemolysis of the red blood cells that generally occur around the colony.

Alpha hemolysis vs. beta hemolysis

Alpha hemolysis usually indicates partial hemolysis of red blood cells and greenish staining, some streptococci present on blood agar plates immediately surround the colonies; on the other hand, beta hemolysis indicates complete degradation of red blood cells illustrated by the perfect zone that generally surrounds the colony of bacteria present on blood agar plates.

Partial hemolysis or green hemolysis are some other names for alpha hemolysis; conversely, complete hemolysis is also known as beta hemolysis. Alpha hemolysis is known as the type of partial hemolysis of red blood cells; On the other hand, beta hemolysis is known as the complete red blood cell type of hemolysis.

Alpha hemolysis is usually caused by hydrogen peroxide, which is formed by bacteria, while beta hemolysis is normally caused by by-products of toxic substances that always destroy red blood cells. In the process of alpha hemolysis, hydrogen peroxide dissolves hemoglobin (red) in methemoglobin (green), while beta hemolysis, beta hemolysis, completely breaks down all red blood cells.

In alpha hemolysis, the red blood cells remain intact; on the other hand, in beta hemolysis, red blood cells break down. Alpha hemolysis forms greenish-black regions; on the other hand, beta hemolysis forms clear and perfect areas.

The width of the zone in alpha hemolysis is 1-2 mm; conversely, the width of the beta-hemolyzed area is 2-4 mm. Some types of streptococci from alpha hemolysis are Streptococcus pneumonia and Streptococcus viridian, while only Streptococcus pyogenes goes on to beta hemolysis. Species that undergo alpha hemolysis are found in the oral cavity, while species that undergo beta hemolysis are found in the throat.

Comparative chart
Alpha hemolysis Beta hemolysis
Alpha hemolysis is known as the process in which the incomplete destruction of red blood cells takes place. Beta hemolysis is known as the process in which the destruction of red blood cells takes place.
Alternative names
Partial hemolysis or green hemolysis Complete hemolysis
Hemolysis type
The type that is partial hemolysis of red blood cells. The kind that is complete red blood cell hemolysis.
Enzyme involved
Catalyzed by the enzyme alpha-hemolysin Catalyzed by the enzyme beta-hemolysin
Hemolysins
Caused by the hydrogen peroxide formed by the bacteria. Caused by the by-products of toxic substances that always destroy red blood cells.
Process
Hydrogen peroxide dissolves hemoglobin (red) in methemoglobin (green) Beta hemolysis completely breaks down all red blood cells
Rupture of red blood cells
Red blood cells remain intact Red blood cells break down
Change
Forms greenish-black regions Forms clear and perfect areas
Zone Width
The size of the zone is 1-2 mm. The size of the zone is 2-4 mm.
Types of streptococci
Streptococcus pneumonia and Streptococcus viridians Streptococcus pyogenes
Location
Species that undergo alpha hemolysis are found in the oral cavity. Species that undergo beta hemolysis are found in the throat.

What is alpha hemolysis?

Alpha hemolysis is known as partial hemolysis of the red blood cells that form the greenish discoloration, which is present around the bacterial colony on blood agar plates. Alpha hemolysis is also known as partial hemolysis or green hemolysis.

Alpha hemolysis is caused by various Streptococcus species such as Streptococcus pneumonia, Streptococcus mitis, Streptococcus mutans, Streptococcus salivarius, and Streptococcus viridians. Alpha hemolysis is considered as the type of partial hemolysis in which the iron molecules present in hemoglobin are dissolved by hydrogen peroxide, which is produced by the bacteria.

Partial hemolysis gives a greenish color to the environment of the colony of bacteria because hemoglobin (red) is converted to methemoglobin (green). Alpha hemolysis is the incomplete breakdown of red blood cells, and these red blood cells remain intact during contagion in the body.

The process of alpha hemolysis is usually catalyzed by the bacterial hemolytic enzyme known as alpha-hemolysin. Prolonged incubation in alpha hemolysis allows the formation of clear areas. Alpha hemolysis is used as an indicative feature during bacterial strain credentials. Species that undergo alpha hemolysis are found in the oral cavity.

What is beta hemolysis?

Beta hemolysis is known as the complete breakdown and destruction of red blood cells. Beta hemolysis is also known as complete hemolysis. Beta hemolysis forms a clear area around the bacterial colony on the blood agar plate.

Beta hemolysis always participates in true or complete red blood cell hemolysis. The complete breakdown of red blood cells is due to the by-products of toxic substances.

Streptolysin O hemolysin is produced by Streptococcus pyogenes and is only active under low oxygen conditions. In the agar plate, anaerobic compartments are produced by piercing an injection ring vertically in the agar, after flashing the plate.

The oxygen-stable Streptolysin S hemolysin is produced by some Streptococcus pyogenes. Some beta hemolysis reactions are considered very delicate and some of these weak hemolysis reactions occur in Streptococcus agalactiae or Listeria monocytogenes.

Bacterial hemolytic enzymes destroyed the cell membranes of red blood cells. Hence, hemoglobin molecules are released into the body’s blood plasma. The bacterial enzyme known as beta-hemolysin is the cause of the occurrence of beta hemolysis and those bacteria are known as beta-hemolytic bacteria.

Species that undergo beta hemolysis are found in the throat. As beta hemolysis completely breaks down red blood cells, light areas begin to be visible around the bacterial colonies.

Key differences

  1. The incomplete destruction of red blood cells is known as alpha hemolysis; On the other hand, the destruction of red blood cells in the blood is known as beta hemolysis.
  2. The enzyme involved in the degradation of cells in alpha hemolysis is alpha-hemolysin; on the contrary, the enzyme that participates in the degradation of cells in beta hemolysis is beta-hemolysin.
  3. The alpha hemolysis bacteria are Streptococcus mitis, pneumonia, mutans, and S. salivarius; on the other hand, the bacteria in beta hemolysis are pyogenes and S. agalactiae.
  4. Hydrogen peroxide caused alpha hemolysis, which is formed by bacteria; on the contrary, the by-products of toxic substances that destroy red blood cells caused beta hemolysis.
  5. Blood cells remain in contact in alpha hemolysis, while cells break down completely in beta hemolysis.
  6. Greenish-black regions are usually formed by alpha hemolysis, while beta hemolysis forms clear, perfect regions.
  7. Hydrogen peroxide catalyzes hemoglobin to methemoglobin in the alpha hemolysis mechanism; conversely, all red blood cells are completely disrupted in the beta hemolysis process.

Final Thought

The above discussion concludes that both types of alpha and beta hemolysis occur from infection of the different Streptococcus species, and both have differences. Alpha hemolysis is a form of partial hemolysis and forms green areas, while beta hemolysis is a type of complete hemolysis and forms clear areas.

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