What grows on MacConkey agar plates?
MacConkey agar (MAC) is a bacterial culture medium named after bacteriologist Alfred T. MacConkey (1861-1931). MacConkey agar is a selective and differentiating agar that only grows gram-negative bacterial species; it can further differentiate the gram-negative organisms based on their lactose metabolism.
What Agar does E coli grow on?
coli is able to grow on a wide range of carbon sources, but is typically grown in a rich medium, such as Luria-Bertani broth, or on rich medium agar plates (see Reagents and Solutions for recipes or see Current Protocols article Stevenson, 2006, for protocols describing the preparation of commonly used liquid and solid …
What type of bacteria does MacConkey support the growth of?
MacConkey agar is a selective and differential culture media commonly used for the isolation of enteric Gram-negative bacteria. It is selective as it allows the growth of gram-negative bacteria and differential as it differentiates the gram-negative bacteria based on their lactose metabolism.
Can E coli grow on blood agar?
E coli is a gram-negative bacillus that grows well on commonly used media. It is lactose-fermenting and beta-hemolytic on blood agar.
What is the difference between blood agar and chocolate agar?
Chocolate agar is prepared by heating blood agar, which in turn ruptures the red blood cell (RBC) and releases nutrients that aid in the growth of fastidious bacteria, most notably Haemophilus and Neisseria species. The name is derived from the fact that the lysis of RBC gives the medium a chocolate-brown color.
What type of medium is chocolate agar?
Chocolate agar (CHOC) or chocolate blood agar (CBA), is a nonselective, enriched growth medium used for isolation of pathogenic bacteria. It is a variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating to 80°C.
Is blood agar selective?
Blood Agar Is Not a Selective Medium Blood agar is an enriched medium that provides an extra rich nutrient environment for microbes. Therefore, BAP is not a selective growth medium, since it supports the growth of a wide range of organisms.
What does a blood agar test for?
Blood Agar Plates (BAP) BAP tests the ability of an organism to produce hemolysins, enzymes that damage/lyse red blood cells (erythrocytes). The degree of hemolysis by these hemolysins is helpful in differentiating members of the genera Staphylococcus, Streptococcus and Enterococcus.
What types of bacteria grow on blood agar?
Blood Agar is used to grow a wide range of pathogens particularly those that are more difficult to grow such as Haemophilus influenzae, Streptococcus pneumoniae and Neisseria species. It is also required to detect and differentiate haemolytic bacteria, especially Streptococcus species.
Why is blood agar useful as a primary isolation medium?
Blood agar is useful as a primary isolation medium because it supports the growth of about any bacteria. It is nonselective and is used for primary isolation purposes for aerobic and anaerobic cultures in lab.
Why do you stab a blood agar plate?
The hemolysins produced by streptococci perform better in an anaerobic environment. Because of this, it is standard procedure to streak a blood plate and then stab the loop into the agar to provide an area of lower oxygen concentration where the streptolysins can more effectively break down the blood cells.
Why is human blood not used in blood agar?
Agar prepared with human blood is not recommended, partly because of the safety risk to laboratory personnel, but mainly because it is said to result in poor bacterial isolation rates, although there are few published data to support this (2).
What does Alpha hemolysis look like on blood agar?
Alpha hemolysis (α) is the reduction of the red blood cell hemoglobin to methemoglobin in the medium surrounding the colony. This causes a green or brown discoloration in the medium. The color can be equated with “bruising” the cells.
How will this hemolysis show up on a blood agar plate?
After incubating an inoculated blood agar plate, observe the media around the bacteria growing on it. Look for changes in the opaque, red color. If the area around the bacteria turns transparent, that strain displays complete hemolysis, also known as beta hemolysis. Such a strain would be called beta-hemolytic.
What does hemolysis on blood agar mean?
Hemolysis (from Greek αιμόλυση, meaning ‘blood breakdown’) is the breakdown of red blood cells. The ability of bacterial colonies to induce hemolysis when grown on blood agar is used to classify certain microorganisms. A substance that causes hemolysis is a hemolysin.
What are the three types of hemolysis?
There are three types of hemolysis, designated alpha, beta and gamma.