Question: How Do You Make Blood Agar?

What is the purpose of agar?

Nutrient Agar is a general purpose, nutrient medium used for the cultivation of microbes supporting growth of a wide range of non-fastidious organisms.

Nutrient agar is popular because it can grow a variety of types of bacteria and fungi, and contains many nutrients needed for the bacterial growth..

What is the indicator in blood agar?

Phenol red is the pH indicator. Motility-Indole-Ornithine Agar: motility is indicated by the character of the growth in the butt of this tube.

What grows MacConkey Agar?

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.

How do you interpret MacConkey Agar?

Result Interpretation on MacConkey Agar Lactose fermenting strains grow as red or pink and may be surrounded by a zone of acid precipitated bile. The red colour is due to production of acid from lactose, absorption of neutral red and a subsequent colour change of the dye when the pH of medium falls below 6.8.

What Colour is MacConkey Agar?

pinkMacConkey agar with LF and non-LF colonies. The organism on the left is a lactose fermenter, as evidenced by the pink color.

Why do we use blood agar?

Many species of bacteria produce toxic by-products that are capable of destroying red blood cells. Blood agar is a general purpose enriched medium often used to grow fastidious organisms and to differentiate bacteria based on their hemolytic properties.

What color is E coli on MacConkey Agar?

dark pinkPresumptive identification of E. coli was made based on its characteristic morphology colony on the selective medium MacConkey agar. Rapid lactose fermenting colonies of E. coli appear dry, donut shaped and dark pink in color and are surrounded with dark pink area of precipitated bile salts.

Why is blood agar differential?

Blood agar is differential media because 3 different types of hemolysis, or lysing of red blood cells, can be seen on this plate. … Beta hemolytic organisms completely lyse red blood cells, leaving an area of total clearing underneath and around the colonies.

What is the difference between EMB agar and MacConkey Agar?

An example of a selective medium is MacConkey agar. It contains bile salts and crystal violet, which interfere with the growth of many gram-positive bacteria and favor the growth of gram-negative bacteria. … EMB contains the dyes eosin and methylene blue that inhibit the growth of gram-positve bacteria.

What is the difference between blood agar and chocolate agar?

The composition of chocolate agar and the Blood Agar is the same and the only difference is while preparing chocolate agar, the red blood cells are lysed. … Neither of these species is able to grow on sheep blood agar. Chocolate agar slants are used for the short-term storage of pathogens such as N.

Does Salmonella grow on blood agar?

Blood agar – Colonies are moist and 2-3mm in diameter. CLED agar – Salmonella species are lactose non fermenters (some serotypes e.g. Salmonella Arizonae and Salmonella Indiana may ferment lactose).

What is blood agar made of?

Blood agar consists of a base containing a protein source (e.g. Tryptones), soybean protein digest, sodium chloride (NaCl), agar, and 5% sheep blood.

Why is human blood not used in blood agar?

However, the use of easily available human blood for blood agar is discouraged because of the common tenet that human blood in nutrient media results in poor bacterial isolation rates and hardly visible hemolysis or no hemolysis at all.

Is blood agar selective?

Blood Agar Is Not a Selective Medium If a bacterial growth medium is selective, that means that it grows only certain types of microbes while inhibiting the growth of other types of microbes. Blood agar is an enriched medium that provides an extra rich nutrient environment for microbes.