In: Biology
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 Organism  | 
 (MacConkey) MAC  | 
 Nutrient Agar  | 
 Horse Blood Agar  | 
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 E. coli  | 
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 Klebsiella pneumoniae  | 
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 Proteus mirabilis  | 
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 Pseudomonas aeruginosa.  | 
 
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Answer:-
A) E.coli colonies:
MacConkey- donut shaped and dark pink in color and are surrounded with dark pink area of precipitated bile salts.
Horse blood Agar- Colonies are big, circular, gray and moist. There is clearing of agar around a colony. It represents a complete breakdown of the hemoglobin of the RBC around the bacterial colony.
Nutrient Agar- They appear large, circular, low convex, grayish, white, moist, smooth and opaque.
B)Klebsiella pneumoniae:
MacConkey- colonies are large shiny and dark pink in color.
Nutrient Agar- colonies are circular, dome shaped & greyish-white.
Horse blood Agar- colonies are circular, dome shaped and greyish-white . No clearing of agar is present around the colonies , thus gamma hemolysis is present.
C) Proteus mirabilis:
MacConkey- They are non-lactose fermenting bacteria and have colorless or transparent colonies. Fishy odour present.
Horse blood Agar- Swarming effect on blood agar plate due to active motility of bacteria.
D) Pseudomonas aeruginosa:
MacConkey- It produces clear colonies on MacConkey agar as it is non-lactose fermenting bacteria.
Nutrient Agar- colonies produces greenish colour due to production of pyoverdin.
Horse blood Agar- Colonies are surroundend by a wide zone of beta-hemolysis.