Question

Match List-I with List-II

List-I (Colony characters)	List-II (Name of specific bacteria)
(A) Swarming growth on Nutrient agar	(I) Hemophillus
(B) Metallic sheen on Eosin Methylene Blue agar	(II) Pseudomonas
(C) Green pigment on Nutrient agar	(III) Proteus
(D) Growth on Chocolate agar	(IV) Escherichia coli

• (A) - (III), (B) - (IV), (C) - (II), (D) - (I)
• (A) - (II), (B) - (IV), (C) - (I), (D) - (III)
• (A) - (I), (B) - (II), (C) - (IV), (D) - (III)
• (A) - (III), (B) - (IV), (C) - (I), (D) - (II)

Hint:

Associate these unique bacterial characteristics:
- *Proteus* \(\rightarrow\) Swarming (always moves like a wave).
- *E. coli* on EMB \(\rightarrow\) Metallic green sheen (very classic board question).
- *Pseudomonas* \(\rightarrow\) Green pigment (produces pyocyanin).
- *Haemophilus* \(\rightarrow\) Chocolate agar (fastidious, requires lysed RBC factors).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Bacterial species exhibit characteristic growth patterns, pigments, and nutritional requirements when cultivated on specific agar media.
These phenotypic features are highly useful for the presumptive identification of bacteria in veterinary diagnostic laboratories.

Step 2: Detailed Explanation:
Let us analyze each of the colony characteristics in List-I and match them with the bacterial genera in List-II:
- (A) Swarming growth on Nutrient agar: This is a classic characteristic of *Proteus* species (such as *Proteus vulgaris* or *Proteus mirabilis*).
Due to their hyperflagellated, highly motile state (called "swarmer cells"), they migrate outward from the initial site of inoculation on moist agar surfaces.
This results in concentric, wave-like rings of growth rather than isolated colonies.
Thus, (A) matches with (III).
- (B) Metallic sheen on Eosin Methylene Blue (EMB) agar: This is a classic diagnostic feature of *Escherichia coli*.
*E. coli* is a vigorous lactose fermenter.
It produces large amounts of acid on EMB agar, which precipitates the eosin and methylene blue dyes, forming a distinctive dark colony with a metallic green sheen.
Thus, (B) matches with (IV).
- (C) Green pigment on Nutrient agar: This is characteristic of *Pseudomonas* species, especially *Pseudomonas aeruginosa*.
It produces water-soluble, diffusing pigments, including pyocyanin (blue-green) and pyoverdine (fluorescent yellow-green), which diffuse into the surrounding nutrient agar, giving it a green color.
Thus, (C) matches with (II).
- (D) Growth on Chocolate agar: Chocolate agar is a non-selective, enriched growth medium containing lysed red blood cells.
It is used for growing fastidious respiratory bacteria, such as *Haemophilus* species (e.g., *Haemophilus influenzae* or *Haemophilus parasuis*), which require growth factors present inside red blood cells, namely factor V (nicotinamide adenine dinucleotide, NAD) and factor X (hemin).
Thus, (D) matches with (I).
Therefore, the correct matching is: (A) - (III), (B) - (IV), (C) - (II), (D) - (I).

Step 3: Final Answer:
The correct option is (A).