What is a common characteristic of the colonies formed by Proteus species on agar?

What is a common characteristic of the colonies formed by Proteus species on agar?

• A. They are pigmented with red color
• B. They exhibit swarming motility
• C. They form small, single colonies
• D. They remain static on the agar

Answer: (B)

Proteus species are highly motile and exhibit swarming motility on agar. Their surface movement is driven by many flagella and a tendency to differentiate into swarm cells, leading to coordinated, rapid spreading across the plate. This produces large, expanding colonies or a wave-like pattern that can cover the entire surface, sometimes with concentric rings. Because of this spreading behavior, Proteus colonies do not stay as small, discrete spots or remain static; they instead sweep across the agar, which is the hallmark seen in cultures. Pigmentation is not a defining feature on standard media, and the key characteristic you’ll notice is the swarming growth.

Proteus species are highly motile and exhibit swarming motility on agar. Their surface movement is driven by many flagella and a tendency to differentiate into swarm cells, leading to coordinated, rapid spreading across the plate. This produces large, expanding colonies or a wave-like pattern that can cover the entire surface, sometimes with concentric rings. Because of this spreading behavior, Proteus colonies do not stay as small, discrete spots or remain static; they instead sweep across the agar, which is the hallmark seen in cultures. Pigmentation is not a defining feature on standard media, and the key characteristic you’ll notice is the swarming growth.