Which organism is known for violet pigment production on colonies?

Which organism is known for violet pigment production on colonies?

• A. Chromobacterium violaceum
• B. Chryseobacterium meningosepticum
• C. Pseudomonas aeruginosa
• D. Serratia marcescens

Answer: (A)

Violet pigment production on colonies is a distinctive visual trait used to identify certain bacteria. Chromobacterium violaceum naturally makes a violet pigment called violacein, so its colonies appear purple on standard agar. This color cue helps distinguish it from other common organisms, whose pigments tend to be different—Pseudomonas aeruginosa often shows blue-green pigment due to pyocyanin, Serratia marcescens can produce a red pigment (prodigiosin) at room temperature, and Chryseobacterium meningosepticum may have yellow-orange pigments. The violet hue is a hallmark feature of Chromobacterium violaceum.

Violet pigment production on colonies is a distinctive visual trait used to identify certain bacteria. Chromobacterium violaceum naturally makes a violet pigment called violacein, so its colonies appear purple on standard agar. This color cue helps distinguish it from other common organisms, whose pigments tend to be different—Pseudomonas aeruginosa often shows blue-green pigment due to pyocyanin, Serratia marcescens can produce a red pigment (prodigiosin) at room temperature, and Chryseobacterium meningosepticum may have yellow-orange pigments. The violet hue is a hallmark feature of Chromobacterium violaceum.