Which pigment is produced by the Pseudomonas fluorescens group?

• A. Pyomelanin
• B. Pyocyanin
• C. Pyoverdin
• D. Pyorubrin

Answer: (C)

Pseudomonas fluorescens group is known for producing pyoverdin, a fluorescent pigment that also acts as a siderophore to bind iron in environments with limited iron. In culture, pyoverdin appears yellow-green and will fluoresce under ultraviolet light, which helps distinguish this group from others. Other pigments are associated with different Pseudomonas species: pyocyanin is the blue-green pigment typical of Pseudomonas aeruginosa, while pyomelanin is a brown-black pigment produced by some strains, and pyorubrin is not a hallmark pigment of this group. Because pyoverdin is the defining, fluorescing pigment linked to the Pseudomonas fluorescens group, it is the best answer.