An organism grown in nutrient rich broth to high turbidity always produces a blue pigment. When a large inoculum is transferred to a nutrient rich agar plate, it also appears blue. A researcher noticed that this never happens when very small colonies are grown on low nutrient agar plates, however. What is the most plausible conclusion?
A) Large populations enabled the differentiation of a subpopulation of cells that created the blue pigment.
B) Only high nutrient conditions provide enough energy for cells to produce this secondary metabolite that appears blue.
C) Production of the blue pigment production is linked to quorum sensing.
D) The strong gradient from very high to low nutrient bioavailability induces production of the blue metabolite.

Question

Quizplus · Accepted Answer

The fact that the blue pigment is produced in high nutrient broth and on nutrient-rich agar plates, but not in small colonies on low nutrient agar plates, suggests that the production of the pigment is linked to quorum sensing. Quorum sensing allows bacterial populations to coordinate gene expression and behavior in response to their population density, which would explain why the pigment is only produced in high-density environments.

An Organism Grown in Nutrient Rich Broth to High Turbidity