Question

When s. marcescens, a bacterium, is grown in a refrigerator, it produces red-colored colonies. however, if the bacterium is grown at room temperature, the colonies are white. the best explanation for this situation is that?

Answer 1

Serratia marcescens bacteria produce red-colored colonies in a refrigerator, but white colonies at room temperature due to the temperature-dependent expression of a gene that produces a red pigment.

Step-by-step explanation:

The best explanation for why Serratia marcescens bacteria produce red-colored colonies when grown in a refrigerator, but white colonies when grown at room temperature, is due to the temperature-dependent expression of a gene that produces a red pigment. This gene is only expressed at lower temperatures. When the bacteria are grown in a refrigerator at cooler temperatures, the red pigment gene is activated, resulting in the production of red-colored colonies. However, at room temperature, the gene is not expressed, leading to the absence of the red pigment and the formation of white colonies.

Answer 2

Serratia marcescens primarily produces a bright red pigment called prodigiosin. Depending on the synthesis (partial or complete) of prodigiosin, the colour of the colony can be different. At the room temperature, prodigiosin production decrease which results in the white colour of Serratia. Serratia can also be colourless due to prolonged sunlight (UV mutagenesis).