Question

A researcher's agar plate becomes partially contaminated with an unknown contaminant. When growing a culture of gram-negative bacteria on the plate, only the area with the contaminant is clear the next morning. The contaminant is most likely:

A. a phage in the lytic phase
B. a nutrient broth lacking an essential nutrient for the bacteria
C. a phage in the lysogenic phase
D. distilled water

Answer 1

The likely contaminant causing clear areas on an agar plate culture of gram-negative bacteria is a phage in the lytic phase.

Step-by-step explanation:

The contaminant on the researcher's agar plate that caused a clear area the next morning in the culture of gram-negative bacteria is most likely a phage in the lytic phase.

This is indicated by the clear area where the contaminant is present, likely due to the lytic cycle of bacteriophages where they infect and subsequently lyse the bacteria, forming clear plaques.

Other options such as a nutrient broth lacking an essential nutrient, a phage in the lysogenic phase, or distilled water would not result in clear areas due to bacterial lysis.