Why do Streptococcus pneumoniae colonies on SBA sometimes appear like a coin-raised edges and a depressed center?
A) The older growth at the center is smaller due to lack of nutrients.
B) The newer growths on the outside of the colony undergo the Quellung reaction.
C) The older growth at the center is killed due to autolysis.
D) The newer growth has a thicker capsule, therefore it appears raised.

Question

Quizplus · Accepted Answer

Streptococcus pneumoniae colonies on SBA can undergo autolysis, which is a process where the older cells in the central portion of the colony release enzymes that break down the cell wall, causing a depressed center. The newer growth on the outside of the colony may continue to grow and form a raised edge.

Why Do Streptococcus Pneumoniae Colonies on SBA Sometimes Appear Like