Multiple Choice Question

Question

The table shows the pH ranges that support the growth of different bacteria.

Bacteria pH range
Salmonella 3.6–9.5
Listeria monocytogenes 4.2–9.6
Escherichia coli 4.3–9.0

What happens to these organisms at a pH of 3.7?
A.
Salmonella, Listeria monocytogenes and Escherichia coli do not grow.

B.
Listeria monocytogenes grows. Salmonella and Escherichia coli do not grow.

C.
Salmonella grows. Listeria monocytogenes and Escherichia coli do not grow.

D.
Escherichia coli grows. Listeria monocytogenes and Salmonella do not grow.

Answer 1

To determine the growth of the bacteria at a pH of 3.7, we can refer to their specified pH ranges:

• Salmonella: 3.6–9.5 (can grow at pH 3.7)
• Listeria monocytogenes: 4.2–9.6 (cannot grow at pH 3.7)
• Escherichia coli: 4.3–9.0 (cannot grow at pH 3.7)

Based on this information, at a pH of 3.7:

• Salmonella can grow, while
• Listeria monocytogenes and Escherichia coli cannot grow.

Thus, the correct answer is:

C. Salmonella grows. Listeria monocytogenes and Escherichia coli do not grow.