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.
C. Salmonella grows. Listeria monocytogenes and Escherichia coli do not grow.
The correct answer is D.
At a pH of 3.7, Escherichia coli grows, while Listeria monocytogenes and Salmonella do not grow.
Based on the pH ranges shown in the table, we can determine the impact of a pH of 3.7 on the growth of Salmonella, Listeria monocytogenes, and Escherichia coli. To do this, we compare the pH range of each bacteria with the given pH value individually.
Salmonella has a pH range of 3.6-9.5. Since 3.7 falls within this range, Salmonella is capable of growing at a pH of 3.7.
Listeria monocytogenes has a pH range of 4.2-9.6. Similarly, 3.7 falls within this range, indicating that Listeria monocytogenes can grow at a pH of 3.7 as well.
Escherichia coli has a pH range of 4.3-9.0. However, 3.7 is outside of this range, which means that Escherichia coli cannot grow at a pH of 3.7.
Therefore, the correct answer is:
D. Escherichia coli grows. Listeria monocytogenes and Salmonella do not grow.