Question

The optimum temperature for rapid growth of mesophiles is:

• A. 40 to 50 °C
• B. 50 to 60 °C
• C. 15 to 20 °C
• D. 25 to 40 °C

Answer 1

The Correct Option is D

The correct option is (D): 25 to 40 °C.

Answer 2

The question asks for the optimum temperature range for rapid growth of mesophiles, a broad group that includes most human pathogens and common environmental bacteria. Let's check each range.

1. 40 to 50 °C: This range is closer to the growth range of thermophiles, organisms adapted to warmer or hot environments, and is higher than what mesophiles need for their fastest growth.
2. 50 to 60 °C: This range is well within the thermophilic range and would be too hot for most mesophilic organisms to grow efficiently, let alone at their optimum rate.
3. 15 to 20 °C: This range is more typical of psychrophiles or cold-tolerant organisms. It is too cool for mesophiles to reach their fastest growth rate, even though many mesophiles can survive at the lower end of this range.
4. 25 to 40 °C: Mesophiles are defined as organisms that grow best at moderate temperatures, and this range, which includes normal room temperature and human body temperature around 37 °C, is exactly where most mesophiles including many pathogenic bacteria show their fastest growth.

Mesophiles are named for their preference for moderate temperatures, and 25 to 40 °C is the range where they multiply most rapidly.

Therefore, the correct answer is 25 to 40 °C.