Question

The optimum temperature for rapid growth of mesophiles is:

• A. \( 40^\circ C \text{ to } 50^\circ C \)
• B. \( 50^\circ C \text{ to } 60^\circ C \)
• C. \( 15^\circ C \text{ to } 20^\circ C \)
• D. \( 25^\circ C \text{ to } 40^\circ C \)

Hint:

Microorganisms are classified by their optimum growth temperatures: 
- Psychrophiles: \( -5^\circ C \) to \( 15^\circ C \). 
- Mesophiles: \( 20^\circ C \) to \( 45^\circ C \). 
- Thermophiles: \( 45^\circ C \) to \( 80^\circ C \). 
Understanding these classifications helps in microbiology and industrial processes.

Answer 1

The Correct Option is D

Step 1: Understanding mesophiles. Mesophiles are microorganisms that thrive in moderate temperature ranges. They are commonly found in environments such as soil, water, and the human body. 

Step 2: Optimum temperature range. Mesophiles grow best at temperatures between \( 20^\circ C \) and \( 45^\circ C \), with the most rapid growth occurring between \( 25^\circ C \) and \( 40^\circ C \). 
This range supports their metabolic and enzymatic activities. 

Conclusion: The correct answer is \( (D) \ 25^\circ C \text{ to } 40^\circ C \).

Answer 2

The question asks for the temperature range in which mesophiles, a broad group of microorganisms that includes most human pathogens and common environmental bacteria, grow fastest. Let's check each range against what mesophiles actually need.

1. \( 40^{\circ}C \) to \( 50^{\circ}C \): This range starts to overlap with the lower end of thermophile growth, organisms adapted to heat, and is warmer than what typical mesophiles can tolerate for rapid growth.
2. \( 50^{\circ}C \) to \( 60^{\circ}C \): This range is firmly in thermophile territory, well above what mesophilic enzymes and membranes can function normally in.
3. \( 15^{\circ}C \) to \( 20^{\circ}C \): This range is closer to what psychrophiles, cold-loving organisms, prefer, and is too cool for mesophiles to reach their fastest growth rate.
4. \( 25^{\circ}C \) to \( 40^{\circ}C \): This moderate range matches typical environments like soil, water, and the human body, roughly \( 37^{\circ}C \), where mesophilic enzymes work most efficiently and cell division happens fastest.

Mesophiles are defined by their preference for moderate warmth, and their fastest growth happens in the 25 to 40 degree Celsius band, which includes normal body temperature, unlike the cooler or hotter ranges in the other options.

So the correct answer is \( 25^{\circ}C \) to \( 40^{\circ}C \).