Question

The common milk microorganisms grow best between the temperature -

• A. 5°C to 10°C
• B. 20°C to 40°C
• C. 3°C to 4°C
• D. -5°C to 0°C

Hint:

When a question asks about "common" or "typical" bacteria without further qualification, it's usually referring to mesophiles. Think of room temperature or body temperature as their "sweet spot" for growth.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The question asks for the optimal temperature range for the growth of "common milk microorganisms". This generally refers to the largest and most diverse group of bacteria found in milk, which are the mesophiles.
Step 2: Detailed Explanation:
Bacteria are classified by their optimal growth temperatures. Let's analyze the given ranges:
(A) 5°C to 10°C and (C) 3°C to 4°C: This is the range for psychrotrophic bacteria, which are important for spoilage of refrigerated milk but are not the most "common" or numerous group overall.
(B) 20°C to 40°C: This is the classic temperature range for mesophilic bacteria. This group includes a vast number of species, including many starter cultures (Lactococcus), spoilage organisms, and pathogens (E. coli, Staphylococcus aureus). They thrive at room and body temperatures, making this the ideal range for the most common milk microorganisms.
(D) -5°C to 0°C: This is below the freezing point of water. While some microbes can survive, active growth is generally halted.
Step 3: Final Answer:
The temperature range of 20°C to 40°C is optimal for the growth of mesophilic bacteria, which represent the most common microorganisms associated with milk.