Question

According to optimum growth temperature, bacteria associated with milk are not included in following group -

• A. Psychrotropic
• B. Mesophilic
• C. Thermophilic
• D. Endophilic

Hint:

The three key temperature groups in dairy are: {Psychro-} (cold-loving spoilage bacteria), {Meso-} (middle-temperature loving bacteria, including pathogens and many starters), and {Thermo-} (heat-loving bacteria for products like yogurt). Any other "-philic" term in a temperature context is likely a distractor.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The question asks to identify the term that is not a standard classification for bacteria based on their optimal growth temperature, particularly in the context of dairy microbiology.
Step 2: Detailed Explanation:
Microbiologists classify bacteria into several groups based on their preferred temperature ranges for growth:
Psychrotrophic (or Psychrotolerant): These bacteria can grow at refrigeration temperatures (0-7°C) but their optimum is higher. They are major spoilage organisms in refrigerated milk. Examples include Pseudomonas.
Mesophilic: These bacteria grow best at moderate temperatures, typically between 20°C and 45°C. This group includes most human pathogens and many dairy starter cultures (e.g., for Cheddar cheese).
Thermophilic: These bacteria prefer high temperatures, typically between 45°C and 70°C. They are used as starter cultures for high-temperature products like yogurt and Swiss cheese.
Endophilic: This is not a standard term used to classify bacteria based on their temperature requirements. The term "philic" means "loving," and "endo" means "within." The term has no established meaning in the context of bacterial temperature classification.
Step 3: Final Answer:
Psychrotrophic, Mesophilic, and Thermophilic are the three major temperature-based groups of bacteria relevant to the dairy industry. Endophilic is not a part of this classification.