Which of the following pairs of microbe classification terms and optimal growth temperatures is mismatched?
A psychrophile growth at 37°C
B psychrotroph growth at 22°C
C mesophile growth at 37°C
D hyperthermophiles growth at 95°C
The correct answer and explanation is :
Correct Answer: A. Psychrophile growth at 37°C
Explanation:
Microorganisms are classified based on their optimal growth temperatures into distinct categories such as psychrophiles, psychrotrophs, mesophiles, thermophiles, and hyperthermophiles. Each category describes organisms adapted to thrive at specific temperature ranges.
A. Psychrophile – growth at 37°C (Mismatched)
This is the correct answer because it is mismatched. Psychrophiles are cold-loving microbes that grow best at very low temperatures, typically between -5°C and 15°C, and are rarely found thriving above 20°C. They are commonly found in deep ocean waters, polar regions, and glaciers. Growth at 37°C, which is human body temperature, would inhibit or even kill true psychrophiles. Therefore, pairing a psychrophile with 37°C is incorrect.
B. Psychrotroph – growth at 22°C (Matched)
Psychrotrophs prefer cooler environments but can tolerate and grow at a wider temperature range than psychrophiles. Their optimal growth temperature is usually 20–30°C, but they can grow slowly at temperatures as low as 0°C. These organisms are often responsible for food spoilage in refrigerated environments. Thus, 22°C is within their optimal range.
C. Mesophile – growth at 37°C (Matched)
Mesophiles thrive at moderate temperatures, typically between 20°C and 45°C, with optimal growth around 37°C, which is also the temperature of the human body. Most human pathogens and normal flora are mesophiles. Therefore, this match is accurate.
D. Hyperthermophile – growth at 95°C (Matched)
Hyperthermophiles grow optimally at extremely high temperatures, usually above 80°C. Some can survive and thrive at temperatures close to 100°C, such as those found in hydrothermal vents. Therefore, 95°C is a suitable growth temperature for this group.
Summary:
The only mismatched pair is A (psychrophile – 37°C) because psychrophiles are adapted to cold environments and cannot survive at high temperatures like 37°C.