Which organisms grow best in the temperature range of 0-15 °C?

• A. Psychrophiles
• B. Psychrotrophs
• C. Mesophiles
• D. Thermophiles

Answer: (A)

Organisms that grow best at cold temperatures are psychrophiles. They are adapted to function optimally in environments from about 0°C up to around 15°C, with enzymes and cellular membranes tuned for cold conditions. These adaptations include enzymes that remain active at low temperatures and membranes with more unsaturated fatty acids to stay fluid when it’s cold. That makes psychrophiles thrive in places like Arctic and Antarctic waters, snow, and permafrost.

In contrast, psychrotrophs can grow at 0°C but prefer warmer conditions, with their optimum around room to body temperatures. Mesophiles favor moderate temperatures, roughly 20–45°C, while thermophiles need hot environments, often above 45°C. Therefore, the temperature range 0–15°C aligns best with psychrophiles, explaining why they’re the correct answer.