What characteristic differentiates psychrophiles from psychrotolerant organisms?

Psychrophiles are specialized microorganisms that thrive in cold environments, with an optimal growth temperature typically between -5°C to 15°C, and can actively grow at temperatures as low as 0°C. This ability to grow at such low temperatures is a key characteristic that distinguishes psychrophiles from psychrotolerant organisms.

Psychrotolerant organisms, on the other hand, are those that can grow at elevated temperatures but still have the capacity to grow at lower, cold temperatures, such as around 0°C. However, their growth is not limited to cold environments; they have a broader optimal temperature range that usually includes temperatures above 15°C. This distinction highlights that while both types of organisms can survive in cold conditions, true psychrophiles are adapted for and prefer those colder temperatures, allowing them to be more efficient at lower temperatures compared to psychrotolerant organisms.