What does the term poikilothermic refer to in microbes?

The term poikilothermic, when applied to microbes, refers to organisms that cannot internally regulate their body temperature and instead exhibit body temperatures that fluctuate with the surrounding environmental temperature. This characteristic is typical of many microorganisms, which means they rely on external sources of heat to maintain their metabolic processes.

In contrast, constant body temperature regardless of the environment describes homeothermic organisms, which is not applicable to poikilothermic microbes. The ability to maintain temperature in extreme environments and resistance to temperature changes imply a certain level of thermoregulation that poikilothermic microbes do not possess. Thus, the definition of poikilothermic aligns precisely with the notion of fluctuating body temperatures in response to environmental changes, making it the correct description.