Certified Cheese Professional Practice Exam

Which of the following best describes a thermophilic bacterium?

1. It thrives in low temperatures

2. It thrives in moderate temperatures

3. It thrives in high temperatures

4. It cannot tolerate heat

The correct answer is: It thrives in high temperatures

A thermophilic bacterium is defined by its ability to thrive at high temperatures, typically between 45°C and 75°C (113°F to 167°F). These bacteria are specially adapted to such extreme thermal environments and have proteins and cellular structures that maintain stability and function at elevated temperatures. This adaptation allows them to play significant roles in processes like fermentation and the decomposition of organic materials in hot environments, making them crucial for various industrial applications, including cheese production. In contrast, the other options reflect characteristics of different types of bacteria. Bacteria that thrive in low temperatures are referred to as psychrophilic, while those that prefer moderate temperatures are known as mesophilic. Bacteria that cannot tolerate heat at all would include many pathogenic microorganisms which are sensitive to temperature increases and do not grow well in thermal conditions. Thus, the description of thermophilic bacteria aligns specifically with their success in high-temperature environments.