Temperature classes of microbes Which of the following temperature ranges best represents mesophiles (microorganisms with moderate temperature preference)?

Introduction / Context:Microbial growth strongly depends on temperature. For process control, food safety, and clinical microbiology, it is important to recognize typical ranges for psychrophiles (cold-loving), mesophiles (moderate), and thermophiles (heat-loving). The question asks for the temperature range typical of mesophiles.

Given Data / Assumptions:

• Mesophiles inhabit environments such as the human body, soils, and freshwater.
• They generally show optimal growth around body/ambient temperatures.
• Provided ranges include moderate, cold, and high-temperature values.

Concept / Approach:Mesophiles usually grow between about 20°C and 45°C, with optima commonly near 30–37°C. A concise range that captures the heart of mesophilic growth and typical optima is 25–40°C. Values above 40–45°C start to favor thermophiles or thermotolerant organisms, while values below ~20°C suit psychrophiles or psychrotrophs.

Step-by-Step Solution:Recall standard ranges: psychrophiles (<20°C), mesophiles (~20–45°C), thermophiles (>45°C).Check the options for the best mesophile window.Select 25–40°C as the most appropriate concise range in the list.

Verification / Alternative check:Human pathogens (e.g., Escherichia coli, Staphylococcus aureus) are mesophiles with optima near 37°C, supporting the 25–40°C range as suitable for mesophilic growth.

Why Other Options Are Wrong:

• 20–30°C: too narrow; excludes many mesophiles that peak near 37°C.
• > 40°C: favors thermophiles rather than mesophiles.
• None of these: incorrect because 25–40°C fits standard definitions.
• 5–15°C: psychrophilic/psychrotrophic range.

Common Pitfalls:Confusing optimum with range; many mesophiles survive up to ~45°C but do not necessarily thrive beyond ~40°C.

Final Answer:25–40°C.