Page 54 - MNU microbiology theoritical 2025

General Microbiology & Immunology (PM 401) Second level Semester 4 2024/2025

1- Psychrophiles (cold lover)

• The psychrophiles are cold lovers, a growth range of -0 C to 15 C.
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• Non can live in the human body, but some are known to cause

spoilage of refrigerated foods

e.g Flavobacterium sp.

2- Mesophiles
• Include most bacteria and grow best between 25 and 40ºC.

• Human pathogens: most grow best near human body temperature (37 ºC).

eg. Pseudomonas aeruginosa

3- Thermophiles

• Organisms grow at optimum temperatures of 50°C - 65 °C

• They adapted to live in sunlit soil, compost piles, and hot

springs.

e.g Bacillus sterothermophilus

4- Hyperthermophiles (Extreme thermophiles)
• They are characterized by growth ranges from 80 °C to 113

°C

• Most live in volcanic vents & hydrothermal vents at the

bottom of the ocean

e.g Thermus aquaticus

General Microbiology & Immunology (PM 401) theoretical handbook Page 43