Page 68 - MNU microbiology theoritical 2025

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

Generation time

• In prokaryotes the generation time is also called the doubling time and is

defined as the time it takes for the population to double through one round

of binary fission.

• Bacterial doubling times vary enormously. Whereas Escherichia coli can double

in as little as 20 minutes under optimal growth conditions in the

laboratory, bacteria of the same species may need several days to double

Growth curve
• In the laboratory, bacteria are typically grown in broth contained in a tube or flask,

or on an agar plate. These are considered closed or batch systems
• As the population in a closed system grows, it follows a pattern of stages, called

a Growth Curve.

• Characterized by four distinct stages

-The lag phase

- The exponential or log phase

- The stationary phase

- The death phase

General Microbiology & Immunology (PM 401) theoretical handbook Page 57