Bacterial Growth Curve

• The bacterial growth curve represents the growth of a bacterial population over time in a closed system (batch culture).
• It has four distinct phases:

Lag Phase:

• • Bacteria adapt to new environment.
  • Metabolic activity is high, but cell division is minimal.
  • Synthesis of enzymes, proteins, and other molecules needed for growth.

Log (Exponential) Phase:

• • Rapid cell division and exponential growth.
  • Population size doubles at a constant rate.
  • Nutrients are abundant, and metabolic activity is at its peak.
  • Generation time (time for the population to double) is calculated in this phase.

Stationary Phase:

• • Growth rate slows as nutrient depletion and waste accumulation occur.
  • Number of new cells equals the number of dying cells.
  • Metabolic activity continues, but at a reduced rate.
  • Secondary metabolites like antibiotics may be produced.

Death (Decline) Phase:

• • Nutrients are exhausted, and toxic waste products accumulate.
  • The number of dying cells exceeds the number of new cells formed.
  • The population declines at an exponential rate.

The graph above illustrates the bacterial growth curve, showing the distinct phases:

1. Lag Phase: Initial period where bacteria adapt to the environment.
2. Log (Exponential) Phase: Rapid increase in population as cells divide at a constant rate.
3. Stationary Phase: Growth rate slows as nutrients deplete and waste accumulates.
4. Death (Decline) Phase: Bacterial cells die at an exponential rate due to unfavorable conditions.

This representation highlights the dynamics of bacterial population growth in a closed system over time.

Thank you for reading from Firsthope's notes, don't forget to check YouTube videos!