​Given below are different types of bacterial growth curves.​

​Which one of the following options represents all correct matches between the growth curves and the type of culture?​

Correct option is D

Curve Identification:

A: Step-like growth

• Cells divide at the same time → Synchronous culture

B: Smooth S-shaped (sigmoidal)

• Typical growth with lag, log, stationary → Asynchronous culture

C: Straight linear increase

• Constant growth rate, no lag/stationary → Continuous culture

D: Two distinct growth phases (biphasic)

• Two sugar sources metabolized sequentially → Diauxic growth

Information Booster: Bacterial Growth Curves & Culture Types

1. Synchronous Culture

   • Definition: All cells divide at the same time.

   • Growth Pattern: Step-like (staircase curve).

   • Use: Experimental studies needing uniform cell age.

2. Asynchronous Culture

   • Definition: Cells divide at different times (natural condition).

   • Growth Pattern: Smooth sigmoidal (S-shaped) curve.

   • Phases: Lag → Log → Stationary → Death.

3. Continuous Culture

   • Definition: Fresh medium continuously added, waste removed.

   • Growth Pattern: Linear/logarithmic steady state.

   • Equipment: Chemostat or turbidostat.

   • Use: Industrial fermentation, long-term studies.

4. Diauxic Growth

   • Definition: Two sugars used sequentially (e.g., glucose then lactose).

   • Growth Pattern: Biphasic with a lag between two exponential phases.

   • Example: E. coli grown in glucose + lactose medium.