48. Monod’s model for the bacterial cell growth describes a relationship between
1. Cell growth rate vs time
2. Specific cell growth rate vs substrate concentration
3. Specific cell growth rate vs product concentration
4. Log cell concentration vs time

Understanding Monod’s Model of Bacterial Growth

Monod’s model is a fundamental concept in microbiology that explains the relationship between bacterial growth and substrate concentration. This model helps in understanding microbial kinetics and is widely used in biotechnology, fermentation, and wastewater treatment.

Correct Answer: 2. Specific Cell Growth Rate vs Substrate Concentration

Monod’s equation describes how microbial growth depends on substrate availability. The specific growth rate (μ) increases with increasing substrate concentration (S) but eventually reaches a maximum rate (μmax).

Monod’s Equation:

Where:

• μ = Specific growth rate (h⁻¹)
• μmax = Maximum specific growth rate
• S = Substrate concentration
• Ks = Half-saturation constant (substrate concentration at which μ is half of μmax)

Key Relationships in Monod’s Model

Phases of Bacterial Growth Curve

1. Lag Phase: Bacteria adapt to new conditions.
2. Exponential (Log) Phase: Rapid growth with substrate availability.
3. Stationary Phase: Nutrients deplete, growth slows.
4. Death Phase: Cell death exceeds growth.

Applications of Monod’s Model

• Industrial Fermentation: Optimizing microbial growth conditions.
• Wastewater Treatment: Controlling microbial degradation of pollutants.
• Bioreactor Design: Ensuring efficient microbial productivity.

Conclusion

Monod’s model is essential for understanding microbial growth dynamics. The relationship between specific cell growth rate and substrate concentration plays a key role in various biotechnological applications.

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