Bistability in a model of microbial product formation

Area of Science:

• Biochemical Engineering
• Mathematical Modeling
• Microbial Physiology

Background:

• Industrial fermentation processes often exhibit complex kinetic behaviors.
• Microbial growth and product formation are frequently interdependent and can be subject to feedback inhibition.
• Understanding these dynamics is crucial for optimizing bioprocesses.

Purpose of the Study:

• To develop and analyze a mathematical model for continuous microbial growth with product inhibition.
• To investigate the occurrence and characteristics of multiple steady states in such systems.
• To correlate model predictions with observed kinetic instabilities in industrial fermentations.

Main Methods:

• Development of a dynamic mathematical model incorporating microbial growth, product formation, and product inhibition.
• Analysis of model steady states and their stability using mathematical techniques.
• Simulation of model kinetics to observe transient behaviors and oscillations.

Main Results:

• The model predicts two distinct, stable steady states.
• One steady state is characterized by high product and low biomass concentration, approached via oscillations.
• The other steady state shows low product and high biomass concentration.

Conclusions:

• The model successfully captures the phenomenon of multiple steady states in microbial continuous culture with product inhibition.
• Observed oscillating kinetics leading to a high-product state are consistent with industrial fermentation instabilities.
• This modeling approach provides insights into controlling and optimizing bioprocesses exhibiting complex kinetics.