Continuous cultivation start-up control--an experimental investigation

Area of Science:

• Biotechnology
• Metabolic Engineering
• Microbial Physiology

Background:

• Synchronous growth in carbohydrate-limited Saccharomyces cerevisiae cultivations can lead to instability.
• Controlling metabolic flux is crucial for optimizing yeast fermentation processes.
• Uncontrolled processes near the critical dilution rate are marginally stable and difficult to manage.

Purpose of the Study:

• To propose and experimentally investigate a control strategy to prevent synchronous growth in yeast cultivations.
• To compare the effectiveness of an adaptive controller versus a fixed parameter controller.
• To maintain a low ethanol concentration by manipulating substrate feed rate.

Main Methods:

• Experimental investigation of a control strategy for Saccharomyces cerevisiae cultivation.
• Implementation and comparison of an adaptive controller and a fixed parameter controller.
• Manipulation of substrate feed rate to control metabolic flux and ethanol concentration.

Main Results:

• The adaptive controller demonstrated superiority over the fixed parameter controller.
• The adaptive controller effectively identified process variations due to changing cell activity.
• Reproducible achievement of the desired operating point was demonstrated.
• Yeast exhibited adaptation towards increased respiratory activity under prolonged disturbances.

Conclusions:

• An adaptive control strategy is effective for managing Saccharomyces cerevisiae cultivations and preventing synchronous growth.
• Adaptive controllers offer advantages due to their ability to adapt to dynamic process conditions.
• Yeast can adapt its metabolic behavior, showing increased respiratory activity even at low ethanol concentrations.