Contamination of a high-cell-density continuous bioreactor.

Area of Science:

• Biotechnology
• Microbiology
• Industrial Microbiology

Background:

• Continuous fermentations are crucial for industrial microbial processes.
• Contamination by faster-growing microbes like Escherichia coli can disrupt steady-state fermentations.
• Recombinant Saccharomyces cerevisiae strains are engineered for enhanced production capabilities.

Purpose of the Study:

• To investigate the use of a flocculent Saccharomyces cerevisiae strain in continuous fermentation.
• To assess the impact of Escherichia coli contamination on the continuous culture.
• To evaluate flocculation as a selective mechanism for microbial control.

Main Methods:

• Continuous fermentation using a recombinant flocculent Saccharomyces cerevisiae in an airlift bioreactor.
• Introduction of Escherichia coli contamination during steady-state operation.
• Monitoring of microbial populations and fermentation parameters.

Main Results:

• The recombinant Saccharomyces cerevisiae, due to its flocculating property, remained in the bioreactor.
• The faster-growing Escherichia coli was washed out, indicating successful microbial control.
• High-cell-density fermentation was achieved, leading to high productivity.

Conclusions:

• Flocculation in Saccharomyces cerevisiae can serve as a selective advantage in continuous cultures.
• This property aids in maintaining monoculture and preventing contamination.
• Flocculation facilitates high-cell-density systems and enhances productivity in bioprocesses.