Continuous plug-flow bioreactor: experimental testing with Pseudomonas putida culture grown on benzoate

Area of Science:

• Biotechnology
• Microbial Cultivation
• Chemical Engineering

Background:

• Batch bioreactors are common for microbial cultivation.
• Continuous plug-flow (PF) bioreactors offer potential for process intensification.
• Pseudomonas putida is a relevant microorganism for biotechnological applications.

Purpose of the Study:

• To evaluate the feasibility of a continuous plug-flow (PF) bioreactor for Pseudomonas putida.
• To compare microbial growth and substrate consumption in PF bioreactors versus traditional batch bioreactors.

Main Methods:

• Cultivating Pseudomonas putida in a continuous plug-flow bioreactor using Teflon tubing.
• Implementing simultaneous aeration of liquid medium and air to create bubbles.
• Varying residence times within the PF bioreactor.
• Comparing results to batch bioreactor cultivation.

Main Results:

• PF bioreactors achieved maximum biomass density comparable to batch bioreactors when residence time exceeded stationary phase duration.
• Complete consumption of benzoate, the sole carbon and energy source, was observed in PF mode.
• Identified drawbacks include cell aggregation leading to fluctuating outflow concentrations, significant cell adhesion to tubing walls, and insufficient aeration.

Conclusions:

• Continuous plug-flow bioreactors are feasible for Pseudomonas putida cultivation, achieving similar performance to batch systems under optimized conditions.
• Cell aggregation, wall adhesion, and aeration limitations are key challenges for practical PF bioreactor implementation.
• Further research is needed to address these limitations for efficient and stable continuous microbial cultivation.