Reaction and diffusion in a gel membrane reactor containing immobilized cells

Area of Science:

• Biochemical Engineering
• Biotechnology
• Chemical Engineering

Background:

• Diffusion and cell distribution significantly impact gel-immobilized cell systems.
• Understanding these factors is crucial for optimizing bioreactor performance.
• Heterogeneous cell distribution and diffusional limitations pose challenges in current systems.

Purpose of the Study:

• To develop and validate a gel membrane reactor for studying immobilized cell systems.
• To investigate the effects of diffusional limitations and heterogeneous cell distribution.
• To determine kinetic parameters and diffusion coefficients in gel-immobilized systems.

Main Methods:

• Construction of a gel membrane reactor with immobilized cells between two well-mixed chambers.
• Utilizing a mathematical model incorporating time- and position-dependent cell concentration and diffusion coefficient.
• Experimental analysis of substrate and product concentrations at the gel surface.
• Microscopic analysis of cell distribution within the gel matrix.

Main Results:

• The gel membrane reactor provides direct information on substrate and product concentrations at the gel surface.
• Experimental data show a decrease in the effective diffusion coefficient of glucose with increasing yeast cell concentration in alginate gel.
• Mathematical modeling allowed for the determination of kinetic parameters.
• Microscopic analysis confirmed cell proliferation in the outer layer of the gel matrix, aligning with model predictions.

Conclusions:

• The gel membrane reactor is a valuable tool for studying diffusion and reaction kinetics in gel-immobilized cell systems.
• Cell concentration directly influences the effective diffusion coefficient of substrates within the gel matrix.
• The developed model and reactor system offer insights into the physiology of gel-entrapped microorganisms.