Membrane Bioreactor for Simultaneous Synthesis and Fractionation of Oligosaccharides

Area of Science:

• Biotechnology
• Food Science
• Chemical Engineering

Background:

• Galacto-oligosaccharides (GOS) are valuable prebiotics derived from lactose.
• Enzymatic synthesis of GOS can be limited by product inhibition and unfavorable thermodynamics.
• Membrane bioreactors offer potential for integrated reaction and separation to overcome these limitations.

Purpose of the Study:

• To investigate the integration of selective mass transport and enzymatic synthesis in a membrane bioreactor for GOS production.
• To evaluate the impact of operating parameters like pressure and crossflow velocity on bioreactor performance.
• To determine the effect of simultaneous synthesis and fractionation on GOS yield and composition.

Main Methods:

• Enzymatic synthesis of GOS from lactose using beta-galactosidase in a membrane bioreactor.
• Utilized cellulose acetate membranes for sugar fractionation.
• Varied operating conditions including pressure (20-24 bar) and crossflow velocity (1.7-2.4 m/s).
• Analyzed the retention characteristics of different sugars and the enzyme.

Main Results:

• Simultaneous GOS synthesis and fractionation increased GOS production by 60% compared to reactions without permeation.
• Membrane selectivity showed significant changes during synthesis, retaining GOS-3 completely and GOS-2 at 80%.
• Bioreactor performance, specifically GOS synthesis-hydrolysis, was dependent on crossflow velocity at 20 bar but less so at 24 bar.

Conclusions:

• Integrating selective mass transport with enzymatic GOS synthesis in a membrane bioreactor significantly enhances GOS yield.
• The membrane bioreactor system demonstrates effective fractionation of GOS and other sugars during synthesis.
• Optimized operating conditions, particularly pressure, can influence the efficiency of simultaneous synthesis and fractionation.