Potential and Scale-Up of Pore-Through-Flow Membrane Reactors for the Production of Prebiotic Galacto-Oligosaccharides with Immobilized β-Galactosidase

Abstract

The production of prebiotics like galacto-oligosaccharides (GOS) on industrial scale is becoming more important due to increased demand. GOS are synthesized in batch reactors from bovine lactose using the cost intensive enzyme β-galactosidase (β-gal). Thus, the development of sustainable and more efficient production strategies, like enzyme immobilization in membrane reactors are a promising option. Activated methacrylatic monoliths were characterized as support for covalent immobilized β-gal to produce GOS. The macroporous monoliths act as immobilized pore-through-flow membrane reactors (PTFR) and reduce the influence of mass-transfer limitations by a dominating convective pore flow. Monolithic designs in the form of disks (0.34 mL) and for scale-up cylindric columns (1, 8 and 80 mL) in three different reactor operation configurations (semi-continuous, continuous and continuous with recirculation) were studied experimentally and compared to the free enzyme system. Kinetic data, immobilization efficiency, space-time-yield and long-term stability were determined for the immobilized enzyme. Furthermore, simulation studies were conducted to identify optimal operation conditions for further scale-up. Thus, the GOS yield could be increased by up to 60% in the immobilized PTFRs in semi-continuous operation compared to the free enzyme system. The enzyme activity and long-time stability was studied for more than nine months of intensive use.

Wall‐Immobilized Biocatalyst vs. Packed Bed in Miniaturized Continuous Reactors: Performances and Scale‐Up

“…In addition to these conventional technologies (Figure 2), examples of membrane processes with immobilized enzymes on the surface or/and in the pores have been presented in the literature. The examples found mainly have disc shaped reactors, macroporous materials are selected for their nonlimiting diffusion rate for this process configuration, [71,72] but recent reports have also presented nanofibrous membranes as offering an higher enzyme load capacity. [73] However, one of the major issues with these systems is the energy required to ensure sufficient backpressure for the fluid to flow through the membrane.…”

What’s new in flow biocatalysis? A snapshot of 2020–2022

“…The integration of membranes in a biocatalytic reactor allows to keep the bulk of two reactants separated, thus preventing side reactions, or to selectively remove the products, circumventing thermodynamic equilibrium. MRs are an option for the conversion of large molecular size substrates; in this case, the membrane retains not only the enzyme, but also the unreacted starting material (Pottratz et al, 2022). Several factors are involved in the reactor selection and operation mode, being productivity (amount of product per unit of reactor volume and unit of time) and product-to-biocatalyst ratio (amount of product per unit of biocatalyst) the most important from an applicative standpoint (Grubecki and Kazimierska-Drobny, 2019;Carrazco-Escalante et al, 2021;Lindeque and Woodley, 2022).…”

Potential of Integrated Semi‐Continuous Enzymatic Synthesis and Filtration Processes for Efficiency Enhancement

“…The sugar composition in the course of reaction was adequately recorded by regular sampling at defined times. Generally, the taken samples were immediately thermally treated in a 95 °C water bath for 5 min to inactivate the enzyme prior to HPLC analysis as described in [24]. 3 Results and Discussion…”