Finished Projects of Enzyme Reactions and Bio-Separations

Enzymatic conversions in highly concentrated reaction systems

The enzymatic hydrolysis of starch is usually carried out in a batch reactor with a typical starch content that varies between 30 and 40 w/w %. Working with higher starch concentrations and thus lower water concentrations has several advantages, e.g. high reaction rates, lower energy costs, high production per amount of volume and increased enzyme stability. Higher concentrations are possible, however, novel reactor concepts need to be developed.

The aim of this project is to investigate the fundamental processes that take place during the enzymatic hydrolysis of starch at highly concentrated reaction conditions leading to the desired product composition. The information gathered during this investigation will be used to develop and test a suitable reactor concept.

Enzymatic synthesis under high pressure

In many industrial synthesis processes (e.g. polymerisation reactions), high pressure is used as an important system parameter to control the reaction. High pressures have not been widely used for synthetic purposes in biocatalytic processes since very high pressures (in the order of hundreds of MPa’s) are needed. Until recently this was very difficult to achieve on a technical scale. In recent years, a number of developments have led to a potential in this field. First, the development of mild microbial inactivation methods has initiated the development of robust reaction vessels that combine a cost-effective application of high pressures with robust and reliable operation. Secondly, the continuous exploration of our natural resources yields a continuous supply of new enzymes that can function under extreme circumstances. Of particular interest is the group of barotolerant enzymes.

It is the aim to study the behavior of enzymatic reactions under high pressure in order to show a significant improvement in yield, composition and reaction rate. Experimental values will be compared to thermodynamic calculations.

Enzymatic synthesis and separation in microreactors

Microtechnology has been applied to chemical and biochemical analysis, biosensors, DNA- hybridization and also to enzymatic conversions. Examples of enzymatic reactions on micro-scale are the use of glucose oxidase for glucose determination, polyphenol oxidation for high-throughput screening and cascade reactions for complex synthetic pathways. In this project we aim at the development of a microreactor where an enzymatic reaction is integrated with an efficient separation process. A comparison will be made between these microreactors and conventional reactor systems.

This project is a collaboration between organic chemists from Wageningen University & Research and the University of Nijmegen and electrical and computer engineers from IMS Fraunhofer Institut Duisburg.

Microreactors II

Microtechnology is finding more and more applications e.g. in chemical and biochemical analysis, biosensors, and also in enzymatic conversions. We aim at the development of a microreactor for enzymatic conversions and we are working on the comparison between enzyme reactions in microreactors and conventional reactor systems. We also study the integration of the enzymatic reaction with an efficient separation process.

Selective oligosaccharide production

Oligosaccharides, which can be used as prebiotics, are often manufactured through enzymatic synthesis. Most processes use glycosidases for transglycosylation of disaccharides. Specific oligosaccharide synthesis reactions can be achieved by using e.g. glycosynthases instead of glycosidases for transglycosylation, however, this is not yet cost effective. The lack of diversity of the available catalysts is an important bottleneck in making more complex oligosaccharides. The production of specific oligosaccharides could be improved by introducing a highly specific, in-line isolation of the product. In nature, several peptides are known that show a high complexation affinity towards specific oligosaccharides. In this project we will use the specific binding capacity of proteins e.g. lectins.