Bioprocess and enzyme technology

Bioprocess and Enzyme Technology

Associate Professor Knut Olav Strætkvern

The manufacture of products from microorganisms, cells, tissues and plants involves a number of several gentle procedures designed to conserve the structure and functions of valuable biomolecules. In biotechnology, this refers to various types of active proteins. Bioprocess technology (BPT) converts good product ideas to industrial reality. Students may easily be linked to research projects in BPT through their project assignments. This kind of student work has given valuable results.

Relevant courses: 5BT200 Bioprocess Technology (autumn) and 5BT210 Industrial Biotechnology (spring)

Methods:

1. The fermentation of microorganisms

2. The isolation of biomolecules and proteins, based on selective separation (adsorption, membranes)

3. The use of enzymes in biomass preparation (for example bioethanol)

4. Optimisation and simulation of industrial bioprocesses

At Hedmark University College, we concentrate especially on the aspects of BPT that involve the isolation and separation of valuable proteins. We have studied the extraction of potato proteins for use in food, so-called industrial proteins. For the efficient isolation of industrial proteins, chromatography and membrane filtering are used. Optimisation is first carried out in small units and volumes (10-100ml) before being tested on a pilot scale of 1-10 litres. Fermentation is the cultivation of microorganisms in controlled environments. We use fermentation both to increase cell mass for protein cleaning, and to study bacterial ecology in continuous cultivations.

Projects:
Chromatography for large scale extraction of potato protein.

Potatoes contain little protein (2 per cent) compared to starch, but on the other hand they are rich in nutrients and very effective. It may therefore prove profitable to extract the proteins from the waste and upgrade them to useful products for food and health products. Chromatography can be used both in packed columns and as expanded bed adsorption (EBA). The laboratory has extensive experience in the use of EBA with heavy adsorbents to process potato water from starch production. The columns range from 10ml up to 50 litres and the method has proved to yield proteins of very high quality. The challenge of large scale chromatography is to develop robust processes able to extract large volumes of protein (in kg) using the simplest technology possible, and at the same time separate unwanted compounds. The project will develop methods to improve the productivity of proteins in both packed columns and in EBA.

Membrane technology in protein separation

Filtration is about separating compounds in two fluid phases by means of a permeable membrane or filter mesh. In BPT, tangential flow filtration (TFF) is a frequently used technique for separating small and large compounds from each other in large volumes. Compared to chromatography, TFF is a technique capable of handling large volumes, but with limitations when it comes to separating compounds of similar sizes. Starting with potato water, we look at different strategies for attaining good protein quality and valuable fractions based on membrane filtering. We use TFF systems with membrane areas ranging from 50 cm2 to 1000 cm2.

Both project areas are run in close cooperation with HOFF Norske potetindustrier (HOFF Norwegian potato industries, www.hoff.no) as part of an ongoing product development scheme.

Other collaborators: University of Wageningen, NL, (Prof. H. Gruppen)

Centre for Food Science & Technology, Univ. Of Maryland Eastern Shore, MD (Dr. J. G. Schwarz)

Cellulose-converting enzymes in elks

In the winter, elks primarily feed on small branches deciduous tree and top shoots from pine, in other word biomass containing high values of lignocelluloses. For these large animals to be able to generate the necessary energy from this scanty diet, an efficient enzyme system is crucial. Enzymes in the elk’s digestion system must free large quantities digestible sugars from cellulose. We are in the process of locating such enzymes from the stomach contents of elks killed in road accidents. The enzymes are identified both in stomach juice and from isolated microorganisms. The aim of this work is to identify enzymes that may prove commercially useful for extracting sugar from cellulose, both at protein and DNA level. Sugar then forms the raw material for a rapidly growing fermentation industry for the production of an environmentally sustainable fuel, namely bioethanol. This research is carried out in close collaboration with the biotechnology company TransHerba AS and Professor Vidar Bakken at the University of Bergen.

Other focus areas: Plant polyphenols in interaction with protein. Fermentation in continuous mono and mixed cultures (lactic bacteria, gut bacteria models). Immobilised ethanol reaction. Isolation and characterisation of Cry-protein from genetically modified corn.