COST EXPERIENCES WITH BIOREACTORS

Abstract

Mass propagation through use of labour-saving techniques such as bioreactors and use of temporary immersion systems (TIS) has been the theme of several European network Actions through COST since 1982. Presently the working group dedicated to this field is named Advanced Regeneration in vitro. We meet once a year to discuss our results and experiences and plan new collaboration within this important field. In 2001, we arranged the first international symposium dedicated to mass propagation in liquid cultures, which resulted in an edited book on the subject (Hvoslef-Eide and Preil, 2005). Over the years, a lot of expertise and knowledge have been collected in the COST groups and the presentation will include these acquired experiences on use of simple and advanced (computer-controlled) bioreactors, as well as more simple temporary immersion systems. This paper will take some examples from this work to illustrate the progress made in these working groups. At the Norwegian University of Life Sciences (formerly the Agricultural University of Norway), we used the various COST actions and the knowledgeable participants to gain enough knowledge and confidence to construct and build our own bioreactors in 1992. These were especially designed for plant cell growth and regeneration into somatic embryos with low shear forces and few problems with cell growth accumulating on the electrodes and oxygen supplies (Hvoslef-Eide et al., 2005). There are especially two features in our bioreactors worth highlighting: (1) To reduce shear forces, we have designed the impellers to change direction at given intervals, this reduces the need for high speeds to keep a good movement in the suspension and also reduces the possibilities for cells to find quiet zones where they can settle and grow. (2) The oxygen supply is through thin-walled silicone tubes connected in loops with an inlet and an outlet through the lid. These tubes are hanging loose under the lid and move with the suspension, and no cells settle to clog these. We have used these six identical bioreactors for plant cell research with the aim to mass propagate with little labour input for 10 years (1992- 2002). Now they are used for optimalisation of micro algae growth under controlled conditions.