In the reactor, the yeast cells were attached to the surface
of the carrier. This carrier was a granular material consisting
of polystyrene coated with DEAE-cellulose, and was provided
by Cultort Ltd., Helsinki, Finland. The material is
non-porous and not-compressible and particle sizes range
from 0.3 to 0.8 mm. The carrier is inert and can be sterilized
at 80°C with NaOH (2% w/v). These characteristics enable
its use in a packed-bed reactor.