Ultrafiltration and microfiltration are frequently used to
remove low molecular mass, inhibitory compounds from the
growth medium, but the necessary hydraulic flux often results
in membrane fouling, particularly at higher cell concentrations
(Fuchs et al. 2002). In contrast, single-vessel dialysis fermentors
are very efficient in continuously removing low molecular
mass by-products during cultivations, while biomass can be
supplied concurrently with substrate (Märkl et al. 1990).
Dialysis mass transfer does not require hydraulic flow across
the membrane; hence, fouling will not occur swiftly. Using a
dialysis membrane reactor, Escherichia coli could be grown to
cell concentrations as high as 174 g/L DCW (Märkl et al.
1993). Prokaryotes with typically low biomass yields in fermentations,
such as the hyperthermophile, anaerobic Archaea
Pyrococcus furiosus, the thermoacidophile Sulfolobus
shibatae, and the halophile isolate Marinococcus M52, could
also be grown to substantially higher cell concentrations using
this cultivation strategy (Krahe et al. 1996). Furthermore, the
system was suitable to obtain high cell density mammalian
cell cultures