Figure 14.6 Schematic diagram of a
low cost bioreactor developed for plant
cell suspension cultures. Redrawn,
with permission, from Hsiao et al.
(1999). © ACS.
essentially governed by (a) product synthesis patterns (i.e. growth-associated or non-
growth associated) and (b) whether the product of interest is retained intracellularly or
secreted into the medium. Table 14.6 summarises the appropriateness of the available
options. Perfusion systems, on which comparatively little work has been performed, offer
the prospect of high cell densities and are particularly suitable for extracellular products
(e.g. Su et al., 1993, 1996). The benefits of continuous culture (single-and two-stage)
must be balanced against the sterility problems associated with extended operation. At
laboratory scale, where continuous culture is a very useful tool for collecting
stoichiometric and kinetic data (Wilson, 1980), other practical difficulties arise due to
low growth rates, foaming and wall growth and the maintenance of a representative
effluent (Sahai and Shuler, 1982, 1984; Schlatmann et al., 1996). As is evident from
Tables 14.1 and 14.2, repeated-batch (“draw-and-fill”)/semi-continuous operation has
proven extremely successful for a range of processes.
Multiphase bioreactor design 442