Multiphase Bioreactor Design

Hydrolysis of lecithin by phospholipase A2
encapsulated in lecithin/AOT/isooctane reversed
micelles

Morgado et al., 1996

Esterification of oleic acid and oleyl alcohol by a lipase-surfactant complex
in an ultrafiltration cell

Isono et al. 1998

Hydrolysis of sunflower oil by lipase in an emulsion system Can et al., 1998

Hydrolysis of Menhaden oil by lipase in a hollow fibre reactor Rice et al., 1999

Interesterification of butterfat with oleic acid by lipase in a hollow fibre
reactor

Balcão & Malcata,

1997, 1998

Synthesis of short chain esters by cutinase encapsulated in AOT/isooctane
reversed micelles

Carvalho et al., 1998

Production of hexanal from linoleic acid by the action of lipoxygenase and
hydroperoxide lyase in hollow fibre MR

Cass et al., 2000

and particularly in multiphase membrane reactors. This class of reactors, especially when
using membrane modules with a high specifie area such as hollow fibres, is ideal to
promote an interfacial contact between lipases and lipidic substrates.
In the typical multiphase membrane reactor application, the lipidic or organic phase is
passed through one side of the membrane, while a buffer solution flows tangentially on
the other side. The membrane becomes wetted by the lipidic phase if the membrane
material is hydrophobic (Figure 6.15), or by the aqueous phase if it is hydrophilic, and the
reaction takes place at the interface. The lipase is usually immobilised on the side of the
membrane that faces the hydrophilic phase, or alternatively, inside the membrane. In
certain cases the hydrophobic side can be used for immobilisation (van der Padt et al.,
1990, 1992; Janssen et al, 1991; Pronk et al., 1992). The substrates and products will
distribute themselves between the two phases according to their solubility characteristics.
Tanigaki and co-workers (1993) developed a slightly different approach by using two
different types of flat membranes in the reactor: hydrophilic and hydrophobic. The
hydrolysis of soybean oil was carried out in an enzyme chamber separated by the two
membranes with water permeating from one side through the hydrophilic membrane and
oil permeating from the other through the hydrophobic membrane. The products formed,
glycerol and fatty acids, back-diffused through the membranes to the recirculating
aqueous and oil phases.
The contact between organic and aqueous phases needed for transforming lipids can
also be promoted at a microscopic level but without phase separation at the macroscopic
level, by using reversed micellar systems. Despite of several advantages, the applications
of these systems have been mostly explored in batch reactors, at a laboratory scale.
Nevertheless, continuous processes for the hydrolysis of lipids (Chang et al., 1991;
Chiang & Tsai, 1992a, 1992b; Prazeres et al., 1992, 1993a, 1993b, 1994; Morgado et al.,
1996; Hakoda et al., 1996), and synthesis of esters (Carvalho et al., 1998) in reversed
micellar systems have been investigated in membrane reactors Despite the expectations,

Enzymatic membrane reactors 167