Biotechnological and Biomedical Applications of Magnetically Stabilized and Fluidized Beds - Porous Media: Applications in Biological Systems and Biotechnology - page 473

Immobilization of enzymes or cells in MSFBs has been a very well-accepted
method and its high potential known for some time (Webb et al. 1996).
Although the majority of enzyme and cell supports for these applications
are nonporous, there are some cases were porous media is used.
The operating principles of enzyme or cell immobilization in MSFBs are
quite simple. The first step is concerned with the selection of the appropri-
ate enzyme/cell and reaction process. As examples we may refer the use of
glucoamylase for the hydrolysis of maltodextrin (Bahar and Celebar 2000),
S. cerevisiae for ethanol fermentation (Ivanova 1996; Liu et al. 2009), lipase
to catalyze the hydrolysis of triacylglycerol to glycerol and fatty acids (Lei
et al. 2009), Thiobacillus thioparus for biodesulfurization of industrial water
(Qiu et al. 2006), horseradish peroxidase for the treatment of phenolic wastew-
ater in continuous systems (Bayramoglu and Arica 2008), and Penicillium
chrysogenum for antibiotics production (Al-Qodah 2000).
The following step is the immobilization of the enzymes/cells in a magnetic
support. These magnetic supports may present many different compositions,
but usually are based on a ferromagnetic core, covered with a layer of a cer-
tain polymer and/or some sort of epoxy resin that attaches the enzymes/cells.
Besides the examples of magnetic supports referred in Section 12.5.1, the
reader can find more detailed information in the literature (Al-Hassan et al.
1991; Liu et al. 1991, 2009; Ivanova 1996; Hristov 1999; Al-Qodah 2000;
Al-Qodah and Al-Hassan 2000; Bahar and Celebar 2000; Qiu et al. 2006;
Safarik and Safarikova 2004; Van Hee et al. 2006; Webb et al. 1996; Hristov
and Fachikov 2007; Bayramoglu and Ar ı ca 2008; Betancor and Luckarift 2008;
Lei et al. 2009). Betancor and Luckarift (2008) refer several cases concerning
also their encapsulation in silica supports.
The encapsulated enzymes and their magnetic support matrices are then
inserted in a MSBs and MFB where they are able to sustain higher flow
velocities and present all the advantages inherent to these kinds of beds, which
were referred previously.
A typical flow process using a MSB and MFBs with an immobilized enzyme
is depicted in Figure 12.8.
Many examples of immobilized enzyme/cells applications may be found
in literature, and it may be referred as typical examples: ethanol and other
fermentations (Ivanova 1996; Al-Qodah and Al-Hassan 2000; Liu et al. 2009),
antibiotics production (Al-Qodah 2000), phenol and p-chlorophenol removal
from wastewaters (Bayramoglu and Arica 2008) or its biodesulfurization (Qiu
et al. 2006), synthesis of hexyl acetate (Lei et al. 2009), glucose production
(Bahar and Celebar 2000), starch hydrolysis (Webb et al. 1996), and waste-
treatment (Karam and Nicell 1997).

12.5.2.2 Protein Purification/Adsorption

Protein purification by adsorption is one of the few “classical” applications
of MSFBs in biological and health sciences. Its use has been only moderate