bioreactor studies of heterologous protein production by ...

al., 1990; Irnpooisup et ai., 1989a) and bioreactor operation modes (Hardjito et al., 1993;
Ogden and Davis, 1991; Ryti and Lee, 1988). Cumntly no effective methods an
available for cornerciai scale culture of recombinant ceh in the absence of selection
pressure (Kumar and Schuged. 1990). Investigations of the possible merits of
immobilization for these recombinant cclls are tutder way. Numemus benefits with
immobilization have been fowid. Ceii irnmobilization provides a promising alternative for
successful commercial exploitation of the enpineered organisms.
1.3. Investigations of Imrnobillzed Recombinant Yeast Systeas
irnmobilization of enzymes and cells by various methods has been widely used to inaease
biological productivity in bioreactors ( Moo-Young, 1988; Overgaard et 1, 1989).
Immobiüzed ceils have r number of advantages over k cek High cellular
concentration leading to enhanced metabolic activitits and productivity. separation of ceb
hm media facilitaring downsaeam treatment, suitability for repeated use for longer
periods enhancing process efficiency, and a stabilizing effect prolonging biocatalytic
activity are advantages of Ynrnobüized systems. Becatue of these advantages, a number of
reports about imrnobilized recombinant cellî have appeared in the liteninire. Enhanced
genetic stability, high cell concentration and expression of recombinant proteins have been
demonsaated in various recombinant cell systuns in the absence of sekction pressun
( Kumar and Schugerl, 1990 ). These reports are stunmarized in Table 13.