bioreactor studies of heterologous protein production by ...

Aerobic fermentation osing iamnobihd tells can be realized in three-phase airlift
reactors. The airiin reactors provide good hydrodynamiics and mas W er
characteristics at low capital and operating costs. Undoubtedly, very efficient biologid
processes can be achieved in three-phase airlift bioreactors. ln recent years, many bench
and pilot sale applications of the three-phase airlift bioreactors have been studied over a
variety of immobilized cek nie most active area is the wastewam marnent using
immobkd heterogeneous rnicmorganisms (Fan et al., 1987; and Heijnen et al., 1990).
The foilowing sections present a brief review of some of the more ment studies involving
immo biiized ceii airlift bioreactors.
Keshavarz et al (1990) used irnmobilized Penicilüum chrysogemm P2 as a mode1
system to demonstrate the feasibility of penicillin production in a three phase airlift
reactor. Peniciltium chrysogemm P2 was immobilind on celite ad the obtained
immobiid œil slurry was introduced into a 250-320 L working volume draft tube airiift
reactor. Air flow rate was varied between 0.2 to 1.0 v.v.m. to maintain bulk liquid
circulation and the dissolved oxygen tension (DOT) above 50% air saturation. Both batch
and continuou operations wee canied out They showed that operating a large-sale
three phase airlift reactor for production of peniciIlin by Kamobilized ceils was feasible.
lmmobilued ceiis were able to maintain biasynthetic activity for long time. After 500
hours of fermentation, penicillin was stiU being synthesized, but an incnase in fne biomass
concentration was observed at later stages of operation.