bioreactor studies of heterologous protein production by ...

5) To make a cornparison between the airlift and stined-tank bioreactors and investigate
the possibiiity of application of airiift bionxctor for recombinant yeast fermentation.
6) To off' a basis for cornparison of immobilization system.
3.4.1. Batch Fermentation
The recombinant yeast was maintained at 4 OC on slants of maltose selective solid agar medium
(medium V). Inoculum was p wn in th& YNB selective soiid agar medium (medium IV) in
shake &sks as 30°C and 200 rpm for 36 houn and the inocuhun sh was 5% of the bioteanor
working volume for an batch culture experiments. A non-selative cornplex medium (medium
III), the yeast extract-peptone-glucose (YPG) medium (Barnen et ai.. 1983). was used in batch
fermentations. The batch culture was carried out in an airlift bioreactor at 30 O C and an aeration
rate of 1 VVM (volume per volume of medium per minute). A split column airiift bioreactor
with an inner diameter of 6.5 cm and aspect ratio of 7 was used as a culture vessel. A
6.5~28~5 cm baMe was set in the middle of the colm to form the riser and downcomer
sections. The working liquid volume Ui the reactor was 1200 mL. The clearance between
the sparger and the bonom of banle was 6.5 cm. The distance between the liquid surface
and the top of the banle was 6.5 cm. The pH and dissohed oxygen were monitored by
the Ingold pH and DO probes during the fermentation process. Fermentation profiles
were obtained by andyzing ceiï mas. glucose, ethano1 and gïucoamylase concentrations
and fraction of piasmid-bearing œUs. Batch fermentations were also performed in a
stirred-tank bioreactor (New Brunswick, Mode1 19) at 30 "C, The bioreactor had a 1.5 L