bioreactor studies of heterologous protein production by ...

working Liquid volume. The aeration rates were kept constant at 0.6 to 1.5 Umin (0.4 to
1.0 VVM).
3.4.2. Continuous Fermentation
Continuous culture operation was uswd to investigare pldd stabiiity and recombinant
protein pmductivity because it gave rise to a relatively wen-defined, repmducible
environment and a state of baIanced growth. As the dilution rate corresponds to the
spenfic growth rate in continuous culture. it also offa a convenient way to examine the
effect of growth rate on plasmid stability, which is stül a controversial issue.
The inoculum preparation was the same as in batch fermentation and the inOCUIun
size was 10% of the bioreactor working volume for an continuous culture experiments. A
YPG non-selective complex medium (medium III) or YNB selective minimum medium (
medium 1) was used in continuous cuiture. The continuous cultures were carried out m
both airlift and stirred-tank bioreactors at 30 "C and an aeration rate of 1 VVM. The
bioreactors used were the same as desrri'bed in batch fermentation.
[n order to achieve the objectives of this part of the research, the foIiowing
experiments were performed:
1) Continuous suspension fennentatim &g nonselective medium (medium m) at
different dilution rates @ = 0.05, 0.10. 0.20, 0.25 h"). Ce& glucose. ethanol and