bioreactor studies of heterologous protein production by ...

parameter dues were considered constant and experjmentally easily accessible. In order
to obtain the parameters associated with the glucose fermentation pathway (Y' ,Y ,
XIG
and pl, -). a complete anaembic batch fermentation was carried out using nitmgen
sparging. Then the yield coefficients (Y' and Y,,, ) were detennined from a linear
X/G
regression of glucose or ethanol to œil dry weight and the maximum specific growth rate
for glucose fermentation (pl, ,) was evaluated h m a semilogarithmic plot of cd
concentration (X) versus the (1). After Y was detennined. Y and a2 were
X/G X / G
estimated bm aerobic batch fermentation. Sirnilarly, the parameters for the ethanol
oxidation pathway (Y,,, . p~, , and as) were obtained fiom the experimental data of
oxidative growth on ethanoi. The maximum specinc pwth rate for glucose oxidation ph
, was taken from the literanire (CoppeiIa and Dhujati, 1990; Piper and Kirk, 1991).
The saturation constants 4, K2 and 4 were obtained from published data (Coppella and
Dhu jati, 1990; Sonnleitner and Kappeii, 1986). Lag time rL, was evaluated from
experimental data, which is the the required to achieve exponential growth after
inoculation. The probabiiity of plasrnid loss @) was determined hm the continuous
fermentation data according to the method dexribed in Section 4.3.3. The regdation
coefficients of the pacemaker enzyme pools (k, Rh k, and W were esiimated h m the
continuous fermentation data and were then adjusted according to published information
on yeast rnetabolic pathways (van Dedem and Moo-Young, 1973); Coppella and Dhujati,
1990; Berry and Brown, 1987).