| HOME >> BIOLOGY >> TECHNOLOGY |
Method for a Typical Culture
A frozen vial of 1 ml P. pastoris sample was inoculated into a 1 L shake flask with 150
mL Yeast Nitrogen Base (YNB)-glycerol medium. A variety of genetically engineered P.
pastoris strains were used, many of which are slow growing on methanol (muts) and engineered
to produce proteins of interest. The culture was incubated at 30C, 240 rpm, for 14 hours in an
environmental incubator shaker (New Brunswick Scientific). The entire 150 mL volume of
inoculum was transferred to a 3.3 L fermentor vessel (total volume) containing 1.5 L of basal
salts medium (see media components, Table 2) plus 4.4 mL/L trace metal solution (4). The
temperature was controlled at 30C. The dissolved oxygen was set at 30% and pH is at 5.0.
Ammonium hydroxide solution (30%) was used as the base solution to adjust the pH. After 20
hours of batch culture, the optical density (OD) reaches 42. The glycerol fed-batch process was
then initiated. The feeding medium consisted of 50% glycerol and 12 mL/L of trace metal
solution. The feed rate was 24 mL/L/h, which was adjusted automatically based on the DO
reading. DO control was maintained by the proportional integral derivitive (PID) cascade
controller, which changes the speed of agitation. Pure oxygen was automatically supplied to the
fermentor to keep the DO level at the setpoint after the agitation speed reached the maximum
allowable setpoint. After the growth phase, a half-hour carbon-source starvation period was
establish
'"/>
Source: