Abstract
In human lysozyme (hLYZ) production by P. pastoris, severe
reactive oxygen species (ROS) accumulation occurred during the cell
growth phase when using DO-stat control mode, leading to a limited
expression of hLYZ. In this study, a novel periodic dissolved oxygen
concentration (DO) control strategy was proposed to solve these
problems. This strategy intermittently/periodically switched the
cultivation environment from “high DO-low glycerol concentration”
(DO-stat control mode) to “low DO-high glycerol concentration” for 4
cycles. With the strategy: (1) the highest cell concentration
(~120 g-DCW L-1) with healthy and
functional skeleton was achieved at the end of cell growth phase by
controlling ROS levels below 48.35 Fluorescence intensity
g-DCW-1; (2) cells metabolic activities in the
successive induction phase were largely enhanced; (3) hLYZ activity
reached the highest level of 2.18×105 IU mL-1, which
was about 2-fold than that obtained with the DO-stat control mode, when
the same induction strategy was adopted.