Figure 6.

Change of cell size and complexity, UPR up-regulation and viability during cultivations of P. pastoris strains producing different recombinant proteins. The P. pastoris strains producing EcPGA (A), CaLB (B), or TlXynA (C), as well as a control non-production strain (D) were cultured under the same cultivation conditions (30°C, pH 5.5), maintaining the specific growth rate of biomass with methanol at 0.016 h⁻¹. Additionally, the P. pastoris strain producing CaLB was cultured at 30°C, pH 5.5 and at a specific growth rate of biomass with methanol of 0.008 h⁻¹ (E) and 0.032 h⁻¹ (F). The four sub-populations identified with the PCA of the flow cytometric data were observed in all the cultivation processes: smaller and less complex viable cells with no UPR up-regulation (red ovals); larger and more complex viable cells with no UPR up-regulation (green ovals); viable cells with up-regulated UPR (black ovals); and cells with an impaired viability (blue ovals).