Control of specific growth rate for the enhanced production of human interferon α2b in glycoengineered Pichia pastoris: process analytical technology guided approach

Abstract

BACKGROUND: Process variability in bioprocess systems involving genetically engineered strains is a common bottleneck and a real‐time insight of the on‐going process is crucial to achieve the desired product and its quality. In this study, a process analytical technology (PAT) platform was developed for the monitoring and control of specific growth rate during methanol induction phase (μₘₑₜ) of glycoengineered Pichia pastoris fermentation for human interferon alpha 2b (huIFNα2b) production. RESULTS: The PAT guided approach involves real‐time monitoring of capacitance (ΔC) facilitating online estimation of specific growth rate (μₑₛₜ), which serves as a process input during controller application. Fed‐batch experiments using pulsed‐feeding of methanol at different dosage (20\u2009g and 30\u2009g) did not significantly influence μₘₑₜ. Exponential methanol feeding was achieved using a modified proportional, integral and derivative (PID) controller for different predefined specific growth rate set point (μₛₚ) values, namely 0.015, 0.03, 0.04 and 0.06 h⁻¹. Exponential feeding strategy during the induction phase resulted in two crucial outcomes: (i) controlled methanol feeding rate (regulated by the developed PID controller) balanced the methanol consumption rate (qₛ, ₘₑₜ) of the P. pastoris; (ii) significant improvement in huIFNα2b titer (1483\u2009mg L⁻¹) and specific productivity(>0.4 mg g⁻¹. h) was achieved by the robust control of μₘₑₜ at optimal (0.04 h⁻¹) value. The purified huIFNα2b was found to exhibit antiproliferative effect against human breast cancer cell lines. CONCLUSIONS: Efficient control of μₘₑₜ at a very low narrow range was achieved with a long‐term controller stability (>10 h) and the highest titer reported to date for huIFNα2b (at optimal μₘₑₜ) in the yeast expression platform. © 2019 Society of Chemical Industry