Improving phytase production in Pichia pastoris fermentations through de-repression and methanol induction...

Area of Science:

• Biotechnology
• Microbial Engineering
• Protein Production

Background:

• Pichia pastoris (Komagataella phaffii) is a methylotrophic yeast known for efficient heterologous protein secretion.
• Previous phytase production studies in P. pastoris were limited to shake flasks, not reflecting industrial-scale conditions.

Purpose of the Study:

• To optimize phytase expression and production in P. pastoris using instrumented fermenters.
• To develop and validate a kinetic model for predicting phytase production under continuous and fed-batch conditions.

Main Methods:

• Investigated phytase production in continuous culture at various dilution factors (0.5, 1, 1.5 d⁻¹).
• Developed a kinetic model using fermenter data to inform fed-batch culture design.
• Employed a two-stage fermentation strategy: glucose for biomass and de-repression, followed by methanol for induction.

Main Results:

• Identified optimal phytase productivity at a specific growth rate of 0.041 h⁻¹ through kinetic modeling.
• Achieved a 3.5-fold increase in phytase production with methanol induction compared to glucose alone.
• Reached a final phytase activity of 12.65 MU/L, a 36-fold improvement over flask fermentations.

Conclusions:

• A two-stage fermentation process (glucose for biomass, methanol for induction) is crucial for high phytase yield in engineered P. pastoris.
• The developed kinetic model accurately predicts phytase production, aiding bioprocess optimization.
• This study presents a generalizable approach for optimizing protein production in P. pastoris.