Dextranase production by recombinant Pichia pastoris under operational volumetric mass transfer coefficient (k_La) and volumetric gassed power input (Pg/V) attainable at commercial large scale

Abstract

Most of the reported bioprocesses carried out by the methylotrophic yeast Pichia pastoris have been performed at laboratory scale using high power inputs and pure oxygen, such conditions are not feasible for industrial large-scale processes. In this study, volumetric mass transfer (k_La) and volumetric gassed power input (Pg/V) were evaluated within values attainable in large-scale production as scale-up criteria for recombinant dextranase production by Mut^S P. pastoris strain. Cultures were oxygen limited when the volumetric gassed power supply was limited to 2 kW m⁻³. Specific growth rate, and then dextranase production, increased as k_La and Pg/V did. Meanwhile, specific production and methanol consumption rates were constant, due to the limited methanol condition also achieved at 2 L bioprocesses. The specific dextranase production rate was two times higher than the values previously reported for a Mut⁺ strain. After a scale-up process, at constant k_La, the specific growth rate was kept at 30 L bioprocess, whereas dextranase production decreased, due to the effect of methanol accumulation. Results obtained at 30 L bioprocesses suggest that even under oxygen-limited conditions, methanol saturated conditions are not adequate to express dextranase with the promoter alcohol oxidase. Bioprocesses developed within feasible and scalable operational conditions are of high interest for the commercial production of recombinant proteins from Pichia pastoris.

Keywords:

• Dextranase
• large-scale bioprocess
• methanol utilization phenotype
• oxygen-limited conditions
• recombinant proteins
• scale-up

Acknowledgments

Authors acknowledge technical support from Planta Piloto staff at the Instituto de Biotecnología (UNAM, México): V. Albiter, M. Caro and R. Tinoco. Also, thanks to E. Reynel for the determination of methanol in samples by GC. Special thanks to ALOPROT SA de CV (Aguascalientes, Mexico) for providing the recombinant yeast strain for the study.

Disclosure statement

The authors declare that they have no conflict of interest.

Additional information

Funding

This work was supported by the Consejo Nacional de Ciencia y Tecnología (CONACYT) under Grant No. [333744].