Dextranase production by recombinant Pichia pastoris under operational volumetric mass transfer coefficient (kLa) 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 (kLa) 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 MutS 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 kLa 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 kLa, 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.