Production of a sterol esterase from Ophiostoma piceae in batch and fed-batch bioprocesses using different Pichia pastoris phenotypes as cell factory.

The potential biotechnological applications for the Ophiostoma piceae sterol esterase (OPE) are conditioned to the availability of high enzyme amounts at low prices. This enzyme is a versatile biocatalyst with different biotechnological applications. In this work a systematic study on its heterologous production in different Pichia pastoris strains and operational strategies is presented. The best results were obtained using an AOX1 defective yeast strain in a fed-batch bioprocess using methanol as inducer substrate at a set point of 2.5 g L(-1) and sorbitol as cosubstrate by means of a preprogramed exponential feeding rate at a μ = 0.02 h(-1) , reaching 30 U mL(-1) of enzyme and a volumetric productivity of 403.5 U L(-1) h(-1) . These values are twofold higher than those obtained with a Mut(+) phenotype using methanol a sole carbon source. OPE was the main protein secreted by the yeast, 55% for Mut(s) versus 25% for Mut(+.)