Abstract
Growth of the antibody market has fueled the development of alternative expression systems such as glycoengineered yeast. Although intact antibody expression levels in excess of 1βgβL^β1^ have been demonstrated in glycoengineered yeast, this is still significantly below the titers reported for antibody fragments in fungal expression systems. This study presents a simplified approach to estimate antibody secretion kinetics and oxygen uptake rate requirements as a function of growthβrate controlled by a limiting methanol feed rate in glycoengineered Pichia pastoris. The yield of biomass from methanol and the specific oxygen requirements predicted in this study compare well with values reported in the literature for wildβtype P. pastoris, indicating the intrinsic nature of these yields independent of glycoengineering or the heterologous protein expressed. Specific productivity was found to be a nonβlinear function of specific growth rate. Based on comparison with relationships between specific growth rate and specific productivity reported in the literature this correlation seems empirical in nature and cannot be established a priori. These correlations were then used in a simple mass balance based model to predict the cultivation performance of carbon limited cultivations under oxygen transfer limited conditions to indicate the usefulness of this approach to predict large scale performance and aid in process development. Biotechnol. Bioeng. 2010;106: 918β927. Β© 2010 Wiley Periodicals, Inc.