Heterologous Protein Expression
Heterologous protein expression has been the foundation of the industrial and pharmaceutical biotechnology industries over the past 30 years. There are a wide variety of production platforms now commercially available and an increasing number under development encompassing different host cells, expression systems, and methods for utilizing the genetic instructions, as well as bioprocessing strategies that take advantage of the particular combinations to maximize volumetric productivity and product quality. It is generally accepted that there is no single, universal heterologous expression system and bioprocess strategy that will work for all proteins and that each protein product needs to be considered individually, based on the specific protein product, unique quality specifications, and intended application. Here, we describe some of the different cell-based and cell-free protein expression platforms for bioreactor-based production of heterologous proteins, an overview of how they work and how they have been used, and the potential advantages and disadvantages when compared with alternative approaches.