Industrial production of heterologous proteins by fed-batch cultures of the yeast Saccharomyces cerevisiae.

This review concerns the issues involved in the industrial development of fed-batch culture processes with Saccharomyces cerevisiae strains producing heterologous proteins. Most of process development considerations with fed-batch recombinant cultures are linked to the reliability and reproducibility of the process for manufacturing environments where quality assurance and quality control aspects are paramount. In this respect, the quality, safety and efficacy of complex biologically active molecules produced by recombinant techniques are strongly influenced by the genetic background of the host strain, genetic stability of the transformed strain and production process factors. An overview of the recent literature of these culture-related factors is coupled with our experience in yeast fed-batch process development for producing various therapeutic grade proteins. The discussion is based around three principal topics: genetics, microbial physiology and fed-batch process design. It includes the fundamental aspects of yeast strain physiology, the nature of the recombinant product, quality control aspects of the biological product, features of yeast expression vectors, expression and localization of recombinant products in transformed cells and fed-batch process considerations for the industrial production of Saccharomyces cerevisiae recombinant proteins. It is our purpose that this review will provide a comprehensive understanding of the fed-batch recombinant production processes and challenges commonly encountered during process development.