Bioprocess intensification: A radical new process for recovering inclusion body protein

The successful development of a greatly simplified purification process for recombinant protein is described. The direct chemical extraction of recombinant L1 protein (the major capsid protein of human papillomavirus type 16) from cytoplasmic inclusion bodies in E. coli was demonstrated at high cell density (to OD600 = 80). Highly efficient and selective precipitation of DNA was achieved during extraction using spermine, allowing direct coupling to an immobilized metal affinity column operated in expanded bed mode (IMAC-EBA). Direct capture of the target L1 protein from the extraction broth gave an unoptimized yield of 60% with a purification factor of 10. The demonstrated process greatly simplifies the way in which protein expressed as an inclusion body can be recovered at process scale. Specifically, the new process eliminates the need for mechanical cell disruption and inclusion body centrifugation, and direct EBA capture yields partially purified protein with only two units: fermentation and expanded bed adsorption