S28: Solving challenging DSP issues with Clean Genome host technology: case study.

Clean Genome® E. coli strains were engineered by deleting >700 genes, removing all mobile DNA elements and many unnecessary genes. The resulting strains do not lyse in culture and exhibit increased genetic stability and enhanced metabolic efficiency. The deletions tailored our gene expression system ScarabXpress-2 for high yield protein production in the fermentor. In a test system, reproducible yields of >25 g/L of soluble therapeutic protein were obtained. A scalable downstream purification process was applied to the Scarab source material and improved product purity was observed at each unit operation.   The purified protein met quality criteria.  Therefore, the reduced genome strains, including libraries of protease knockouts and strains with reduced mutation rates, represent a rational starting point for upstream process design that offers benefits to upstream and downstream processing.