This research project is focused on the study of recombinant cell kinetics and protein production in both free and immobilized cell bioreactor systems. Building on previous work on lac gene expression, a Bacillus subtilis strain has been chosen with a plasmid for constitutive expression of a- amylase. The plasmid, pBD214, contains both the structural gene and the promoter and signal sequences for enzyme secretion. Experimental design and data gathering procedures are integrated with mathematical modeling aspects to uncover a unified picture of gene expression in recombinant cells in prototypical bioreactors. Development of products from the new biotechnology will require efficient bioreactors and an understanding of the kinetics in these reactors. The kinetics of cell growth, plasmid replication and shedding and gene expression are complex and highly coupled processes. Given the state-of- the-art, it is necessary to examine recombinant cell kinetics in different bioreactor systems to decide optimization of cell growth and product formation in a given process. Accurate, unified models would guide and accelerate process development in numerous cases but such models are currently lacking in the field. This work addresses such limitations.
