Cell and process design for targeting of recombinant protein into the culture medium of Escherichia coli

This paper is a review of strategies to introduce protein into the liquid medium of Escherichia coli K-12 industrial production cells. The cell design strategies are generally based on one of two general mechanisms. The first strategy involves a two-stage translocation using active transporters in the cytoplasmic membrane followed by passive transport through the outer membrane. Passive transport is achieved through either external or internal destabilization of the E. coli structural components. The latter can be achieved by transplantation of destabilizing components (lysis proteins) that work by permeabilization of the outer membrane from the interior of the cell, or by using cells carrying mutations of structural components. Passive transport can also be achieved by a chemical, mechanical, or enzymatic permeabilization directed from outside the cell. The second strategy is realized through transplantation of proteins capable of active transport over one or both of the membranes. This involves the transplantation of secretion mechanisms into the K-12 cell from pathogenic E. coli as well as from other species. The process design strategies are dependent on environmental conditions and must take into account changes in physical parameters, medium design, and influx of limiting carbon source in fed-batch cultivation.