Secretion of Homologous and Heterologous Recombinant Proteins in Escherichia Coli and Other Gram-Negative Bacteria by Using a New Secretion System

Abstract

Since Gram-negative bacteria are not able to transport proteins containing a leader sequence across the outer membrane, recombinant proteins cannot be secreted into the culture medium. On the other hand the extracellular production of overexpressed proteins is highly desirable, since downstream processing would be much easier. In recent years we developed an expression/secretion system for E. coli based on the membrane permeabilizing effect of the kil peptide of E. coli. Using this secretion system we demonstrate here the successful extracellular production of several important industrial enzymes. For some enzymes the results were confirmed bei experiments in bioreactors. Furthermore, a method was described to transfer the secretion system to other Gram-negative bacterial species. Using Klebsiella planticola and Acetobacter methanolicus it was shown that recombinant proteins can be produced extracellularly in an unexpectedly high level.