AN ESCHERICHIA-COLI HOST STRAIN USEFUL FOR EFFICIENT OVERPRODUCTION OF SECRETED RECOMBINANT PROTEIN

Periplasmic secretion of overexpressed Bacillus stearothermophilus alp ha-amylase was analyzed in batch and fed-batch cultivations of Escheri chia coil MG1655:pCSS4-p and the mutant strain CWML2:pCSS4-p. Under al l conditions investigated, growth and product formation of MG1655:pCSS 4-p were severely impaired by heterologous protein expression and/or p rocessing, while E. coli CWML2:pCSS4-p was found to be more robust and to accumulate 2- to 3-fold higher maximum alpha-amylase levels. While this strain is itself potentially interesting for applications, its p roperties also illustrate the potential of the selection procedure tha t was employed to obtain it from its progenitor MG1655 (Weikert, C., S auer, U., Bailey, J. E., 1997. Microbiol. 143: 1567-1574. Application of this procedure to existing industrial strains may lead to significa ntly improved process organisms. (C) 1998 John Wiley & Sons, Inc.