Process for the production of proteins by fermentation

摘要

Producing a heterologous protein (I) comprises culturing an Escherichia colistrain on a technical scale in a fermentation medium containing more than 4 mg/l calcium ions or more than 48 mg/l magnesium ions, whereby (I) is secreted into the medium, and separating (I) from the medium. The Escherichia colistrain has a mutation in the lpp gene or its promoter and comprises a (I)-encoding protein linked to a signal sequence encoding a signal peptide.