Intention: Due tot he high growth potential of the White Biotechnology, we can assume an increasing demand for technical enzymes and other performance proteins. As a general rule, cost effectivly and thus competitively provided high quality proteins through the utilization of recombinant methods as well as effective and easy cleaning methods. Therefore, those processes in which the desired protein is released directly into the medium (secretion), without cell disruption, are ideal. For this purpose, the ejection of fusion proteins using E.coli K12 “leaky mutants” is to be optimized.