Controlled intra- or extracellular production of staphylococcal nuclease and ovine omega interferon in Lactococcus lactis

A system for controlled targeting of heterologous protein was developed in the food-grade bacterium Lactococcus lactis. it is composed of the L. lactis strain NZ9000 and of two broad host range expression vectors pCYT:Nuc and pSEC:Nuc for, respectively, cytoplasmic and secreted staphylococcal nuclease (Nuc) nisin-inducible production. The level of intracellular production of Nuc measured with pCYT:Nuc (3 mg l(-1)) is significantly lower than the one obtained with pSEC:Nuc (similar to20 mg l(-1)). The secretion efficiency (SE) of Nuc is estimated to be similar to70%, corresponding to similar to15 mg of secreted Nuc l(-1) . Furthermore, we established that Nuc production continued in L. lactis 10 It after a 1-h nisin-pulse induction. This system was then used for intra- and extracellular production of a protein of therapeutical interest in L. lactis, the ovine interferon-omega (IFN-omega). The SE and the quantity of secreted active IFN-omega were evaluated respectively to be similar to70% and similar to1 mg l(-1) ( - two-fold higher than the cytoplasmic form). (C) 2003 Published by Elsevier Science B.V. on behalf of the Federation of European Microbiological Societies.