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

Abstract

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 (∼20 mg l-1). The secretion efficiency (SE) of Nuc is estimated to be ∼70%, corresponding to ∼15 mg of secreted Nuc l-1. Furthermore, we established that Nuc production continued in L. lactis 10 h 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-ω). The SE and the quantity of secreted active IFN-ω were evaluated respectively to be ∼70% and ∼1 mg l-1 (∼two-fold higher than the cytoplasmic form). © 2003 Published by Elsevier Science B.V. on behalf of the Federation of European Microbiological Societies.