A simple expression system for Lactococcus lactis

MARELLI, B; MAGNI, C

WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY

SPRINGER

Año: 2010 vol. 26 p. 999 - 1007

0959-3993

A new expression system that can be employed in Lactococcus lactis and Enterococcus faecalis has been constructed. It is based on the use of the chromosomal pH-controllable promoter region of the citMCDEFXG operon and the replicon of pCIT264 plasmid from L. lactis CRL264. Six regions reported as pH-inducible in L. lactis were evaluated for their ability to drive the expression of the lacLM reporter genes of pAK80 vector in order to select the expression system promoter. The highest levels of transcriptional activity and acid pH enhancement were obtained from lactococcal Pcit region. Therefore, this region was selected to design an expression system for L. lactis, and the capacity of this system was analized by expressing the soluble lactococcal enzyme CitM and the rotavirus spike-protein subunit VP8*. While in L. lactis the expression of the different genes was enhanced by the pH decrease (pH<7), in E. faecalis we obtained constitutive expression levels for the tested genes. Our results confirm the great potential of this expression system as an alternative and economic tool for the heterologous protein production of therapeutical or technological interest without inducer addition.