Aims: To exploit promoters involved in production of the bacteriocin sakacin P for regulated overexpression of genes in Lactobacillus plantarum C11.
Methods and results: Production of sakacin P by Lact. sakei LTH673 is controlled by a peptide-based quorum sensing system that drives strong, regulated promoters. One of these promoters (PorfX) was used to establish regulated overexpression of genes encoding chloramphenicol acetyltransferase from Bacillus pumilus, aminopeptidase N from Lactococcus lactis or chitinase B from Serratia marcescens in Lact. plantarum C11, a strain that naturally possesses the regulatory machinery that is necessary for promoter activation. The expression levels obtained were highly dependent on which gene was used and on how the promoter was coupled to this gene. The highest expression levels (14% of total cellular protein) were obtained with the aminopeptidase N gene translationally fused to the regulated promoter.
Conclusions: Sakacin promoters permit regulated expression of a variety of genes in Lact. plantarum C11.
Significance and impact of the study: This study shows the usefulness of regulated bacteriocin promoters for developing new gene expression systems for lactic acid bacteria, in particular lactobacilli.