Sakacin G is the main responsible bacteriocin for the anti-listerial activity of meat-borne Lactobacillus curvatus ACU-1

The present study was conducted to quantify the expression of the sakacins produced by Lactobacillus curvatus ACU-1, a strain isolated from artisanal dry fermented sausages of Argentina. Polymerase chain reaction (PCR) screening indicated the presence of sakacin G, P, and Q genes in L. curvatus ACU-1. Purification and activity assays determined that anti- Listeria activity was mainly associated to sakacin G, as mass spectrometry analysis revealed a single peak of 3832.60 Da. Further characterization by quantitative PCR demonstrated that L. curvatus ACU-1 transcription of the sakacin G structural gene was three orders of magnitude higher than the others. Interestingly, L. curvatus ACU-1 had skgA1 / skgA2 as well as sppQ genes encoded in a plasmid, while the sppA gene that encodes for sakacin P was present in the bacterial chromosome. These results point out that sakacin G is the main peptide responsible for the anti-listerial activity of L. curvatus ACU-1, with little or no contribution of sakacin P and sakacin Q. The high level of expression of sakacin G demonstrated in the present work would facilitate its potential use in food preservation, improving the food quality, safety, and shelf life. In addition, the sakacin G promoter may serve as an interesting tool for the expression of other bacteriocins at higher levels.