Salivaricin P

Lactobacillus salivarius DPC6005, a porcine intestinal isolate, produces a two-component bacteriocin, salivaricin P, with homology to ABP-118 produced by a human probiotic L. salivarius strain. Indeed, molecular characterization revealed that while the peptides Sln1 and ABP-118alpha are identical, their companion peptides (Sln2 and ABP-118beta, respectively) differ by two amino acids. This observation suggests that two-component bacteriocins may be a common feature of intestinal L. salivarius strains.

Two-component salivaricin P-like bacteriocins have demonstrated potential as antimicrobials capable of controlling infections in the gastrointestinal tract (GIT). The anti-Listeria activity of salivaricin P is optimal when the individual peptides Sln1 and Sln2 are added in succession at a 1:1 ratio. However, as degradation by digestive proteases may compromise the functionality of these peptides within the GIT, we investigated the potential to create salivaricin variants with enhanced resistance to the intestinal protease trypsin. A total of 11 variants of the salivaricin P components, in which conservative modifications at the trypsin-specific cleavage sites were explored in order to protect the peptides from trypsin degradation while maintaining their potent antimicrobial activity, were generated. Analysis of these variants revealed that eight were resistant to trypsin digestion while retaining antimicrobial activity. Combining the complementary trypsin-resistant variants Sln1-5 and Sln2-3 resulted in a MIC(50) of 300 nM against Listeria monocytogenes, a 3.75-fold reduction in activity compared to the level for wild-type salivaricin P. This study demonstrates the potential of engineering bacteriocin variants which are resistant to specific protease action but which retain significant antimicrobial activity.

The study sought to purify and characterize a novel bacteriocin from oral L. salivarius and studying the effect of L. salivarius and its bacteriocin against multidrug-resistant (MDR) P. aeruginosa in vivo and in vitro. Saliva Lactobacillus salivarius bacteriocin was prepared and purified. The molecular weight of purified L. salivarius bacteriocin was 13,500Da protein. The antibacterial activity of purified salivaricin LHM was higher than crude (P<0.05) and was active at a wide range of pH values, thermostable and has no lipid or carbohydrate moiety. The antibiofilm activity of salivaricin LHM was observed. In vivo, Lactobacillus salivarius and salivaricin LHM significantly decrease the effect of bacteria in the kidney and bladder, while there is an improvement of P. aeruginosa infection in ureter salivaricin LHM-treated groups (P<0.05). Analysis of serum IL-10 and IL-4 levels revealed salivaricin LHM has prophylaxis effect. In conclusion, salivaricin LHM is protein in nature, without lipid or carbohydrate moieties, heat-stable and active at a wide range of pH values and can be classified as type II bacteriocin. Lactobacillus salivarius and salivaricin LHM has anti-pseudomonas activity, immunomodulatory by increasing pro-inflammatory cytokines and antibiofilm against P. aeruginosa urinary tract infection model in vivo and in vitro.