Dipeptides from Lactiplantibacillus plantarum limit Pseudomonas aeruginosa pathogenesis.

Aims: Lactobacilli have drawn a great deal of attention due to the heterogeneity of their cells, as well as their remarkable ability to adapt to a range of harsh conditions. One such adaptation response by Lactiplantibacillus plantarum was forming a V-shaped cell structure in low acidic pH conditions. This study aims to identify low pH induced-biofilm formation in L. plantarum and Limosilactobacillus reuteri and their antagonistic interactions with an opportunistic pathogen, Pseudomonas aeruginosa PAO1.

Methods and results: Dual species bacterial interactions revealed a Lactobacilli biofilm-mediated suppression of PAO1 biofilms and pyocyanin pigment. Furthermore, filtrates from Lactobacilli grown at low acidic pH (pH 3.5) effectively arrest the pathogenesis of P. aeruginosa PAO1, including biofilm, swarming motility, and pyocyanin formation. Liquid chromatography-mass spectroscopy analysis revealed the presence of several Lactobacilli-secreted metabolites and dipeptides that exhibited strong LasR receptor antagonistic interactions in molecular docking analysis. Prolyl-tyrosine showed the best lasR antagonistic and PAO1 biofilm inhibitory activities of the identified dipeptides.

Conclusion: Overall, the results will contribute to the development of anti-infective drugs against P. aeruginosa using Lactobacilli secreted dipeptides. Furthermore, the investigation identifies several dipeptides that can be extracted from V-shaped Lactobacilli for antimicrobial protein therapy against P. aeruginosa and other pathogens.