Analysis of the inhibitory capacity of Lactobacillus plantarum on biofilm and quorum sensing signals of Pseudomonas aeruginosa

RAMOS A., ; NOSEDA DIEGO GABRIEL; BOSCH A; YANTORNO O. ; J. C. VALDEZ

Villa Carlos Paz, Cordoba

Workshop; Workshop in Current Topics in Pseudomonas and Burkholderia Research.; 2009

Sociedad de Microbiologia General

In previous works we have demonstrated that supernatants of Lactobacillus plantarum cultures (SLp), interfens with the pathogenic capacity of Pseudomonas aeruginosa, both in vitro and in vivo. The purpose of this study was to determine some of the components of SLp responsible for such interference. For this we perform the following assays with SLp: 1) determination of DL-lactic acid concentration, 2) determination of DNAase, 3) Effect of heat and proteases in the inhibitory capacity of the SLp on P. aeruginosa biofilm formation 4) Effect of SLp on P. aeruginosa acyl-homoserine lactones (quorum sensing signals) by Thin Layer Chromatography (TLC), Spectrun Fourier Transform Infrared (FT-IR), Gas Chromatography-Mass Spectrometry (GC-MS) and bioassays using the following reporter bacteria: Cromobacterium violaceum CV026, Cromobacterium violaceum Vir07, Agrobacterium tumefasciens KYC55. Results: The concentration of DL-lactic acid was 130 mM (MIC for P. aeruginosa = 100 mM). No DNase activity was detected in SLp. The heat removed the inhibitory capacity of SLp. Neutralization decreased the inhibitory capacity of SLp. Proteases inhibited P. aeruginosa biofilm increasing the inhibitory effect of SLp. The P. aeruginosa acyl- homoserine lactones remained unchanged after treatment with SLp. Conclusions: Lactic acid concentration in SLp could affect P. aeruginosa viability. Inhibition of biofilm of P. aeruginosa would be produced by a non-protein factor present in the SLp. Besides, this inhibition is not related to the biological activity or chemical structure of acyl-homoserine lactones. The putative factor could be the AI-2, a precursor or a by­product due to presence of lux S gene in L. plantarum. We are conducting studies in this regard.