Human probiotic bacteria attenuatePseudomonas aeruginosabiofilm and virulence byquorum-sensinginhibition

This work investigated chloroform extracts from culture supernatants of two human probiotic bacteria,Lactobacillus caseiCRL 431 andLactobacillus acidophilusCRL 730 for the production of virulence factors andquorum sensing(QS) interference against threePseudomonas aeruginosastrains. Both extracts inhibited biofilm biomass (up to 50%), biofilm metabolic activity (up to 39%), the production of the enzyme elastase (up to 63%) and pyocyanin (up to 77%), and decreased QS, without presenting any antibacterial acgivity. In addition, the chloroform extracts of both strains disrupted preformed biofilms of the three strains ofP. aeruginosaanalyzed (up to 40%). GC-MS analysis revealed that the major compounds detected in the bioactive extracts were four diketopiperazines. This study suggests that the metabolites ofL. caseiandL. acidophiluscould be a promising alternative to combat the pathogenicity ofP. aeruginosa.