Cell-free supernatant ofStreptococcus salivariusM18 impairs the pathogenic properties ofPseudomonas aeruginosaandKlebsiella pneumonia

Abstract

M18 strain ofStreptococcus salivariusis a bacterial replacement probiotic that has been suggested for use in the oral cavity. Here, we have shown thatS. salivariusM18 cell-free supernatant reduced the growth of the two most common human pathogensPseudomonas aeruginosaandKlebsiella pneumoniaand sensitized the pathogenic bacteria to antibiotic. Besides, the supernatant inhibited biofilm formation ofP. aeruginosadrastically. For pinpointing the biomolecular changes that occurred inP. aeruginosaincubated with the probiotic supernatant, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used. Unsupervised learning algorithms, principal component analysis (PCA) and hierarchical cluster analysis (HCA), and intensity analyses of individual spectral bands exhibited comprehensive alterations in the polysaccharide and lipid contents and compositions ofP. aeruginosacultivated withS. salivariusM18 cell-free supernatant. These results indicate thatS. salivariusM18 has the potential for the prevention or alleviation of different pathogen-induced infections along with the infections of oral pathogens.