Effects of ALA-PDT on biofilm structure, virulence factor secretion, and QS in Pseudomonas aeruginosa

To investigate the effects of ALA-PDT on biofilm structure, virulence factor secretion, and quorum sensing (QS) in Pseudomonas aeruginosa. We used confocal laser scanning microscopy (CLSM), an XTT assay, scanning electron microscopy (SEM), a virulence factor assay and qRT-PCR in this study. The XTT assay showed that ALA-PDT significantly inhibited the growth of planktonic P. aeruginosa. CLSM and SEM showed that ALA-PDT destroyed both bacterial and biofilm structures. The virulence factor assay showed that pyocyanin and elastase secretion were significantly inhibited in the ALA-PDT groups. qRT-PCR assays demonstrated that ALA-PDT significantly reduced the mRNA expression of QS-related genes. ALA-PDT kills planktonic and viable biofilm-associated P. aeruginosa cells, destroys biofilm structures, reduces virulence factor secretion and affects QS system gene expression.