Involvement of PhoP/PhoQ two-component system in biofilm formation in Cronobacter sakazakii

The aim of this study was to investigated the effect of PhoP/PhoQ two component system on the biofilm formation of Cronobacter sakazakii BAA-894. Crystal violet staining assay and XTT assay showed that the biofilm biomass and the viability of biofilm cells were significantly reduced in Delta phoPQ strain, while these defects were reversed in the complementation strain Delta phoPQC. Moreover, the phoPQ gene deletion weakened the ability of BAA-894 strain to form biofilms on glass and silicon wafers, and affected the content of extracellular polymeric substance (EPS) in biofilms formed on stainless-steel plates. In addition, qRT-PCR results showed that the PhoP/ PhoQ system of C. sakazakii played roles in regulating the expression of several genes associated with flagella and cellulose biosynthesis, which are both involved in biofilm formation. These finding suggest that the PhoP/PhoQ system plays important roles in biofilm formation in C. sakazakii and the system could be considered as a potential target for developing novel alternative strategies for controlling biofilms.