Purpose: To find the key proteins involved in Cronobacter spp. biofilm formation and invasion.
Methods: Crystal violet staining and fluorescence microscopy analyses were used to compare the biofilm formation ability among different Cronobacter strains and to discover the key proteins that are involved in Cronobacter biofilm formation. Two-dimensional liquid chromatography–tandem mass spectrometry, which was coupled with isobaric tags for relative and absolute quantification (iTRAQ) labeling, was employed to quantitatively identify the proteins that were differentially expressed in the weak biofilm former C. sakazakii ATCC29544 compared to the strong biofilm former C. dubliniensis DSM 18707.
Results: In total, 1190 differentially expressed proteins were detected. Gene ontology analysis indicated that these differentially expressed proteins are related to biological binding, cell structure, signal transduction, cell adhesion, and cellular interaction. Among these differential proteins, the expression levels of 448 non-redundant proteins were altered significantly, and 177 of these proteins were differentially expressed by more than 5-fold, with 81 up-regulated proteins and 96 down-regulated proteins.
Significance: In this study, the proteins that are attributed to the differential biofilm formation of Cronobacter strains were screened using the iTRAQ approach of quantitative proteomic analysis. Several of these proteins were selected to elucidate the mechanism of biofilm formation in Cronobacter spp.