Short communication: Roles of outer membrane protein W on survival, cellular morphology, and biofilm formation of Cronobacter sakazakii in response to oxidative stress

Cronobacter species are a group of opportunistic foodborne pathogens that cause rare but severe infections in neonates. Tolerance to environmental stress in Cronobacter is known; however, factors involved in oxidative stress are undefined. In this study, Cronobacter sakazakii survival, cellular morphology, and biofilm formation in response to oxidative stress were evaluated between the wild type (WT) and an outer membrane protein W (OmpW) mutant. The survival rates of Delta OmpW strain after treatment with 1.0 and 1.5 mM hydrogen peroxide were significantly reduced compared with those of WT. Morphological changes, including cell membrane damage arid cell fragmentation, in Delta OmpW were more predominant, than those in WT. By crystal violet staining, we also observed increased biomass in Delta OmpW biofilms as compared with WT following treatment with 0.5 and 1.0 in M H2O2. Biofilms using scanning electron microscopy and confocal laser scanning microscopy further confirmed the structural changes of biofilrns between WT and Delta OmpW in response to oxidative stress. The current findings show that OmpW contributed to survival of planktonic cells under oxidative stress and the deletion of OmpW facilitated the biofilm formation in C. sakazakii to adapt to oxidative stress.