Inactivation of Cronobacter malonaticus cells and inhibition of its biofilm formation exposed to hydrogen peroxide stress

摘要

ABSTRACTPresence ofCronobacter malonaticusin powdered infant formula (PIF) poses a high risk to infant and public health.Cronobacter malonaticushas been widely distributed in food and food processing environments, and the true origin ofC. malonaticusin PIF is poorly understood. Control and prevention ofC. malonaticusis necessary for achieving microbial safety of PIF. However, little information about decontamination ofC. malonaticusis available. In this study, effects of hydrogen peroxide on inactivation and morphological changes ofC. malonaticuscells were determined. Furthermore, inhibitory effects of H2O2on biofilm formation inC. malonaticuswere also performed. Results indicated that H2O2could completely inactivateC. malonaticusin sterile water with 0.06% H2O2for 25 min, 0.08% H2O2for 15 min, and 0.10% for 10 min, respectively, whereas the survival rates ofC. malonaticusin tryptic soy broth medium significantly increased with the same treatment time and concentration of H2O2. In addition, morphological changes ofC. malonaticuscells, including cell shrinkage, disruption of cells, cell intercession, and leakage of intercellular material in sterile water after H2O2treatment, were more predominant than those in tryptic soy broth. Finally, significant reduction in biofilm formation by H2O2was found using crystal violet staining, scanning electron microscopy, and confocal laser scanning microscopy detection compared with control samples. This is the first report to determine the effects of H2O2onC. malonaticuscells and biofilm formation. The findings provided valuable information for practical application of H2O2for decontamination ofC. malonaticusin dairy processing.