Unveiling the mechanism of Lonicera japonica Thunb. polyphenols against Cronobacter sakazakii from powdered infant formula by untargeted metabolomics and its application as a natural disinfectant

Contamination by Cronobacter sakazakii in powdered infant formula (PIF) and the potential hazards of chemical disinfectants are pressing issues requiring urgent resolution. This study aimed to investigate the antibacterial activity and mechanism of Lonicera japonica Thunb. polyphenols (LP) against C. sakazakii and evaluate the efficacy of LP as a natural disinfectant in inhibiting C. sakazakii in biofilms on the common contact surfaces of PIF. The results showed that the minimum inhibitory concentration and minimum bactericidal concentration of LP against C. sakazakii were 4 to 8 mg/mL and 8 to 16 mg/mL, respectively. Compared with controls, LP-treated C. sakazakii showed significantly reduced intracellular ATP and reactive oxygen species levels (P < 0.05); increases in AKP, protein, and nucleic acid leakage (P < 0.05); obvious cell membrane depolarization; enhanced membrane permeability; and irreversible cell morphological damage. Untargeted metabolomics analysis identified a total of 536 differential metabolites. Among them, 67 key differential metabolites were involved in fatty acid metabolism, amino acid metabolism, energy metabolism, membrane transport metabolism, and nucleotide metabolism, thereby disrupting the structure and function of the cell wall and cell membrane, reducing the resistance to environmental stress, and inhibiting ATP and nucleic acid synthesis. Application tests demonstrated that LP can significantly inactivate C. sakazakii in biofilms on stainless steel, glass, tinplate, and polyvinyl chloride surfaces. These findings deeply reveal the antibacterial mechanism of LP against C. sakazakii, and provide a theoretical basis for the application of LP as a natural disinfectant to reduce C. sakazakii contamination of PIF.