Inactivation of Cronobacter sakazaki by phloretin: Molecular insights into targeting SdiA and practical applications

• Published in: Food science & technology Vol. 206; p. 116533
• Main Authors: Cao, Yifang, Zhang, Yan, Xie, Yijia, Xiao, Xinglong, Ren, Jiahao, Lou, Wenyong, Liu, Fengsong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.08.2024
• Subjects: C. sakazakii; Environmental resistance; Molecular dynamics; Phloretin; SdiA; Molecular dynamics; C. sakazakii; Environmental resistance; Phloretin; SdiA
• ISSN: 0023-6438
• DOI: 10.1016/j.lwt.2024.116533

The quorum sensing receptor SdiA is vital for the environmental resistance of Cronobacter sakazakii, facilitating its survival in powdered infant formula (PIF). In this study, a three-dimensional model of the SdiA receptor was developed, and molecular docking was used to screen inhibitors targeting SdiA. The interaction mechanisms and the blocking effect of inhibitors on quorum sensing were also validated. Among hit compounds, phloretin significantly reduced the environmental resistance of the wild type (WT) at a sub-inhibitory concentration of 0.6 mg/mL (p < 0.05), lowering the survival rates from 4.61, 5.65, and 5.32 log to 2.76, 1.30, and 1.71 log under heat, osmotic, and desiccation stress, respectively. In simulated aqueous conditions, the stability of phloretin-SdiA complex was maintained throughout over 70 ns, with van der Waals forces and electrostatic interactions crucial for its structural stability. The interactions between phloretin and SdiA lead to a discernible increase in the UV absorption and a significant quenching of the endogenous fluorescence of the SdiA protein, with the α-helical content increasing from 54.3% to 65.2%. Additionally, inoculation of 4 log10 CFU/mL of WT in dry powder materials of PIF, combined with phloretin at a concentration of 0.6 mg/mL and simulation of evaporation and drying processes, reduced WT below detection limit for enumeration. The outcomes of this study provide valuable scientific evidence and insights for developing innovative prevention and control strategies against C. sakazakii. [Display omitted] •Phloretin exhibited a strong inhibitory effect on SdiA-Mediated quorum sensing.•UV, fluorescent and CD spectroscopy confirmed the interaction of phloretin with SdiA.•Van der Waals forces contributed to structural stability of SdiA-phloretin complex.•Phloretin inactivated C. sakazakii in whey protein and oligofructose effectively.