Hydrophilic guardians: Putative core proteins unaltered by 22 gene deletions mediate desiccation resistance in Cronobacter sakazakii.

Cronobacter sakazakii is a notorious foodborne pathogen linked to severe infections in neonates, with powdered infant formula serving as a common transmission route due to its ability to survive under desiccated conditions. Understanding the molecular mechanisms underlying its desiccation resistance is crucial for developing effective control strategies. In this study, we employed comparative proteomics and hydropathy profiling to investigate putative core proteins potentially involved in desiccation resilience. Proteomic analysis of wild-type and 22 knockout strains identified 1354 proteins, of which 156 were defined as putative core proteins due to stable abundance profiles. Among these, two uncharacterized proteins, ESA_03998 and ESA_01764, exhibited strong hydrophilic properties and were predicted to be surface-associated based on signal peptide analysis. Gene knockout of ESA_03998 or ESA_01764 significantly reduced surface hydrophilicity and survival under prolonged desiccation in both PBS and milk powder matrices. Additionally, Laurdan-based membrane fluidity assays revealed increased membrane rigidification (ΔGP) in mutant strains, indicating that these proteins help preserve membrane hydration and dynamics under low-moisture conditions. These findings establish a novel link between hydrophilic putative core proteins and membrane-associated desiccation resistance in C. sakazakii, offering insights into its persistence in dry food environments and highlighting potential targets for mitigating contamination in powdered infant formula.