The Potential Role of rpoS and ompR in the Acid Resistance and Desiccation Tolerance of Cronobacter malonaticus Strains

In this study, the acid resistance and desiccation tolerance of 20 strains of Cronobacter malonaticus were explored, and their genetic variances with respect to their survival in stressful conditions were identified by genomic analysis. The strains showed significant variances in acid tolerance when exposed to simulated gastric acid (pH 3.5) for 2 h. Strain 685 demonstrated less viability, suggesting greater susceptibility. Desiccation in infant formula also yielded sub-lethally injured cells, with variable strain recovery, highlighting strain 685 as the strain with the lowest recovery. Strains were determined to contain single nucleotide polymorphisms (SNPs) in the ompR and rpoS genes, suggesting loss-of-function mutations and potentially elucidating the stress sensitivity mechanism of strain 685. This study underscores the importance of genetic factors in C. malonaticus resilience and the necessity for developed detection methods for assessing food safety risk, especially in relation to powdered infant formulas. Our results provide important information on the pathogenic potential of C. malonaticus and help guide future research priorities to mitigate risks associated with foodborne pathogens.