Impact of tolQ gene deletion on heat resilience in Cronobacter sakazakii

This is the authors' abstract. We don't add key points for this paper.

Cronobacter sakazakii is an opportunistic foodborne pathogen linked to severe neonatal infections, and its strong desiccation tolerance enables persistence in low-moisture processing environments. Its survival under sublethal, process-relevant temperatures poses a major challenge to powdered infant formula (PIF) safety. Our previous work associated elevated tolQ expression with heat tolerance in C. sakazakii , but its functional role remained unclear. ΔtolQ mutant of BAA-894 was constructed via a pTmobSacB suicide plasmid and sequence-verified to assess tolQ -mediated stress adaptation. Compared with the wild type, ΔtolQ reduced viable counts by 0.35 log CFU/mL under non-mild heat stress (NMHS; 37 °C) and 0.90 log CFU/mL under mild heat stress (MHS; 52 °C), whereas complementation restored near wild-type growth. During desiccation, the mutant showed reductions of 1.20 and 1.93 log CFU/mL under NMHS and MHS, respectively. Under acid stress (pH 3.5), it maintained viability but lacked wild-type growth increases. Flow cytometry revealed fewer membrane-intact cells, especially under MHS. Transcriptomics identified 1,894 differentially expressed genes enriched in translation, flagellar assembly, envelope integrity, carbon metabolism, and exopolysaccharide biosynthesis. These findings demonstrate that tolQ supports survival and transcriptional homeostasis under sublethal heat, highlighting its potential as a target for improving thermal control in food-processing environments.