The Role of in Stress Adaptation and Virulence in BAA-894.

, an emerging foodborne pathogen that was isolated primarily from powdered infant formula, poses an important issue in food safety due to its high stress tolerance and pathogenicity. The Hpr (encoded by gene) has been shown to regulate carbon metabolism as well as stress response and virulence. However, the functional properties of in have not been investigated. In this study, we clarified the role of in the stress response and virulence, and explored its possible regulatory mechanism by RNA-seq. Compared with wild-type, the Δ mutant showed a slower growth rate in the log phase but no difference in the stationary phase. Moreover, the resistance to heat stress (65 °C, 55 °C), simulated gastric fluid (pH = 2.5), biofilm formation and adhesion to HT-29 cells of Δ mutant were significantly decreased, whereas the oxidative resistance (1, 5, 10 mM HO), osmotic resistance (10%, 15%, 20% NaCl), and superoxide dismutase activity were enhanced. Finally, RNA-seq analysis revealed the sulfur metabolism pathway is significantly upregulated in the Δ mutant, but the bacterial secretion system pathway is dramatically downregulated. The qRT-PCR assay further demonstrated that the Δ mutant has elevated levels of genes that are related to oxidative and osmotic stress (, , /, ). This study provides a great understanding of the role of in diverse stress responses and virulence in , and it contributes to our understanding of the genetic determinant of stress resistance and pathogenicity of this important foodborne pathogen.