Hydrostatic pressure boost rate and mode to enhance sterilization mediated by GroEL-interacting proteins

Abstract

High hydrostatic pressure (HHP) is a new type of non-thermal food processing technology that is very important for ensuring the safety and quality of food. However, the biological molecular mechanism of HHP sterilization remains unclear. Here, our study explored the sterilizing effects of different HHP-boosting processes (boost mode and rate) on Escherichia coli O157:H7 and elucidated the biological mechanism based on the GroEL protein and its interacting proteins. First, the effects of different boost modes and rates on the bactericidal effect of E. coli O157:H7 were analyzed. The results showed that the bactericidal effect of the linear and fast boosting treatment was the most significant, and the expression of the GroEL protein in E. coli O157:H7 also increased under all four different boost modes and rates. The proteins that interacted with GroEL under different boost modes and rates were obtained and analyzed by immunoprecipitation and mass spectrometry (MS). The differences in the metabolic pathways of the E. coli O157:H7 stress response induced by different boosting methods and rates were analyzed. The results of the KEGG pathway analysis indicated that these interacting proteins were involved in 42 metabolic pathways mainly concentrated in ribosome, ABC transporter, oxidative phosphorylation and sulfate assimilation and cysteine biosynthesis. According to the difference in the stress-related metabolic pathway, the key interacting proteins NuoB, NuoF, CysD, ZnuC and RplX were screened, and their interaction with GroEL was verified in vivo by co-immunoprecipitation (CoIP). Finally, the linear and fast boost mode could reduce the defense capacity of E. coli O157:H7 cells against HHP stress, which is not conducive to the survival of E. coli O157:H7 under HHP, resulting in the best bactericidal effect.