Abstract:

In order to study the sublethal characteristic and regulation mechanism of Salmonella Typhimurium in response
to heat stress, its sublethal and growth curves under different high temperature were investigated. The cell membrane integrity
and changes of transcriptional sigma factors in sublethal Salmonella Typhimurium were analyzed using real-time PCR. Results
showed that significant injuries occurred on the outer and cytoplasmic membranes of Salmonella Typhimurium following heat
treatment at 60 ℃ and a significant damage in cell membrane integrity was also observed. The growth curve and damage in
cell membrane integrity following heat treatment at 42 ℃ was not significantly different from those of the control. This finding
might be associated with the transcriptional induction of sigma factors. The current preliminary study revealed that the sublethal
state of Salmonella Typhimurium exposed to heat stress might be the intermediate transition state in the process of inactivation,
which could be closely linked to the cell membrane integrity and key gene expression and regulation. The findings in this study
presented useful insights for the establishment of thermal processing techniques for microbiologically safe foods.

Key words: Salmonella Typhimurium；sublethal injury；heat stress；cell membrance integrity；transcriptional regulation of &sigma, factors