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Campylobacteriosis is a zoonosis, i.e. a disease transmitted to humans by animals or animal products contaminated with a pathogenic bacterium, Campylobacter. Chicken meat is considered the main food responsible for campylobacteriosis. The control of this pathogen is a public health issue and may lead to measures envisaged from rearing to the processing of poultry products. A better understanding of the behavior of this bacterium is necessary to identify means of control. In this study, researchers from the SECALIM unit sought to examine the influence of stages in the slaughtering process on the behavior of Campylobacter jejuni. These steps, associated with soaking in hot water (scalding) and accelerated refrigeration (chilling), constitute stress for bacteria liable to induce adaptation mechanisms which may result from modifications in the expression of bacterial genes. The expression of a selection of 44 genes from 3 strains of C. jejuni was thus quantified by RT-qPCR, after the application of stresses inspired by the slaughter process. The main results indicate that the expression of 26 genes varied according to the successive thermal stresses applied, according to three different expression profiles according to the strains and the stress conditions. Among these genes, some overexpressed mainly corresponded to genes involved in the heat shock response, while underexpressed genes belonged to lipid and amino acid metabolism. Four genes whose overexpression was similar for the three strains could represent indicators of the heat stress response at the species level. Advances in the molecular understanding of the stress response of pathogenic bacteria, such as Campylobacter, in real process conditions will make it possible to identify technological levers in order to better control the microbial risk and thus reduce the incidence of campylobacteriosis.
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This study was performed by UMR INRAE-Oniris SECALIM at Nantes in the framework of the BIOMICS supported by the West Agronomic Pole recently integrated into Valorial, with financial support from the Brittany and Pays de la Loire regions.

Associated publication:

Duqué B, Rezé S, Rossero A, Membré J-M, Guillou S, Haddad N. Quantification of Campylobacter jejuni gene expression after successive stresses mimicking poultry slaughtering steps. Food Microbiol. 2021 https://doi.org/10.1016/j.fm.2021.103795