Salmonella enterica: A hidden risk for dry-cured meat consumption?

Abstract

Meat curing, fermentation, and drying are both preservation technologies, and traditional manufacturing practices. Despite being considered a safe food, due to the several hurdles that prevent pathogen growth, dry-cured meat manufacturing may not ensure complete pathogen elimination. Besides, the final products are still susceptible to microbial contamination. Salmonella enterica is noteworthy among the pathogenic microorganisms that can contaminate these products. To survive hypertonic/hyperosmotic, acid, and low a_w/desiccation stresses intrinsically associated with dry-curing, Salmonella has evolved with highly sophisticated mechanisms, comprising sensors/receptors, signaling cascade systems, and enzymes/transcription factors that ensure their tolerance and survival despite many harsh environmental conditions. Links between osmotic and acid stresses, such as the dissociable sigma factor of RNA polymerase, which regulates gene transcription, and mutual membrane receptors like the two-component system EnvZ/OmpR, which senses abiotic conditions, lead to stress cross-protection. Furthermore, virulence gene expression seems to be triggered by sublethal stresses on pre-adapted Salmonella cells, increasing their adherence and invasiveness of host cells. These are evidence that the ability to tolerate stresses enhances Salmonella pathogenicity and compromises the safety of dry-cured meats, by sheltering the pre-exposed and, subsequently, more virulent, stressed bacterial cells.

Keywords:

• Stress responses
• Sublethal abiotic stresses
• Virulence
• Osmotic and acid stresses
• Food safety

Acknowledgments

The authors are thankful for the financial support provided by the Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), grant number E-26/203.049/2017 and by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), grant number 311422/2016-0. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001.