Everybody loves cheese: crosslink between persistence and virulence of Shiga-toxin Escherichia coli

Abstract

General cheese manufacturing involves high temperatures, fermentation and ripening steps that function as hurdles to microbial growth. On the other hand, the application of several different formulations and manufacturing techniques may create a bacterial protective environment. In cheese, the persistent behavior of Shiga toxin-producing Escherichia coli (STEC) relies on complex mechanisms that enable bacteria to respond to stressful conditions found in cheese matrix. In this review, we discuss how STEC manages to survive to high and low temperatures, hyperosmotic conditions, exposure to weak organic acids, and pH decreasing related to cheese manufacturing, the cheese matrix itself and storage. Moreover, we discuss how these stress responses interact with each other by enhancing adaptation and consequently, the persistence of STEC in cheese. Further, we show how virulence genes eae and tir are affected by stress response mechanisms, increasing either cell adherence or virulence factors production, which leads to a selection of more resistant and virulent pathogens in the cheese industry, leading to a public health issue.

Keywords:

• Acid stress
• cross protection
• heat shock
• osmotic stress
• STEC
• stress responses

Acknowledgment

The authors would like to thank the Conselho Nacional de Desenvolvimento Científico e Tecnológico (process no. 405728/2018-2 and 402430/2018-2, CNPq, Brazil).

Additional information

Funding

This study was financed in part by the Fundação de Amparo à Pesquisa do Estado da Bahia (FAPESB), grant number BOL0439-2019.