17th Acidic Friday

17th Acidic Friday
Date: 20.01.2023 15:00 CET
Venue: Zoom
Location: Online

Open discussion platform of the COST action EuroMicropH. This discussion series is intended to stimulate an exchange on the different aspects of how microorganisms react to low pH conditions and why people are interested to investigate this subject. 

Please register here.

20.01.2023 15:00 CET


Meeting-ID: 978 6401 0941
Passwort: b4mbwdXK


15:00 Wellcome by the discussion leaders Arícia Possas and Conor O´Byrne

15:05 Linda Kenney, University of Texas Medical Branch, USA

The role of acid stress in Salmonella pathogenesis

15:30 Melina Kitsiou, University of Surrey, United Kingdom

The role of the acid stress response of the pathogen Listeria monocytogenes to novel sustainable processing technologies


The role of acid stress in Salmonella pathogenesis

Linda Kenney

I will describe how the acid pH of the vacuole is sensed by Salmonella, resulting in an acidic cytoplasm. The acid pH up-regulates the number of SsrA and SsrB two-component proteins. SsrB binding to DNA is also pH-sensitive and it activates transcription of genes located on Salmonella pathogenicity island 2 that enable Salmonella to survive and replicate in the vacuole. Lastly, I will demonstrate how a conserved histidine residue in the phosphorylation domain of SsrB allosterically activates the DNA binding domain to drive virulence.

The role of the acid stress response of the pathogen Listeria monocytogenes to novel sustainable processing technologies

Melina Kitsiou

The principle of the hurdle technology approach on microbial safety is the utilization of two or more methods/approaches/processes to enable microbial inactivation and consequently to ensure food safety. A combination of them could lead to synergistic and/or complementary actions against bacteria but could also provide cross protection especially when using mild decontamination methods. To develop novel hurdle technology approaches, it is important to understand the mode of action and the microbial stress response for each treatment. For example, it is known that the gene regulator, SigB, plays a major role in the environmental stress adaptation of L. monocytogenes for multiple type of environmental stresses such as acid, thermal or osmotic stress. The aim of our work is to develop novel green hurdle technology approaches, targeting the weakness of L. monocytogenes stress response. For this reason, acid stress and cold atmospheric plasma were assessed individually and/or combined.

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