7th Acidic Friday

7th Acidic Friday
Date: 18.06.2021
Venue: Zoom
Location: Zoom

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 for the upcoming meeting. To access the meeting please follow the Zoom link beneath.

18.06.2021 16:00 CEST

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Michael Sauer, BOKU University, Vienna, Austria

Conor O’Byrne, NUI Galway, Ireland


16:00 Welcome

Change in Programm

16:05 Petra Louis, The Rowett Institute, University of Aberdeen, United Kingdom

Influence of colonic pH on microbial ecology of dietary fibre fermentation

16:25 Update on publishing with FEMS, John Morrissey, University College Cork, Ireland

The talk of Pooja Jayaprakash will be shifted to an Acidic Friday in autumn 2021.

(Pooja Jayaprakash, University of Milano Bicocca, Italy, Contribution of PDR12 to weak organic acids resistance in the yeast Zygosaccharomyces parabailii)


Influence of colonic pH on microbial ecology of dietary fibre fermentation, Petra Louis

The food borne Listeria monocytogenes is a gram-positive bacterium capable of surviving the low pH imposed by the gastrointestinal (GI) tract and invade the human body. The alternative sigma factor B (σB) is responsible for L. monocytogenes stress resistance by upregulating approximately 300 genes, many of which encode protective and homeostatic functions to counteract environmental changes. σB is controlled by a signal cascade, which in turn is activated by a multi-protein complex designated as the stressosome. In this study, we constructed several mutations in the stressosome, which resulted in either its inactivation or over activation. We also determinate that the stressosome is responsible for the triggering of σB at mild acidic conditions (pH 5), resulting in the upregulation of the σB regulon, virulence factors and increased resistance towards lethal acidic stress (pH 2.5). Our results help shed light on the molecular mechanism of the signal transduction that lead to the activation of the general stress response in L. monocytogenes.

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