Working Group 1

Working Group 1 (WG1)
Working Groups

Working Group 1: Integration of fundamental knowledge on impacts of low pH on micro-organisms and identification of knowledge and technical gaps


To fully understand, influence, and manipulate the ways in which micro-organisms are affected by acid, whether it is to grow, to cease growth, or to be killed, requires an understanding of the categories of physical, chemical and biological events that result at low pH, and how the organism meets or fails to meet them. Comparative studies that list these challenges and evaluate what is known about how responses of different micro-organisms, particularly for organisms with important applications (industrial organisms, food spoilage organisms, pathogens), are very rare.

This WG will integrate studies on different organisms in a holistic fashion across different categories. This information, made available via open access, will be a unique resource. It will flag up the areas where experimental detail is lacking or in conflict, and where methodological advances are required, stimulating further collaboration in ways that will benefit the applied topics.


To produce comprehensive, comparative, and fully referenced, descriptions of the key physical and biological changes that have been determined to occur in a group of model organisms upon acid exposure, and to identify and tackle knowledge gaps and areas where data from different sources may conflict. Organisms chosen will be ones that are well characterised and have specific properties, uses, or importance (e.g., resistance to low pH, pathogenesis, industrial application).

These will include Escherichia coli (the best characterised organism, which has several inducible acid- resistance systems7), Helicobacter pylori (a well-studied acid resistant stomach pathogen8), Brucella spp. (causative agent of Brucellosis, a world-wide zoonosis, with inducible acid tolerance9), Lactobacillus spp. (acid tolerant, causes food spoilage but also used in some fermented foods10), Saccharomyces cerevisiae (the well-studied bakers and brewers years11), Candida albicans (a well- studied yeast pathogen able to tolerate a wide pH range for growth12), and Kluyveromyces marxianus, an acid tolerant yeast with multiple industrial uses13.