Progetto PSR (2025) Linea 8-Sottomisura B- Dott.ssa Simona PIZZI (Tutor: Prof. Mora Diego) - Missione a Monaco di Baviera

Helicobacter pylori is a pathogenic microorganism affecting approximately 50% of the world population, causing chronic gastritis and adenocarcinoma. The increasing ability of strains to develop antibiotic resistance is a significant problem that has reduced the effectiveness of standard therapies, making it necessary to explore alternative strategies such as the use of probiotic strains to counteract H. pylori gastric colonization (Westphal et al., 2015). This project aims to evaluate the effect of the urease-positive S. thermophilus DSM 20617T (Mora et al., 2004) and the derivative mutants’ A16 and ES3 (Arioli at el., 2024) respectively urease-negative by a knockout of the ureC gene and with increased urease activity due to a mutation introduced in the accessory gene ureE, on the survival and growth of H. pylori. These experiments will be carried out at the Department of Medicine II, University Hospital, LMU, Munich, Germany, under the supervision of Dr. Christian Schulz and Dr. Nadine Koch. To this end, the following methodological approaches will be adopted: 1.Plate assay (agar spot or overlay) to determine the direct inhibition of H. pylori growth in the presence of the different bacterial variants, based on established protocols. 2.Transwell system to study the indirect effect of metabolites produced by the tested strains, with particular focus on microenvironment modulation through the diffusion of active substances. 3.Kinetic growth monitoring by measuring optical density (OD), in order to analyse the growth effects of H. pylori and bacterial strains in co-culture. 4.Evaluation of urease activity and pH modulation through phenol red assay, to correlate the ability of strains to alter environmental pH with their impact on H. pylori. This combination of methodologies will allow an integrated characterization of both direct effects and those mediated by urease activity, providing essential data for the development of innovative probiotic strategies.