Bile Acid Deconjugation and Anti‐ Helicobacter pylori Activity of Limosilactobacillus reuteri DSM 34531

Limosilactobacillus reuteri DSM 34531 has been attributed with probiotic characteristics, including a reduction of symptoms of acute diarrhea and atopic dermatitis. Yet, other probiotic features typical for some Lm. reuteri strains such as bile salt hydrolase (BSH) and anti- Helicobacter pylori activity have hitherto not been documented. Whole genome sequencing of Lm. reuteri DSM 34531 was performed to identify BSH genes, followed by BSH classification into previously described BSH clades. Suspended cell pellets and supernatants were tested for BSH activity via a quantitative colorimetric method. Auto- and co-aggregation, and urease activity of single and mixed Lm. reuteri DSM 34531 and H. pylori DSM 21031T cultures were evaluated using optical density- and microscopy-based approaches. Genome analysis of Lm. reuteri DSM 34531 revealed a single BSH-encoding gene, with its protein sequence clustering closest to the BSH-T3 phylotype. Corresponding in vitro BSH activity was confirmed. Lm. reuteri DSM 34531 co-aggregated with H. pylori DSM 21031T and reduced its urease activity. Conclusively, our data suggest that Lm. reuteri DSM 34531 possesses an active BSH, suggesting potential relevance to cholesterol metabolism. We also demonstrate in vitro co-aggregation with H. pylori while reducing its urease activity indicating potential anti-H. pylori activity under in vitro conditions.