Integrated multi-omics analysis revelas probiotic-conditioned host response induced by Streptococcus salivarius 24SMBc in Dictyostelium discoideum

Both S. salivarius and S. mutans reduced Dictyostelium growth compared to E. coli (control). However, S. salivarius significantly improved viability, particularly in sequential exposure experiments, where pre-culture with S. salivarius followed by S. mutans increased vitality by 30%. Moreover, while S. mutans reduced Dictyostelium chemotactic competence, S. salivarius enhanced it.

Pre-culture with S. salivarius also increased phagocytosis of oral pathogens (S. mutans and E. corrodens), confirmed by higher intracellular ROS. Transcriptomic and metabolomic analyses further support obtained results, indicating a more active metabolic and phagocytic-primed state after S. salivarius-exposure. In contrast, S. mutans induced a stressed, energy-depleted profile.

In conclusion, S. salivarius primed innate immune functions, enhancing Dictyostelium viability, chemotaxis and phagocytic capacity. These findings support Dictyostelium as a simple, cost-effective model for probiotic screening and pathogen-induced stress response studies.