Limosilactobacillus fermentum K73 synbiotic modulates gut microbiota function and behavior in gnotobiotic mice transplanted with microbiota from children diagnosed with autism spectrum disorder

Dietary interventions targeting gut dysbiosis are gaining attention as potential therapeutic strategies for several pathological conditions. We previously demonstrated that an encapsulated synbiotic containing Limosilactobacillus fermentum K73 modulates human gut microbiota in vitro . Here, we extended this work using gnotobiotic mice colonized with gut microbiota from Colombian children diagnosed with autism spectrum disorder (ASD) or neurotypical (NT) donors. 16S rRNA sequencing showed that ASD- and NT-derived microbiota differed in both richness and composition, and humanized mice retained key features of their corresponding donor microbiota. Synbiotic supplementation significantly increased beneficial taxa abundance and short-chain fatty acid production, with more pronounced effects observed in ASD-colonized mice. These metabolic shifts were accompanied by behavioral improvements, including increased sociability and marble-burying performance, consistent with beneficial microbiota modulation. Together, these findings support synbiotic supplementation as a viable strategy to modulate dysbiotic gut microbiomes. Importantly, our results expand microbiome knowledge to understudied Latin American populations.