Baseline microbial ecology encodes probiotic responsiveness through distinct metabolic and network configurations.

Preventive probiotic administration in inflammatory bowel disease mouse models reduces disease severity and histopathological damage only in recipients whose baseline microbiomes have higher diversity and more complex co-occurrence architecture.

• Why it matters: Probiotic efficacy varies widely across individuals with inflammatory bowel disease, but the ecological sources of that variability are poorly understood.
• What they did: Using a D-lactate–nonproducing consortium across three independent mouse resources, the study compared baseline diversity/co-occurrence, measured community structure and metabolic outputs, and tested whether sustained exogenous D-lactate abolished protection.
• The result: The consortium preserved community structure and restored disease-disrupted metabolites, selectively raising butyrate and propionate; sustained D-lactate did not abolish protection, suggesting responsiveness is encoded in baseline microbiota and is predictable before intervention.