Genome-guided prebiotic fermentation generates anti-virulence metabolites against Pseudomonas aeruginosa

The rise of multidrug-resistant Pseudomonas aeruginosa has heightened interest in microbiome-based anti-virulence strategies that mitigate pathogenicity without directly affecting bacterial survival. This study examined whether the fermentation of Arabic gum and baobab by probiotic bacteria produces metabolites that reduce P. aeruginosa virulence.

The carbohydrate-active enzyme profiles of Bifidobacterium longum, Lactiplantibacillus plantarum, and P. aeruginosa were compared to predict their ability to utilize plant glycans. Probiotic growth, viable counts, and acidification were measured following supplementation with Arabic gum, baobab, or glucose. The effects of untreated, neutralized, and pH-matched cell-free supernatants on P. aeruginosa growth, biofilm formation, adhesion, and twitching motility were evaluated.

L. plantarum and B. longum exhibited 54 and 53 glycoside hydrolases, respectively, compared to 29 in P. aeruginosa, suggesting a superior probiotic capacity for plant-glycan utilization. Arabic gum at 2% significantly enhanced B. longum viability by approximately 0.27 log₁₀ CFU mL^-1 (P = 0.0058) and resulted in the greatest pH reduction, whereas glucose increased L. plantarum growth by approximately 0.58 log₁₀ CFU mL^-1 (P = 0.0019). Supernatants derived from Arabic gum exhibited the strongest activity, nearly completely inhibiting biofilm formation, reducing adhesion by approximately 54%, and significantly suppressing twitching motility. Baobab demonstrated measurable but generally weaker prebiotic and anti-virulence effects. These findings indicate that the biological effects were contingent on the fermented substrate and the resulting metabolite profile. Neutralization reduced several inhibitory effects, while pH-matched controls largely replicated the growth suppression observed with the corresponding CFS. This indicates that fermentation-associated acidification was a primary determinant of antibacterial activity. The residual activity observed in certain neutralized CFS preparations suggests that additional non-acidic factors may contribute under specific conditions.

Genome-informed glycan-utilization predictions identified substrates capable of producing probiotic metabolites that attenuate multiple P. aeruginosa virulence phenotypes. Arabic gum shows particular promise for microbiome-based control of multidrug-resistant P. aeruginosa.