Background Non-digestible fibers, or prebiotics, are frequently prescribed for their health benefits by regulating gut microbiota (probiotics). Gut microorganisms selectively ferment prebiotics, producing specific metabolite profiles. We believe gut microbial populations and their metabolic activity can be modulated through targeted manipulation of prebiotic composition. Hence, we aimed to engineer gut metabolites using different fiber blends as a versatile platform with clinically relevant bioactivities to mitigate various metabolic and inflammatory disorders.

Methods A consortium of six gut-abundant strains (Lactobacillus and Bifidobacterium) was cultivated in 1/5 diluted 200ml MRS medium with 5% of three different commercial prebiotic supplements (A, B, and C, having different fiber ingredients) and lab-produced levan from Bacillus subtilis MRS 4-4B strain. Samples, including a control without prebiotics, were incubated anaerobically at 37°C for up to 5 days. Initial and final pH levels were recorded. Secondary metabolites were extracted with ethyl acetate (1:1 ratio) post-incubation. Antimicrobial activity against E. coli was assessed using the well-diffusion method, and antioxidant activity was determined via the DPPH assay.

Results The drop in pH from neutral to 4 in all cultures was observed after growth. The ethyl acetate extracted metabolites from each sample showed very different colors and textures from their parent prebiotics, indicating the production of different metabolites with different prebiotics. Prebiotic C showed the highest antimicrobial activity with a 9mm zone of inhibition against E. coli and the highest antioxidant activity (82.5%) as compared to other prebiotic supplements. Interestingly, microbial metabolites produced with levan (fructooligosaccharides) also exhibited high biological activities (6mm inhibition zone and 82.7% antioxidant activity), demonstrating its great prebiotics promise for future uses.

Conclusions The difference in color and biological activities of metabolites in all samples indicates the probability of the presence of different secondary metabolites produced by the gut microbial consortium in the presence of different fiber supplements. Identification of metabolites by various physiochemical techniques is under progress. This work provides a robust foundation for engineering gut metabolites to modulate host-microbiome interactions and supports the use of customized prebiotics as a worthwhile strategy for personalized medicine and clinical intervention.