Background: Variability in the health effects of dietary fiber might arise from inter-individual differences in the gut microbiota’s ability to ferment these substrates into beneficial metabolites. Our understanding of what drives this individuality is vastly incomplete and will require an ecological perspective as microbiomes function as complex inter-connected communities. Here, we performed a parallel two-arm, exploratory randomized controlled trial in 31 adults with overweight and class-I obesity to characterize the effects of long-chain, complex arabinoxylan (n= 15) at high supplementation doses (female: 25 g/day; male: 35 g/day) on gut microbiota composition and short-chain fatty acid production as compared to microcrystalline cellulose (n= 16, non-fermentable control), and integrated the findings using an ecological framework.Results: Arabinoxylan resulted in a global shift in fecal bacterial community composition, reduced α-diversity, and the promotion of specific taxa, including operational taxonomic units related toBifidobacterium longum,Blautia obeum, andPrevotella copri. Arabinoxylan further increased fecal propionate concentrations (p= 0.012, Friedman’s test), an effect that showed two distinct groupings of temporal responses in participants. The two groups showed differences in compositional shifts of the microbiota (p≤ 0.025, PERMANOVA), and multiple linear regression (MLR) analyses revealed that the propionate response was predictable through shifts and, to a lesser degree, baseline composition of the microbiota. Principal components (PCs) derived from community data were better predictors in MLR models as compared to single taxa, indicating that arabinoxylan fermentation is the result of multi-species interactions within microbiomes.Conclusion: This study showed that long-chain arabinoxylan modulates both microbiota composition and the output of health-relevant SCFAs, providing information for a more targeted application of this fiber. Variation in propionate production was linked to both compositional shifts and baseline composition, with PCs derived from shifts of the global microbial community showing the strongest associations. These findings constitute a proof-of-concept for the merit of an ecological framework that considers features of the wider gut microbial community for the prediction of metabolic outcomes of dietary fiber fermentation. This provides a basis to personalize the use of dietary fiber in nutritional application and to stratify human populations by relevant gut microbiota features to account for the inconsistent health effects in human intervention studies.Trial registration: Clinicaltrials.gov,NCT02322112, registered on July 3, 2015.

Deoxynivalenol (DON) is a mycotoxin that contaminates grains and feed. Degradation and toxicity reduction of DON by probiotics benefit human and animal health. Lactobacillus rhamnosus is an FDA-approved probiotic that can be used in children. After screening seven L. rhamnosus strains isolated from human milk, SHA113 showed the highest DON degradation rate of 60% under the optimal conditions of 37 °C, pH 6.0, OD₆₀₀ = 1.5, 5 mg L⁻¹ DON, and 48 h. When dead and live SHA113 cells were used separately, only the live cells reduced the DON concentration and transformed it into 3-epi-DON. Mice feeding experiments showed that pretreatment with SHA113 for 48 h reduced the toxicity of DON to the immunological system and organs. Directly feeding SHA113 cells could also slightly reduce the DON toxicity. Both in vitro and in vivo experiments indicated that L. rhamnosus has potential to reduce DON toxicity.

Antimicrobial peptides represent an emerging category of therapeutic agents with remarkable structural and functional diversity. Modified vasoactive intestinal peptide (VIP) (VIP analogue 8 with amino acid sequence “FTANYTRLRRQLAVRRYLAAILGRR”) without haemolytic activity and cytotoxicity displayed enhanced antimicrobial activities against Staphylococcus aureus (S. aureus) ATCC 25923 and Escherichia coli (E. coli) ATCC 25922 than parent VIP even in the presence of 180 mM NaCl or 50 mM MgCl₂, or in the range of pH 4–10. VIP analogue 8 was expressed as fusion protein thioredoxin (Trx)-VIP8 in E. coli BL21(DE) at a yield of 45.67 mg/L. The minimum inhibitory concentration (MIC) of the recombinant VIP analogue 8 against S. aureus ATCC 25923 and E. coli ATCC 25922 were 2 μM. These findings suggest that VIP analogue 8 is a promising candidate for application as a new and safe antimicrobial agent.