Probiotics are known to alleviate inflammatory bowel disease, and their precise mechanisms remain unclear. In this study, we identified a strain of Enterococcus hirae QT4713, isolated from the Tibetan plateau, that exhibited high anti-inflammatory activity in vitro. After confirming its tolerance to gastrointestinal fluids and safety, we evaluated the effect of E. hirae QT4713 on IBD using a dextran sulfate sodium (DSS)-induced colitis mouse model and analyzed the microbial response through metagenomic and metabolomics. The results indicated that E. hirae QT4713 alleviated colitis symptoms by reducing oxidative stress in the serum and inflammatory cytokine levels in colonic tissue, particularly IL-1β (P < 0.05). It also reduced structural damage, inflammatory infiltration, and epithelial cell apoptosis in the colon. Additionally, the strain increased the expression of MUC-2 and occludin in colonic tissue, which helped to protect the colonic barrier. Furthermore, intervention with E. hirae QT4713 enriched beneficial bacteria such as Bifidobacteria and Lactobacillus, increased the levels of butyric acid and propionic acid in the gut (P < 0.05), regulated tryptophan metabolism, and promoted the production of its indole derivatives, including 3-indoleacetonitrile, 3-indoleacrylic acid, and indole-3-lactic acid (P < 0.05), thus alleviating colitis. These findings provide new insights into how probiotics, such as E. hirae QT4713, alleviated colitis in a gut microbiota/tryptophan metabolism-dependent manner.

Black wolfberry (Lycium ruthenicum) is enriched in phytochemical metabolites which can benefit human health. However, few studies have examined the effects of different fruit drying methods on its polyphenol content, antioxidant activity, and anti-inflammatory activity. In addition, whether and how consuming dried black wolfberry affects gut microbiota has not been reported. This study assessed the phytochemical profile and bioactivities of black wolfberry dried through different methods, and subsequently characterized changes in human fecal microbiota associated with freeze-dried black wolfberry in vitro. The results showed that freeze-dried samples retained higher total phenolics ((49.68 ± 1.62) mg GAE/g DM), tannins ((38.64 ± 1.35) mg GAE/g DM), and proanthocyanidins ((3.35 ± 0.30) mg/g DM) compared to sun drying or hot air drying (P < 0.05), and exhibited higher antioxidant and anti-inflammatory activities. In human fecal inoculum bioreactor fermentations, freeze-dried black wolfberry was associated with increased species richness and α-diversity. At the genus level, fermentations treated with black wolfberry had a higher abundance of lactic acid bacteria including Lactococcus, Bifidobacterium, Lactobacillus, Pediococcus, and Weissella, as well as butyrate-producing bacteria compared to the untreated samples, suggesting enrichment for taxa associated with a healthy gut microbiome. In addition, the black wolfberry treatment group had higher levels of short-chain fatty acids, which were consistent with PICRUSt2 inference. This study defines an optimal method for black wolfberry preservation to retain the beneficial compounds, and provides a foundation for further exploration of its potential benefits for human gut microbiota.