A Novel Grape-Derived Prebiotic Selectively Enhances Abundance and Metabolic Activity of Butyrate-Producing Bacteria in Faecal Samples

Detection of indigenous gut bacteria related to red chilli pepper (Capsicum annuum) in murine caecum and human faecal cultures

BACKGROUND

Red chilli pepper (Capsicum annuum; RP) is a popular spice containing the active compound capsaicin. Indigenous gut bacteria and metabolism can affect host health. The functions of capsaicin, including the regulation of metabolic health and anti-oxidant properties, may be correlated with the gut microbiota.

METHODS

To identify indigenous gut bacteria that are responsive to RP, Institute of Cancer Research mice fed a diet with no fibre or with 5% (w/w) RP for 14 days. Additionally, human stool samples collected from four healthy volunteers were incubated without (control) or with 2% (w/v) RP at 37 °C for 24 h. Microbiota in murine caecal samples and human faecal cultures were analysed using 16S rRNA (V4) amplicon sequencing.

RESULTS

Compared with the microbiota in mice fed no-fibre diets, Lachnospiraceae spp.-, Muribaculaceae spp.-, and Phacaeicola vulgatus-like bacteria were defined as murine RP-responsive indigenous gut bacteria (RP-RIB). In the human faecal cultures, acetate and propionate levels were higher in RP cultures than in the control cultures. Subdoligranulum spp.-, Blautia spp.-, Faecalibacterium prausnitzii-, P. vulgatus-, and Prevotella copri-like bacteria were defined as human RP-RIB. Compared with control culture Fe-reducing power was increased in the culture with RP.

CONCLUSION

RP increases the amount of short-chain fatty acid-producing bacteria and beneficial gut bacteria in mouse and human faecal cultures. Overall, RP could have a positive effect on the host by altering the gut microbiota.

Gut Microbiota and Metabolite Changes in Patients With Ulcerative Colitis and Clostridioides difficile Infection

Background

Patients with ulcerative colitis (UC) are at an increased risk of developing Clostridioides difficile infection (CDI), which in turn leads to poor outcomes. The gut microbial structure and metabolites in patients with UC and CDI have been scarcely studied. We hypothesized that CDI changes the gut microbiota and metabolites of patients with UC.

Materials and Methods

This study included 89 patients: 30 healthy controls (HC group), 29 with UC alone (UCN group), and 30 with UC and CDI (UCP group). None of the participants has been exposed to antibiotic treatments during the 3 months before stool collection. Stool samples were analyzed using 16S rRNA gene sequencing of the V3–V4 region and gas chromatography tandem time-of-flight mass spectrometry.

Results

The UCN group displayed lower diversity and richness in gut microbiota and a higher relative abundance of the phylum Proteobacteria than the HC group. There were no significant differences between the UCN and UCP groups in the α-diversity indices. The UCP group contained a higher relative abundance of the genera Clostridium sensu stricto, Clostridium XI, Aggregatibacter, and Haemophilus, and a lower relative abundance of genera Clostridium XIVb and Citrobacter than the UCN group. In the UCP group, the increased metabolites included putrescine, maltose, 4-hydroxybenzoic acid, 4-hydroxybutyrate, and aminomalonic acid. Spearman’s correlation analysis revealed that these increased metabolites negatively correlated with Clostridium XlVb and positively correlated with the four enriched genera. However, the correlations between hemoglobin and metabolites were contrary to the correlations between erythrocyte sedimentation rate and high-sensitivity C-reactive protein and metabolites.

Conclusion

Our study identified 11 differential genera and 16 perturbed metabolites in patients with UC and CDI compared to those with UC alone. These findings may guide the design of research on potential mechanisms and specific treatments for CDI in patients with UC.

Progress in understanding of relationship between short chain fatty acids and irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional intestinal disease whose pathogenesis has not yet been fully defined. The main clinical manifestations of IBS are irregular abdominal pain, abdominal distension, and changes in stool character and defecation habits. As one of the pathogeneses of IBS, intestinal flora imbalance plays an important role in the development of IBS. The vast majorities of short chain fatty acids (SCFAs) are produced through the interaction of intestinal flora with host diet in the colon. As one of the main metabolites of intestinal flora, SCFAs have the effects of intestinal barrier protection, immune regulation, anti-inflammation, and regulation of visceral sensitivity in the intestine. In recent years, with the increasing attention to SCFAs, studies on the relationship between SCFAs and IBS are emerging. This review summarizes the progress in the understanding of the relationship between SCFAs and IBS in recent five years.