The study aimed to analyze the global influences of dietary inulin with different degrees of polymerization (DP) on intestinal microbial communities. Six-week-old male C57BL/6J mice were treated with fructo-oligosaccharides and inulin for 6 weeks. Fecal samples were obtained at time point 0 and 6th week. 16S rRNA sequence analysis was used to measure intestinal microbiota performed on the Illumina MiSeq platform. Influences of dietary inulin on intestinal microbiota were more complex effects than bifidogenic effects, relative abundance of butyrate-producing bacteria increased after interventions. Akkermansia muciniphila, belonging to mucin-degrading species, became a dominant species in Verrucomicrobia phylum after treatment with fructo-oligosaccharides and inulin. Modulation effects of intestinal microbiota were positively correlated with DP. Lower DP interventions exhibited better effects than higher DP treatment on stimulation of probiotics. We hypothesized that Akkermansia muciniphila played an important role on maintaining balance between mucin and short chain fatty acids.

Gut microbiota have strong connections with health. Lactulose has been shown to regulate gut microbiota and benefit host health. In this study, the effect of short-term (3 week) intervention of lactulose on gut microbiota was investigated. Gut microbiota were detected from mouse feces by 16S rRNA high-throughput sequencing, and short chain fatty acids (SCFAs) were detected by gas chromatography-mass spectrometry (GC-MS). Lactulose intervention enhanced the α-diversity of the gut microbiota; increased the abundance of hydrogen-producing bacteria Prevotellaceae and Rikenellaceae, probiotics Bifidobacteriaceae and Lactobacillaceae, and mucindegrading bacteria Akkermansia and Helicobacter; decreased the abundance of harmful bacteria Desulfovibrionaceae and branched-chain SCFAs (BCFAs). These results suggest that lactulose intervention effectively increased the diversity and improved the structure of the intestinal microbiota, which may be beneficial for host health. K E Y W O R D S16S rRNA high-throughput sequencing, gut microbiota, prebiotic, probiotics, short chain fatty acids 2 of 8 | ZHAI et Al. enzymes in the intestine, but is metabolized by gut microbiota to short chain fatty acids (SCFAs) in the ileum (Guerra-Ordaz et al., 2014).Lactulose can change the composition of the gut microbiota. For example, Vanhoutte et al. (2006), reported a significant increase in Bifidobacterium adolescentis following lactulose intake. Tuohy et al. (2002) showed that Bifidobacterium spp. were increased, whereas Clostridia and Lactobacilli were decreased after lactulose treatment in humans.SCFAs are main metabolites of gut microbiota, and are divided into straight-chain SCFAs and branched-chain SCFAs (BCFAs). Straightchain SCFAs are mainly produced by microbial fermentation of unabsorbed dietary carbohydrates in the gut. Lactate and succinate can also be metabolized to straight-chain SCFAs, including acetate, propionate, and butyrate (Hasebe et al., 2016;Verbeke et al., 2015). Straight-chain SCFAs have a range of beneficial effects, including regulation of the colonic and intracellular environment (Wong et al. 2006), and modulation of cell proliferation and gene expression. In addition, straightchain SCFAs are able to improve immune function, glucose regulation, and prevent obesity (Polyviou et al., 2016). In contrast, BCFAs are always derived from catabolism of branched-chain amino acids (Zheng et al., 2013), and are major markers of protein fermentation, which is likely to be detrimental to the host (Yang & Rose, 2015).Although some studies have assessed the effects of lactulose on gut microbiota, the gel-or PCR-based methods used limit our ability to evaluate the full extent of the impact of lactulose on the gut microbiotic community. In this study, 16S rRNA high-throughput sequencing and gas chromatography-mass spectrometry (GC-MS) were used to evaluate effect of lactulose on gut microbiota and their metabolites in mice. | MATERIAL S AND ME THODS | Animals and experiment designSix-week-old male C57BL/6J mice were...

Butyrate, a key metabolite fermented by gut microbiota mainly from undigested carbohydrates such as dietary fibers is widely used as feed additive. However, mechanisms of its contributions in maintaining host health are relatively poorly revealed. The aim of this study was to investigate how butyrate impacts gut microbiota and immunity response in high-fat diet-fed mice. Gut microbial analysis exhibited that butyrate intervention increased SCFAs-producing bacteria and decreased pathogenic bacteria, such as endotoxin-secreting bacteria. Our result also demonstrated that butyrate intervention enhanced fecal SCFAs concentrations, and inhibited endotoxin levels in feces and serum. Correlation analysis indicated positive relation between endotoxin level and Desulfovibrionaceae abundance. Furthermore, butyrate intervention inhibited expressions of IL-1β, IL-6 and MCP1/CCL2 in liver, as well as TLR4 in adipose tissue. Apart from inhibiting expressions of proinflammatory cytokines, butyrate exerted anti-inflammation effect through selectively modulating gut microbiota, such as increasing SCFAs-producing bacteria and decreasing endotoxin-secreting bacteria, as well as via regulating levels of microbiota-dependent metabolites and components, such as SCFAs and endotoxin.