Hao Ding

New therapeutic targets for noncognitive reductions in energy intake, absorption, or storage are crucial given the worldwide epidemic of obesity. The gut microbial community (microbiota) is essential for processing dietary polysaccharides. We found that conventionalization of adult germ-free (GF) C57BL/6 mice with a normal microbiota harvested from the distal intestine (cecum) of conventionally raised animals produces a 60% increase in body fat content and insulin resistance within 14 days despite reduced food intake. Studies of GF and conventionalized mice revealed that the microbiota promotes absorption of monosaccharides from the gut lumen, with resulting induction of de novo hepatic lipogenesis. Fasting-induced adipocyte factor (Fiaf), a member of the angiopoietin-like family of proteins, is selectively suppressed in the intestinal epithelium of normal mice by conventionalization. Analysis of GF and conventionalized, normal and Fiaf knockout mice established that Fiaf is a circulating lipoprotein lipase inhibitor and that its suppression is essential for the microbiota-induced deposition of triglycerides in adipocytes. Studies of Rag1-/- animals indicate that these host responses do not require mature lymphocytes. Our findings suggest that the gut microbiota is an important environmental factor that affects energy harvest from the diet and energy storage in the host. Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accession nos. AY 667702--AY 668946).

The present study was conducted to investigate the effects of dietary supplementation with Bacillus subtilis (BS) and xylo-oligosaccharides (XOS) on growth performance, intestinal morphology, intestinal microbial community, and metabolites of weaned piglets. One hundred and twenty-eight piglets were randomly allocated to one of four groups, including a control group (basal diet), BS group (basal diet + 500 g t-1 BS), XOS group (basal diet + 250 g t-1 XOS), and BS + XOS group (basal diet + 500 g t-1 BS + 250 g t-1 XOS). Dietary BS and XOS were mixed with the basal diet. All groups had eight replicates with four piglets per replicate. The experiment lasted for 42 days. The results showed that dietary XOS supplementation increased the ADFI and ADG, while decreasing the F/G. Dietary BS or XOS supplementation improved the intestinal morphology of weaned piglets by increasing the villus height and the ratio of villus height to crypt depth in the ileum. In addition, dietary XOS supplementation increased the concentrations of butyrate in the ileum and tryptamine and spermidine in the colon, while decreasing the concentration of indole in the colon compared with the control group. Dietary BS supplementation increased the colonic concentrations of butyrate, tryptamine, and cadaverine, while decreasing the concentration of skatole compared with the control group. The LEfSe analysis identified 16 biomarkers in the ileum of the BS group. The intestinal microbiota alterations of weaned piglets indicated that dietary BS or XOS supplementation could improve intestinal health by increasing the gut microbial diversity and altering the relative abundances of different bacterial species. Moreover, Spearman's correlation analysis revealed the potential link between gut microbiota alterations and metabolite changes of weaned piglets. These findings suggest that dietary XOS supplementation could alone improve the growth performance, while dietary BS or XOS and BS with XOS supplementation could influence intestinal health by altering the intestinal morphology, microbial community, and metabolites of weaned piglets. Meanwhile, there were interactions between BS and XOS in intestinal metabolites.

This study explored the effect of dietary xylo-oligosaccharide (XOS) supplementation on the gut microbial composition and activity in pigs of different ages. Eighty pigs with an average body weight (BW) of 30 kg were randomly divided into eight groups: A control group, a group that received antibiotic treatment, and six groups fed diets supplemented with 100, 250, and 500 g/t XOS, of which three groups were in the growing period (GP, 30-65 kg BW) and three groups in the growing and fattening period (GFP, 30-100 kg BW). At the end of the experiment, the intestinal contents were sampled for analyses of gut microbiota and bacterial metabolites including short-chain fatty acids (SCFAs) and bioamines. The results showed that 100 g/t XOS supplementation during the GFP significantly reduced the relative abundances of presumably pathogenic bacteria (Proteobacteria and Citrobacter), but enhanced the relative abundances of likely beneficial bacteria (Firmicutes and Lactobacillus). However, XOS supplementation during the GP showed little effect on the gut microbiota when pigs were killed at 100 kg BW. Meanwhile, 100 g/t XOS supplementation during the GFP decreased the level of 1,7-heptane diamine and increased the acetic acid, straight-chain fatty acids, and total SCFAs concentrations in the intestinal contents. Statistical analysis showed that both the dose and exposure time to XOS supplementation affected the microbial communities. In summary, 100 g/t XOS supplementation during the GFP modified the gut microbiota composition and metabolic activity. Possible consequences of such changes for the host are discussed.

To identify metabolic biomarkers related to the freshness of chilled chicken, ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) was used to obtain profiles of the metabolites present in chilled chicken stored for different lengths of time. Random forest regression analysis and stepwise multiple linear regression were used to identify key metabolic biomarkers related to the freshness of chilled chicken. A total of 265 differential metabolites were identified during storage of chilled chicken. Of these various metabolites, 37 were selected as potential biomarkers by random forest regression analysis. Receiver operating characteristic (ROC) curve analysis indicated that the biomarkers identified using random forest regression analysis showed a strong correlation with the freshness of chilled chicken. Subsequently, stepwise multiple linear regression analysis based on the biomarkers identified by using random forest regression analysis identified indole-3-carboxaldehyde, uridine monophosphate, s-phenylmercapturic acid, gluconic acid, tyramine, and Serylphenylalanine as key metabolic biomarkers. In conclusion, our study characterized the metabolic profiles of chilled chicken stored for different lengths of time and identified six key metabolic biomarkers related to the freshness of chilled chicken. These findings can contribute to a better understanding of the changes in the metabolic profiles of chilled chicken during storage and provide a basis for the further development of novel detection methods for the freshness of chilled chicken.