Genome Analysis of Enterococcus mundtii Pe103, a Human Gut-Originated Pectinolytic Bacterium.

Pectin exists in significant amounts in vegetables and fruits as a component of the plant cell wall. In human diet, pectin is not degraded by the human digestive enzymes due to its complex structure; only gut bacteria degrade pectin in the large intestine. To date, although pectin is one of the most important sources of dietary fiber in human diet, there have been only few reports on human gut-originated pectinolytic bacteria. In this study, the strain Enterococcus mundtii Pe103, a bacterium with pectin-degrading activity, was isolated from the feces of a healthy Korean adult female. Culture experiments revealed that it could grow on pectin as the sole carbon source by degrading pectin to approximately 35% within 13 h. We report the complete genome data of human gut E. mundtii Pe103. It consists of a circular chromosome (3,084,146 bps) and two plasmids (63,713 and 56,223 bps). Genomic analysis suggested that at least nine putative enzymes related to pectin degradation are present in E. mundtii Pe103. These enzymes may be involved in the degradation of pectin. The whole genome information of E. mundtii Pe103 could improve the understanding of the mechanism underlying the degradation of pectin by human gut microbiota.

Enrichment of Polyglucosylated Isoflavones from Soybean Isoflavone Aglycones Using Optimized Amylosucrase Transglycosylation.

Isoflavones in soybeans are well-known phytoestrogens. Soy isoflavones present in conjugated forms are converted to aglycone forms during processing and storage. Isoflavone aglycones (IFAs) of soybeans in human diets have poor solubility in water, resulting in low bioavailability and bioactivity. Enzyme-mediated glycosylation is an efficient and environmentally friendly way to modify the physicochemical properties of soy IFAs. In this study, we determined the optimal reaction conditions for Deinococcus geothermalis amylosucrase-mediated α-1,4 glycosylation of IFA-rich soybean extract to improve the bioaccessibility of IFAs. The conversion yields of soy IFAs were in decreasing order as follows: genistein > daidzein > glycitein. An enzyme quantity of 5 U and donor:acceptor ratios of 1000:1 (glycitein) and 400:1 (daidzein and genistein) resulted in high conversion yield (average 95.7%). These optimal reaction conditions for transglycosylation can be used to obtain transglycosylated IFA-rich functional ingredients from soybeans.

Effect of raw potato starch on the gut microbiome and metabolome in mice.

The gut microbiome plays a pivotal role in human health and is affected by various factors. To investigate the association between phenotypic and microbiota-related changes in the gut and a raw starch-based diet, we fed mice with different starch substitutes (corn, wheat, rice, and potato) for 16 weeks. The potato starch-fed group showed the lowest weight gain and fat tissue accumulation of all the groups, as well as the highest insulin sensitivity. Taxonomic analysis indicated that the proportions of Akkermansia, Rikenellaceae, and Sutterella showed the greatest increase in the ceca of mice fed raw potato starch. In addition, the gut microbiota of the raw potato starch group showed the highest carbohydrate and energy metabolism of all the groups, as confirmed by cecal metabolite analysis. The raw potato starch group also produced the highest propionic acid content. Our results showed that the differences in the digestibility of each starch, differences in the phenotype in terms of digestibility, and changes in intestinal microbiota were connected, and it was confirmed that potato starch, which had the lowest digestibility, caused the greatest difference in intestinal microbe composition and metabolism.

Effects of raw potato starch on body weight with controlled glucose delivery.

Starch digestion in the gastrointestinal tract has different properties depending on its botanical source. In this study, corn, wheat, rice, and potato starches were used to test the digestion properties of mammalian mucosal α-glucosidase in an in vitro assay, and their physiological effects were investigated in male C57BL/6 mice. The results clearly demonstrated that potato starch caused the lowest rates of glucose generation, suggesting that it can attenuate the postprandial glucose spike. Interestingly, a potato starch-based diet caused significantly (P < 0.05) lower weight gain and fat accumulation compared to diets based on other starches, through increased insulin sensitivity. This result suggests that potato starch-based products can be used to regulate postprandial blood glucose levels, aiding in the control of metabolic diseases.