Veillonella faecalis sp. nov., a propionic acid-producing bacterium isolated from the faeces of an infant.

A strictly anaerobic, Gram-stain-negative, catalase-negative, cocci-shaped, and propionate-producing bacterial strain, named Ds1651T was isolated from the fecal sample collected from a South Korean infant. Through a comparison of 16S rRNA gene sequences, it was revealed that Ds1651T had the highest phylogenetic affinity with Veillonella nakazawae KCTC 25297 T (99.86%), followed by Veillonella infantium KCTC 25370 T (99.80%), and Veillonella dispar KCTC 25309 T (99.73%) in the family Veillonellaceae. Average nucleotide identity values between Ds1651T and three reference species were 95.48% for Veillonella nakazawae KCTC 25297 T, 94.46% for Veillonella infantium KCTC 25370 T, and 92.81% for Veillonella dispar KCTC 25309 T. The G + C content of Ds1651T was 38.58 mol%. Major fermentation end-products were acetic and propionic acids in Trypticase peptone glucose yeast extract broth with 1% (v/v) sodium lactate. The predominant cellular fatty acids that account for more than 10% were summed in Feature 8 (C17:1 ω8c and/or C17:2) and C13:0. Based on the findings from phylogenetic, genomic, phenotypic, and chemotaxonomic studies, we propose that the type strain Ds1651T (= KCTC 25477 T = GDMCC 1.3707 T) represents a novel bacterial species within the genus Veillonella, with the proposed name Veillonella faecalis sp. nov.

Limosilactobacillus reuteri DS0384 promotes intestinal epithelial maturation via the postbiotic effect in human intestinal organoids and infant mice.

Little is known about the modulatory capacity of the microbiota in early intestinal development. We examined various intestinal models that respond to gut microbial metabolites based on human pluripotent stem cell-derived human intestinal organoids (hIOs): physiologically relevant in vitro fetal-like intestine, intestinal stem cell, and intestinal disease models. We found that a newly isolated Limosilactobacillus reuteri strain DS0384 accelerated maturation of the fetal intestine using 3D hIO with immature fetal characteristics. Comparative metabolomic profiling analysis revealed that the secreted metabolite N-carbamyl glutamic acid (NCG) is involved in the beneficial effect of DS0384 cell-free supernatants on the intestinal maturation of hIOs. Experiments in an intestinal stem cell spheroid model and hIO-based intestinal inflamed model revealed that the cell-free supernatant from DS0384 comprising NCG promoted intestinal stem cell proliferation and was important for intestinal protection against cytokine-induced intestinal epithelial injury. The probiotic properties of DS0384 were also evaluated, including acid and bile tolerance and ability to adhere to human intestinal cells. Seven-day oral administration of DS0384 and cell-free supernatant promoted the intestinal development of newborn mice. Moreover, NCG exerted a protective effect on experimental colitis in mice. These results suggest that DS0384 is a useful agent for probiotic applications and therapeutic treatment for disorders of early gut development and for preventing intestinal barrier dysfunction.