Showing papers by "Pieter Van den Abbeele published in 2019"

A synbiotic concept containing spore-forming Bacillus strains and a prebiotic fiber blend consistently enhanced metabolic activity by modulation of the gut microbiome in vitro

Abstract: A standardized in vitro simulation of the human gastrointestinal tract (M-SHIME®) was used to assess the effect of repeated daily administration of a synbiotic formulation, containing five spore-forming Bacillus strains and a prebiotic fiber blend, on the microbial activity and composition of three simulated human subjects. Firstly, while confirming recent findings, deeper phylogenetic insight was obtained in the resident M-SHIME® microbiota, demonstrating that the model maintains a diverse and representative, colon region-specific luminal and mucosal microbial community. Supplementation of the synbiotic concept increased microbial diversity in the distal colon areas, whereas specific enhancement of Bacillaceae levels was observed in the ascending colon suggesting a successful engraftment of the Bacillus spores, which probably resulted in a stimulatory effect on, among others, Bifidobacteriaceae, Lactobacillaceae, Prevotellaceae, Tannerellaceae and Faecalibacterium prausnitzii contributing directly or indirectly to stimulation of acetate, propionate and butyrate production. When compared with a previous study investigating the Bacillus strains, the generated data suggest a synergistic effect on the intestinal microbiota for the synbiotic formulation. Given the fact that the probiotic strains have been shown to impact post-prandial metabolic endotoxemia in human individuals, it might be interesting to further investigate the efficacy of the synbiotic concept in protecting against obesity-related disorders.

Applying Advanced In Vitro Culturing Technology to Study the Human Gut Microbiota.

Abstract: The human gut microbiota plays a vital role in both human health and disease. Studying the gut microbiota using an in vivo model, is difficult due to its complex nature, and its diverse association with mammalian components. The goal of this protocol is to culture the gut microbiota in vitro, which allows for the study of the gut microbiota dynamics, without having to consider the contribution of the mammalian milieu. Using in vitro culturing technology, the physiological conditions of the gastro intestinal tract are simulated, including parameters such as pH, temperature, anaerobiosis, and transit time. The intestinal surface of the colon is simulated by adding mucin-coated carriers, creating a mucosal phase, and adding further dimension. The gut microbiota is introduced by inoculating with the human fecal material. Upon inoculation with this complex mixture of bacteria, specific microbes are enriched in the different longitudinal (ascending, transverse and descending colons) and transversal (luminal and mucosal) environments of the in vitro model. It is crucial to allow the system to reach a steady state, in which the community and the metabolites produced remain stable. The experimental results in this manuscript demonstrate how the inoculated gut microbiota community develops into a stable community over time. Once steady state is achieved, the system can be used to analyze bacterial interactions and community functions or to test the effects of any additives on the gut microbiota, such as food, food components, or pharmaceuticals.

Lactulose Crystals Beneficially Affect Community Composition Along Entire Human Colon in Vitro, Resulting in Donor-Dependent Prebiotic Effects at Metabolic Level

Abstract: A validated in vitro gut model (i.e. SHIME®) was used to assess the effect of repeated daily administration of lactulose on microbial metabolic activity and community composition in different colonic areas, with the focus on inter-individual differences among three human subjects. An initial rise in acetate and lactate levels was observed in the proximal colon after lactulose administration, which could be linked to an overall strong bifidogenic effect as well as higher Lactobacilli levels in donors 2 and 3. Particularly two operational taxonomic units (OTUs) related to Bifidobacterium adolescentis and Bifidobacterium longum increased with lactulose addition. The enhanced acetate and lactate production subsequently stimulated microbial species involved in cross-feeding interactions, resulting in the donor-dependent production of propionate and/or butyrate. Additionally, a reduction in markers of proteolytic fermentation was detected upon lactulose supplementation. A wide spectrum of propionate- and especially butyrate-producing microbes, such as the next-generation probiotics Faecalibacterium prausnitzii and Akkermansia muciniphila, were donor-dependently enhanced in the distal colon, which is of specific interest as many colonic diseases originate in the distal part of the colon. For the first time beneficial effects of lactulose on the microbiota as well as metabolic activity could be demonstrated over the entire colon in vitro.