Obesity is associated with gut microbiota dysbiosis, characterized by a high Firmicutes/Bacteroidetes ratio. Gut-dwelling bacteria of the Christensenellaceae family have been proposed to act as keystones of the human gut ecosystem and to prevent adipogenesis. The objectives of the present study were to demonstrate the antiobesity potential of a new strain of Christensenella minuta in preclinical models and explore related mechanisms of action. The antiobesity potential of C. minuta DSM33407 was assessed in a diet-induced obesity mouse model. Changes in hepatic lipid metabolism were explored using targeted transcriptomics. Effects on gut microbiota were further assessed in a humanized Simulator of the Human Intestinal Microbial Ecosystem (SHIME^®) model inoculated with obese fecal samples. Shotgun metagenomics was applied to study microbial community structures in both models. C. minuta DSM33407 protected from diet-induced obesity and regulated associated metabolic markers such as glycemia and leptin. It also regulated hepatic lipid metabolism through a strong inhibition of de novo lipogenesis and maintained gut epithelial integrity. In the humanized SHIME^® model, these effects were associated with modulations of the intestinal microbiota characterized by a decreased Firmicutes/Bacteroidetes ratio. These data indicate that C. minuta DSM33407 is a convincing therapeutic candidate for the management of obesity and associated metabolic disorders.

Bread can vary in textural and nutritional attributes based on differences in the bread making process (e.g., flour type, fermentation agent, fermentation time). Four bread recipes (BRs) made with sourdough preferments (BR1, white flour; BR2, whole grain flour) or regular yeast breads (BR3, white flour; BR4, whole grain flour) were evaluated for texture, digestibility, and their effect on the metabolic activity and composition of the gut microbiota using texture profile analysis (TPA) coupled with in vitro upper gastrointestinal (GIT) digestion and colonic fermentation (Colon-on-a-plate™ model), using fecal samples from eight healthy human donors. TPA revealed significantly higher values for hardness, fracturability, gumminess, and chewiness, and significantly lower values for springiness, cohesiveness, and resilience with whole grain versus white breads (all p < 0.001); values for springiness, cohesiveness, and resilience were significantly higher for sourdough versus yeast bread (p < 0.001). Nutrient composition and bioaccessibility were generally comparable between sourdough and yeast bread with similar flours. Following simulation of upper GIT digestion, all BRs demonstrated good digestibility of minerals, carbohydrates, and proteins. Colonic fermentation revealed changes in gut microbiota composition, significant increases in short-chain fatty acids, and a significant decrease in branched short-chain fatty acids with all BRs versus a blank. Overall, new insights into wheat bread digestibility and colonic fermentation were provided, which are important aspects to fully characterize bread nutritional profile and potential.

The global protein demand is constantly on the increase, requiring sustainable and healthier protein alternatives for animal and human nutrition. Yeast-based proteins (YBPs) represent a non-negligible environmentally friendly fermentation-based solution with high nutritional quality and bioavailability. Although in vitro studies cannot reflect the full complexity of in vivo digestion, they are considered a useful alternative to animal models in assessing protein digestibility. Herein, TIM-1 (TNO gastro-intestinal model) was used to assess the digestibility profile of a proprietary edible YBP according to INFOGEST guidelines. We characterized the YBP’s digestibility and amino acid bio-accessibility and compared the YBP with milk-based references (casein and whey proteins). Each treatment was evaluated in triplicate during 5 h of digestion with hourly collection from jejunum and ileum compartments and final residual stomachal samples. Total nitrogen and free amino acid (FAA) were quantified. Size-exclusion chromatography and SDS-PAGE were also applied to assess the fate of protein hydrolysis over time. This study showed that all proteins were fully hydrolyzed upon one hour of digestion. YBPs were as good as milk-based references in terms of digestibility and small intestine absorption, reaching up to 60% of total bio-accessible protein after 5 h. Noteworthy, total YBP absorption followed a kinetics closer to that of whey protein in jejunum and ileum compartments. Our results are in line with a previous in vivo evaluation of YBPs where fecal N digestibility, PDCAAS, and DIAAS were evaluated. Altogether, our results suggest that YBPs could be a nutritionally relevant animal protein alternative.