Constipation is one of the most common gastrointestinal complaints worldwide. This study was performed to determine whether Bifidobacterium adolescentis exerts inter-strain differences in alleviating constipation induced by loperamide in BALB/c mice and to analyze the main reasons for these differences. BALB/c mice underwent gavage with B. adolescentis (CCFM 626, 667, and 669) once per day for 17 days. The primary outcome measures included related constipation indicators, and the secondary outcome measures were the basic biological characteristics of the strains, the concentration changes of short-chain fatty acids in feces, and the changes in the fecal flora. B. adolescentis CCFM 669 and 667 relieved constipation symptoms by adhering to intestinal epithelial cells, growing quickly in vitro and increasing the concentrations of propionic and butyric acids. The effect of B. adolescentis on the gut microbiota in mice with constipation was investigated via 16S rRNA metagenomic analysis. The results revealed that the relative abundance of Lactobacillus increased and the amount of Clostridium decreased in the B. adolescentis CCFM 669 and 667 treatment groups. In conclusion, B. adolescentis exhibits strain-specific effects in the alleviation of constipation, mostly due to the strains’ growth rates, adhesive capacity and effects on the gut microbiome and microenvironment.

In this study, lactic acid bacteria (LAB) fermentation and β-galactosidase catalysis methods were combined to increase the lactulose concentration and reduce the galactose and lactose content in a hot-alkaline-based system. The optimal conditions for chemical isomerization were 70 °C for 50 min for lactulose production, in which the concentration of lactulose was 31.3 ± 1.2%. Then, the selection and identification of LAB, which can utilize lactose and cannot affect lactulose content, were determined from 451 strains in the laboratory. It was found that Lactobacillus salivarius TM-2–8 had weak lactulose utilization and more robust lactose utilization. Lactobacillus rhamnosus grx.21 was weak in terms of lactulose utilization and strong in terms of galactose utilization. These two strains fermented the chemical isomerization system of lactulose to reduce the content of lactose and galactose. The results showed that the lactose concentration was 48.96 ± 2.92 g/L and the lactulose concentration was 59.73 ± 1. 8 g/L for fermentation lasting 18 h. The β-galactosidase was used to increase the content of lactulose in the fermented system at this time. The highest concentration of 74.89 ± 1.68 g/L lactulose was obtained at an enzymatic concentration of 3 U/mL and catalyzed at 50 °C for 3 h by β-galactosidase.

Fermentation is an effective method to enhance the bioactivity of plant proteins, yet the link between the functionality and conformational state of fermented soybean 11S protein (F11S) requires clarification. This study first evaluated the antioxidative efficacy of F11S and its application in emulsion systems, followed by a mechanistic investigation into its structural evolution. Results showed that the bioactivity of F11S was strictly fermentation-time-dependent, reaching its peak at 16 h. At this stage, F11S exhibited maximal scavenging capacities for ·OH (84.51 ± 2.53%) and DPPH radicals (93.84 ± 2.62%). Crucially, in a Tween 20 emulsion system, the F11S-16h fraction demonstrated superior oxidative stability, maintaining the lowest peroxide value (4.33 ± 0.53 mmol/kg) after 15 days of storage. To elucidate the mechanism behind this enhanced functionality, structural analysis was conducted. It revealed that while surface hydrophobicity peaked at 12 h due to protein unfolding, extended fermentation to 16 h induced a refolding process, guiding the protein into a thermodynamically stable conformation. These findings indicate that the stable refolded structure formed at 16 h, rather than maximal hydrophobicity, is the key determinant for the superior antioxidant performance and emulsion stabilizing ability of F11S.