A high-fat diet (HFD) can easily induce obesity and change the gut microbiota and its metabolites. However, studies on the effects of high-fat diets on the host have drawn inconsistent results. In this study, the unexpected results showed that the refined HFD increased gut microbiota diversity and short-chain fatty acids (SCFAs), causing an increase in energy metabolism. Further analysis revealed these changes were caused by the different fiber content in these two diets. Male C57BL/6J mice (4–5 weeks old) were fed either HFD or refined low-fat diet (LFD) for 14 weeks. The metabolic rates, thermogenesis, gut microbiome, and intestinal SCFAs were tested. The HFD triggered obesity and disturbed glucose homeostasis. Mice fed HFD ingested more fiber than mice fed LFD (p < 0.0001), causing higher intestinal SCFA concentrations related to the increased abundances of specific bacteria in the HFD group. Also, the HFD increased metabolic heat and up-regulated thermogenesis genes uncoupling protein 1(Ucp-1), peroxisome proliferator-activated receptor-γ coactivator-1α (Pgc-1α) expression in the brown adipose tissue (BAT). It was revealed by 16S rRNA gene sequencing that the HFD increased gut microbial diversity, which enriched Desulfovibrionaceae, Rikenellaceae RC9 gut group, and Mucispirillum, meanwhile, reduced the abundance of Lactobacillus, Bifidobacterium, Akkermansia, Faecalibaculum, and Blautia. The predicted metabolic pathways indicated HFD increased the gene expression of non-absorbed carbohydrate metabolism pathways, as well as the risks of colonization of intestinal pathogens and inflammation. In conclusion, the HFD was obesogenic in male C57BL/6J mice, and increased fiber intake from the HFD drove an increase in gut microbiota diversity, SCFAs, and energy expenditure. Meanwhile, the differences in specific nutrient intake can dissociate broad changes in energy expenditure, gut microbiota, and its metabolites from obesity, raising doubts in the previous studies. Therefore, it is necessary to consider whether differences in specific nutrient intake will interfere with the results of the experiments.

The incidence of obesity, which is closely associated with the gut microbiota and chronic inflammation, has rapidly increased in the past 40 years. Therefore, the probiotic-based modification of the intestinal microbiota composition has been developed as a strategy for the treatment of obesity. In this study, we selected four Bifidobacterium adolescentis strains isolated from the feces of newborn and elderly humans to investigate whether supplementation with B. adolescentis of various origins could alleviate obesity in mice. Male C57BL/6J mice fed a high-fat diet (HFD, 60% energy as fat) received one of the following 14-week interventions: (i) B. adolescentis N4_N3, (ii) B. adolescentis Z25, (iii) B. adolescentis 17_3, (iv) B. adolescentis 2016_7_2, and (v) phosphate-buffered saline. The metabolic parameters, thermogenesis, and immunity of all treated mice were measured. Cecal and colonic microbial profiles were determined by 16S rRNA gene sequencing. Intestinal concentrations of short-chain fatty acids (SCFAs) were measured by gas chromatography-mass spectrometry (GC-MS). The B. adolescentis strains isolated from the feces of elderly humans (B. adolescentis Z25, 17_3, and 2016_7_2) decreased the body weight or weight gain of mice, whilst the strain isolated from the newborn (B. adolescentis N4_N3) increased the body weight of mice. The B. adolescentis strains isolated from the elderly also increased serum leptin concentrations and induced the expression of thermogenesis- and lipid metabolism-related genes in brown adipose tissue. All the B. adolescentis strains alleviated inflammations in the spleen and brain and modified the cecal and colonic microbiota. Particularly, all strains reversed the HFD-induced depletion of Bifidobacterium and reduced the development of beta-lactam resistance. In addition, the B. adolescentis strains isolated from the elderly increased the relative abundances of potentially beneficial genera, such as Bacteroides, Parabacteroides, and Faecalibaculum. We speculate that such increased abundance of commensal bacteria may have mediated the alleviation of obesity, as B. adolescentis supplementation decreased the intestinal production of SCFAs, thereby reducing energy delivery to the host mice. Our results revealed that certain strains of B. adolescentis can alleviate obesity and modify the gut microbiota of mice. The tested strains of B. adolescentis showed different effects on lipid metabolism and immunity regulation, with these effects related to whether they had been isolated from the feces of newborn or elderly humans. This indicates that B. adolescentis from different sources may have disparate effects on host health possibly due to the transmission of origin-specific functions to the host.

Fermentation utilizing a combination of lactic acid bacteria (LAB) is known to enhance the nutritional value of wheat germ extract via the production of functional bioactive compounds. In this work, fermentation via compound LAB significantly enhanced the antioxidant activity of wheat germ extract. Compared to the unfermented group (CON), the in vitro antioxidant indices of Lactobacillus fermented wheat embryo extract were increased significantly: DPPH^·+/ABTS^·+ clearance (67.87 ± 3.48%/71.44 ± 5.90%), FRAP value (1.33 ± 0.02 μmol Trolox/10 mg), and active substance content including GSH (78.04 ± 1.43 μmol/g), total phenols (0.53 ± 0.01 mg GAE/10 mg), and total flavonoids (0.032 ± 0.01 mg/10 mg). Moreover, the antioxidant activity and substances of lactic acid bacteria-fermented wheat embryo extract were improved after gastrointestinal digestion compared with CON. In the erastin-induced Drosophila oxidative stress model, LFWGC intervention significantly improved behavioral performance (12.6 ± 3.78 s of tube climbing and 101.2 ± 7.98 jumps) and increased in vivo antioxidant levels: DPPH^·+·+ clearance by 31.75 ± 0.62%, ABTS^·+ clearance by 50.11 ± 0.82%, FRAP to 0.89 ± 0.03 μmol Trolox/10 mg, and GSH (116.30 ± 1.95 μmol/g), total phenols (0.117 ± 0.01 mg GAE/mg), and total flavonoids (0.027 ± 0.002 mg/g). Mechanistically, LFWGC enriched the intestinal flora with Levilactobacillus and Pseudomonas by restoring Tsf1 protein function, upregulating the expression of the TSF1 and GPX4 genes, and activating the pentose phosphate and a-lanine–aspartate-glutamate metabolic pathways, thereby synergistically enhancing the antioxidant defense system. LAB fermentation effectively enhanced the antioxidant capacity of wheat germ extract, providing a theoretical foundation for the development of functional foods.

Prometryn, a methylthio-s-triazine herbicide, persists widely in agricultural soils after long-term application, causing crop phytotoxicity and potential human health risks, and microbial degradation offers an eco-friendly, cost-effective strategy for remediation. In this study, three prometryn-degrading bacterial strains were isolated from long-term contaminated cornfield soil in Harbin, China, and identified as Pseudomonas sp. ZM-1, Achromobacter sp. ZM-2 and Stenotrophomonas sp. ZM-3 based on morphological, biochemical and 16S rDNA sequence analysis; strain ZM-3 is, to the best of our knowledge, the first reported pure-culture Stenotrophomonas isolate with confirmed prometryn-degrading capability. The three strains degraded 97.3%, 85.1% and 92.8% of 100 mg·L⁻¹ prometryn within 48 h respectively. The 1:1:1 synthetic consortium removed 96.8% of prometryn in 15 h, showing markedly superior degradation efficiency compared with single strains, and its 12-h degradation rate reached 96.87% with a half-life of 2.2 h following response surface optimization. In soil microcosms spiked with 20 mg·kg⁻¹ prometryn, the consortium reduced the pollutant half-life from 58.2 days to 7.8 days and achieved 96.3% removal after 30 days, alongside enhanced soil dehydrogenase, catalase and urease activities. High-throughput 16S rRNA gene sequencing revealed directional succession of the soil bacterial community, enrichment of core degrading taxa, and predicted enrichment of xenobiotic biodegradation pathways during remediation. Maize pot experiments confirmed that the consortium significantly alleviated prometryn phytotoxicity at the tested concentration, restoring plant growth parameters to 95–97% of the uncontaminated control. This study provides an efficient synthetic microbial consortium for bioremediation of prometryn-contaminated agricultural soils.

This study explored how the chemical composition and molecular structure of black rice influence its glycemic index (GI), as well as how different processing methods regulate these relationships. Eight black rice varieties were analyzed for their nutritional composition, physicochemical and rheological properties, and protein structural characteristics. Results showed that higher protein and lipid contents were associated with lower GI values, likely due to reduced starch accessibility and slower enzymatic digestion. Varieties with more ordered protein conformations and stronger molecular interactions exhibited lower GI, indicating that protein structural organization plays an important role in starch digestibility. Among the tested varieties, “Huamoxiang” showed the highest GI (68.40 ± 2.04), while “Yanghei No. 3” exhibited the lowest GI (49.27 ± 4.14). Low-GI varieties were further subjected to different processing treatments. Fermentation effectively reduced GI by 8.44% by limiting starch gelatinization and enzymatic susceptibility, while puffing maintained a low GI through molecular rearrangement of starch. In contrast, steaming disrupted ordered starch structures and significantly increased GI. Overall, these findings provide practical guidance for selecting black rice varieties and processing strategies to develop low-GI black rice products, supporting the design of functional foods and dietary management for glycemic control.