Tuna protein serves as a significant source of bioactive peptides, and its functional properties can be elucidated through predictive modeling, followed by experimental validation. In this study, the active polypeptides were obtained from tuna protein via enzymatic hydrolysis (TPP), and their peptide sequences were determined. Furthermore, the potential activity of these peptides was predicted, focusing on antioxidant peptides, and compared to the sequence library of known antioxidant peptides to identify common structural motifs. The accuracy of the prediction results was confirmed through in vitro antioxidant assays and molecular docking studies. We identified seven specific peptide segments derived from tuna protein that exhibit antioxidant potential, accounting for approximately 15% of all active peptides. Molecular docking and cell experiments were employed to provide compelling evidence for the presence of antioxidant peptides within tuna protein. This study not only lays a solid foundation for studying the structure of active peptides but also opens up a novel avenue for an expedited assessment of their properties.

Hypertriglyceridemia (HTG) can lead to the disorder of gut microbiota in mice, resulting in the increase of endotoxin content. HTG can also aggravate the damage of intestinal barrier function and intestinal bacterial translocation in acute pancreatitis (AP) mice. Toll‐like receptor 4 gene (Tlr4) knockout can significantly reduce gut permeability and endotoxin invasion in AP mice. In addition, HTG‐modulated gut microbiota could up‐regulate glycerophospholipid metabolism and increase lysophosphatidylcholine (LysoPC) content in a TLR4‐dependent manner, thereby aggravating pancreatic injury in AP.

Inflammatory bowel disease (IBD) is characterized by gut microbiota dysregulation and impaired intestinal barrier function. As a potential strategy to restore gut homeostasis, we investigated the potential of antimicrobial peptides derived from Clostridium butyricum (designated CBP) to modulate gut homeostasis and attenuate intestinal inflammation. Our initial characterization identified CBP as a 0.5-3 kDa fraction from C. butyricum fermentation broth, exhibiting potent direct antimicrobial activity against pathogenic strains including Escherichia coli, Salmonella enterica., and Staphylococcus aureus. Further genome and peptidome analysis revealed that CBP comprises novel antimicrobial peptides. In a murine model of LPS-induced intestinal injury, CBP preserved intestinal architecture, restored tight junctions, maintained goblet cells, and attenuated proinflammatory cytokines. These protective effects stemmed from selective gut microbiota modulation, with distinct effects under physiological versus inflammatory conditions. Physiologically, CBP increased beneficial genera and short-chain fatty acids (like acetic, propanoic and butyric acid) while decreasing Allobaculum. During inflammation, CBP restored the LPS-disrupted Bacillota/Bacteroidota ratio by suppressing pathobionts like Bacteroides and enriching barrier protective genera. These microbial shifts were associated with improved barrier function and suppressed pro-inflammatory cytokines. The unique advantages of CBP over its probiotic counterpart, C. butyricum, explain its superior efficacy in attenuating intestinal inflammation, positioning it as a promising postbiotic candidate. Amid the escalating global threat of antimicrobial resistance, our findings position CBP as a promising, targeted alternative to conventional antibiotics for treating human gastrointestinal disorders.

Late gestation is a critical period for regulating maternal peripartum physiological metabolism and gut microbiota balance. Fermented diets have been widely recognized as effective exogenous nutritional interventions capable of modulating the maintenance of gut microbiota homeostasis. However, the mechanism through which fermented diets modulate the gut microbiota in late-gestation remains poorly understood. In this study, an in vitro fermentation model combined with chemical composition analysis, untargeted metabolomics, and high-throughput sequencing was employed to investigate the metabolic alterations during soybean meal (SBM) fermentation and the regulatory effects of fermented soybean meal (FSBM) on gut microbiota of late-gestation sows. The findings revealed that fermentation significantly increased the levels of crude protein, lactic acid, acid-soluble protein, lysine, histidine, and total amino acids of SBM. Conversely, the levels of crude fiber, NDF, ADF, starch, and non-starch polysaccharides were markedly reduced, compared to the unfermented group. A total of 941 differentially expressed metabolites were identified between SBM and FSBM. Specifically, FSBM elevated the levels of lactic acid, L-pyroglutamic acid, 2-aminoisobutyric acid, and tyrosine, while substantially decreasing the levels of raffinose, sucrose, and stachyose. Metabolic pathway analysis identified glutathione metabolism, tyrosine metabolism, and pantothenate and coenzyme A (CoA) biosynthesis as the key pathways involved in SBM fermentation. In vitro fermentation experiments demonstrated that FSBM substantially increased the production of short-chain fatty acids (SCFAs) and notably increased the relative abundance of sows gut commensal Lactobacillus and Limosilactobacillus in late gestation. In summary, this study demonstrated that co-fermentation with bacteria and enzymes pretreatment of soybean meal reduced fiber components and enriched bioactive metabolites, optimizing intestinal microbial composition and increasing SCFA production in late-pregnant period. The present study provides novel insights into the regulatory effects of fermented diets on gut microbiota in late-gestation period from the perspectives of nutritional composition and metabolites.

Weaning stress impacts piglet performance, prompting antimicrobial resistance concerns from antibiotic overuse. Clostridium butyricum -derived antimicrobial peptides (CBP) show potentials as a safe, effective antibiotic alternative. We initially characterized novel antimicrobial peptides within the CBP fraction, synthesizing and confirming their potent activity. This study evaluated CBP’s effects on intestinal health and growth performance of weaned piglets using a lipopolysaccharide (LPS)-induced inflammation model. Fifty weaned Jinhua piglets (45 days, 9.95 ± 2.03 kg) were randomly allocated to control group (CON) and CBP group ( n = 25), with five replicates each. Piglets in the CBP group were orally administered 3 mL of CBP daily (145.59 mg of total peptide) for 21 days, while the CON group received sterile water. During this period, CBP significantly improved growth performance, evidenced by increased average daily gain ( P = 0.047) and reduced feed conversion ratio ( P = 0.015), alongside a decrease in diarrhea incidence ( P < 0.05). To further investigate the mechanism, a subset of animals from each group was challenged with LPS on day 21 to induce intestinal inflammation. Mechanistically, CBP enhanced intestinal barrier functions by optimizing crypt architecture and upregulating tight junction proteins expression ( P < 0.05). CBP also exerted a potent anti-inflammatory effect, substantially reducing pro-inflammatory cytokines ( P < 0.05) and suppressing NLRP3 inflammasome activation. Integrated microbiome and metabolomic analyses revealed CBP modulated the gut microbiota by increasing beneficial bacteria Lactobacillus and Coprococcus ( P < 0.05) and elevating protective metabolites, including butyrate and hyocholic acid ( P < 0.05). In conclusion, our findings demonstrate that CBP supplementation effectively promotes piglet growth and alleviates intestinal injury by regulating the gut microbiota and associated metabolic profiles. These effects are mediated through enhanced intestinal barrier functions and suppressed inflammation via the GPR43-NLRP3 pathway. This study provides strong evidence for CBP as a promising, safe alternative to antibiotics.

Comprehensive maternal nutritional interventions, particularly during late gestation, enhance perinatal outcomes and support long-term maternal-offspring health by modulating the microbiota. Fermented diets are recommended for inclusion in dietary guidelines during gestation, yet the specific metabolites after fermentation and their specific regulatory effects on gut microbiota during late gestation remain unclear. This study investigates the functional benefits of a fermented wheat bran–soybean meal–Broussonetia papyrifera mixed substrate (FMS) on the late-gestation gut microbiota using an in vitro fermentation model. The FMS was first fermented for 72 h with bacterial and enzymatic agents (2% v/v), then anaerobically incubated with fecal inocula from Jinhua pigs. Fermentation significantly enhanced nutritional profiles, increasing crude protein and amino acids while reducing fiber components (neutral detergent fiber, acid detergent fiber, and non-starch polysaccharide, p < 0.05). Metabolome analysis revealed a significant increase in the abundance of organic acids, amino acids, and short peptides in FMS, along with the enrichment of D-amino acid and sphingolipid pathways (p < 0.05). In addition, FMS significantly increased the abundance of Limosilactobacillus and Lactobacillus, as well as short-chain fatty acids production, compared to the unfermented group (p < 0.05). These findings demonstrate that fermentation pretreatment reduces fiber components, enhances flavor compounds and bioactive metabolites, thereby optimizing microbial utilization and increasing short-chain fatty acids production.