Threonine (Thr), an essential amino acid for animals and the limiting amino acid in swine and poultry diets, which plays a vital role in the modulation of nutritional metabolism, macromolecular biosynthesis, and gut homeostasis. Current evidence supports that the supplementation of Thr leads to benefits in terms of energy metabolism. Threonine is not only an important component of gastrointestinal mucin, but also acts as a nutritional modulator that influences the intestinal immune system via complex signaling networks, particularly mitogen-activated protein kinase (MAPK) and the target of the rapamycin (TOR) signal pathway. Threonine is also recognized as an indispensable nutrient for cell growth and proliferation. Hence, optimization of Thr requirement may exert a favorable impact on the factors linked to health and diseases in animals. This review focuses on the latest reports of Thr in metabolic pathways and nutritional regulation, as well as the relationship between Thr and relevant physiological functions.

The composition of skeletal muscle fiber types affects the quality of livestock meat and human athletic performance and health. L-arginine (Arg), a semi-essential amino acid, has been observed to promote the formation of slow-twitch muscle fibers in animal models. However, the precise molecular mechanisms are still unclear. This study investigates the role of Arg in skeletal muscle fiber composition and mitochondrial function through the mTOR signaling pathway. In vivo, 4-week C56BL/6J male mice were divided into three treatment groups and fed a basal diet supplemented with different concentrations of Arg in their drinking water. The trial lasted 7 weeks. The results show that Arg supplementation significantly improved endurance exercise performance, along with increased SDH enzyme activity and upregulated expression of the MyHC I, MyHC IIA, PGC-1α, and NRF1 genes in the gastrocnemius (GAS) and quadriceps (QUA) muscles compared to the control group. In addition, Arg activated the mTOR signaling pathway in the skeletal muscle of mice. In vitro experiments using cultured C2C12 myotubes demonstrated that Arg elevated the expression of slow-fiber genes (MyHC I and Tnnt1) as well as mitochondrial genes (PGC-1α, TFAM, MEF2C, and NRF1), whereas the effects of Arg were inhibited by the mTOR inhibitor rapamycin. In conclusion, these findings suggest that Arg modulates skeletal muscle fiber type towards slow-twitch fibers and enhances mitochondrial functions by upregulating gene expression through the mTOR signaling pathway.

Studies demonstrated that Bacillus coagulans (B. coagulans) as a dietary additive enhanced broiler growth performance, yet its mechanisms of action modulation remained unclear. Therefore, this study investigated effects of dietary B. coagulans BCH0 (1 × 10⁹ CFU/kg) on growth performance, intestinal morphology, gut microbiota, and ileal transcriptomics in Arbor Acres broilers using a completely randomized design. A total of 200 one-day-old broilers were allocated to control (Con, basal diet) and experimental (BCH0, basal diet + 1 × 10⁹ CFU/kg B. coagulans BCH0) groups (10 replicates/group, 10 birds/replicate) over a 42-day trial. The results revealed that BCH0 significantly increased body weights (BW) at 21 and 42 days (p < 0.05), improved the average daily gain (ADG) during the starter (1–21 days) and overall phases (1–42 days), and reduced the ratio of feed intake to body weight gain (F/G) across all phases (p < 0.05). Duodenal morphology analysis indicated a BCH0 elevated villus height (+16.9%, p < 0.01) and villus height/crypt depth (V/C) (p < 0.01) and no significant differences in crypt depth (p = 0.46). In the ileum, the BCH0 group exhibited a significantly greater villus height (p < 0.01), crypt depth (p < 0.05), and V/C (p < 0.05) than the Con group. Microbiota analysis revealed no significant differences in α-diversity or β-diversity, but phylum-level shifts involved an increase in Firmicutes and a reduction in Actinobacteriota in the BCH0 group. At the genus level, dominance shifted from Romboutsia (Control group) to Lactobacillus (BCH0 group), accompanied by marked reductions in Turicibacter, Ldatus_arthromitus, and Rothia. Ileal transcriptomics identified 605 differentially expressed genes, with KEGG enrichment highlighting activated nutrient assimilation pathways (p < 0.05), including carbohydrate, mineral, fat, and protein digestion/absorption. These findings collectively demonstrated that B. coagulans BCH0 enhanced broiler growth through the synergistic modulation of beneficial microbiota, the upregulation of nutrient metabolism genes, and intestinal architectural optimization, supporting its role as a sustainable microbial additive for enhancing poultry productivity and gut health.

The overuse of antibiotics has accelerated the evolution and mutation of drug-resistant bacteria, creating an urgent need for novel antimicrobial drugs and feed additives. Antimicrobial peptides, with their unique membrane-disrupting mechanism that resists the development of resistance, hold promise as antibiotic alternatives. To overcome the limitations of natural antimicrobial peptides—such as poor stability, susceptibility to protease degradation, and short in vivo half-lives—self-assembling peptide technology has emerged. This approach employs non-covalent interactions to orderly assemble monomeric peptides into stable, structured nanomaterials like nanofibers, nanotubes, and hydrogels. This paper outlines the molecular design principles and smart response mechanisms of antimicrobial peptide nanoassemblies, elucidates their core advantages over monomeric peptides, summarizes their application scenarios in anti-infection fields, and discusses limitations and future directions across various domains. It provides insights for future antimicrobial peptide design.

(1) This study explored Lacticaseibacillus rhamnosus MS27, a newly isolated strain, as a potential probiotic candidate for alleviating the onset and severity of ulcerative colitis (UC). (2) L. rhamnosus MS27 was isolated and subjected to biochemical identification, antibiotic sensitivity testing, and antibacterial activity assessment. Dextran sulfate sodium (DSS) colitis model mice were used to evaluate its alleviating effects. In this study, 16S rRNA microbiome and eukaryotes reference transcriptome analyses were conducted to investigate its impact on intestinal microbial ecology and potential molecular mechanisms. (3) L. rhamnosus MS27 exhibits high acid tolerance at pH 3.23 and maintains a high viable bacterial count for 24 h. It can utilize sucrose, lactose, maltose, inulin, esculin, salicin, and mannitol but not raffinose, and it is sensitive to carbenicillin, erythromycin, tetracycline, chloramphenicol, clindamycin, and penicillin. It effectively increases the abundance of beneficial microbes, particularly Akkermansia, Muribaculaceae, and Limosilactobacillus reuteri (p < 0.05), while significantly reducing microorganisms linked to human pathogens causing diarrhea and gastroenteritis (p < 0.05). Transcriptomic analysis demonstrated that the expression levels of Igkv16-104 and C1qtnf3 were significantly downregulated in the presence of L. rhamnosus MS27 treatment compared to DSS treatment alone (p < 0.05). Further analysis revealed significant differences in genes related to immune functions, antigen presentation, and immune cell markers, indicating potential protein–protein interaction networks, particularly among genes of the major histocompatibility complex (MHC). (4) L. rhamnosus MS27, as a novel strain, demonstrates a significant capacity to alleviate inflammatory phenotypes. L. rhamnosus MS27 exhibits distinctive metabolic characteristics in lactic acid utilization, acetic acid and oleic acid production. Furthermore, it contributes to systemic homeostasis regulation by modulating Turicibacter to link intestinal microbiota composition with host immune function.