Probiotics and Antimicrobial Proteins最新文献

With obesity posing a growing global health burden, probiotic interventions are gaining attention as potential therapeutic strategies. This study moves beyond conventional single-strain approaches by developing a rationally designed multi-strain consortium sourced from the under-explored microbial niche of traditional koumiss. Sixteen lactic acid bacterial strains were isolated and screened using key in vitro lipid-lowering indicators. Two high‑performing strains, Lactobacillus plantarum SR6 and Enterococcus faecalis SM5, were selected and formulated into a 1:1 composite (SR6‑SM5). The composite not only exhibited synergistically enhanced functional properties-including strong gastrointestinal tolerance, with a survival rate of over 95.7% in gastric juice and over 76% in intestinal juice, high adhesion potential (hydrophobicity 93.00 ± 0.25%; auto-aggregation 90.58 ± 0.31%), notable antioxidant activity (ABTS⁺ and DPPH· scavenging rates > 87%), and antibacterial effects-but also demonstrated a comprehensive safety profile with no hemolytic, cytotoxic, or acute oral toxicity observed in mice. By integrating efficacy, safety, and probiotic suitability into a single tailored consortium, this work provides a novel, functionally enhanced probiotic candidate with strong potential for further development in obesity‑related functional foods.

Gamma-aminobutyric acid (GABA) is associated with depressive-like behaviours and influences the gut-brain axis through vagal nerve-dependent mechanisms. Studies indicate that depression can be reversed with GABA administration, but the neuroprotective potential of GABA-producing bacteria remains underexplored. Subtractive screening identified five potential GABA-producing strains out of 95 distinct isolates, which were subsequently confirmed using thin-layer chromatography, NMR, and mass spectrometry. All five strains survived in acidic conditions, with survivability rates of 72-84%, and in 0.3% bile, with survivability rates of 93-96%. The selected strains showed higher hydrophobicity to chloroform, possessed free radical scavenging activities, and were capable of forming stronger biofilms. This study identifies Limosilactobacillus fermentum PB02 and Levilactobacillus brevis MM as potential GABA-producing probiotics. The neuroprotective effects of GABA-containing cell-free supernatant (CFS) were tested in stress-challenged Human Neuroblastoma SH-SY5Y cell lines. The CFS supplementation increased cell viability after exposure to high glucose and lipopolysaccharide, and improved viability in a glutamate-induced excitotoxicity assay, indicating the multifactorial in vitro neuroprotective potential. This study enhanced the viability of cells by 20-25% viability in cells challenged with 250mM glucose and 1 µg/mL LPS, and in the glutamate-mediated excitotoxicity assay. Additionally, L. fermentum PB02 and L. brevis MM emerged as promising psychobiotic candidates with neuroprotective effects, as indicated by Principal Component Analysis and weighted scoring matrix analysis. By integrating clustering analysis, we demonstrate that isolated strains can be promising candidates showing neuroprotective potential using in vitro methods. Further in vivo validation will be required to confirm these effects.

This study focused on the isolation and comprehensive evaluation of a postbiotic synthesized by E. coli Nissle 1917. The research specifically investigated its diverse biological activities, including its potential antibacterial, bacteriostatic, bactericidal effects, and its antioxidant capacity. The primary objective was to determine the postbiotic's efficacy in reducing semen bacterial load and mitigating oxidative stress, enhancing the quality and structural integrity. The results indicated that E. coli Nissle 1917 postbiotic exhibited significant antibacterial activity against K. pneumoniae, S. epidermidis, and S. aureus. The bacteriostatic effect was observed against K. pneumoniae (900 µg/mL), E. coli (1800 µg/mL), P. aeruginosa (1500 µg/mL), S. aureus (1200 µg/mL), S. epidermidis (900 µg/mL), and B. subtilis (1500 µg/mL). The bactericidal effect was most pronounced against K. pneumoniae and S. epidermidis, which were the most sensitive, with a minimum bactericidal concentration (MBC) of 1000 µg/mL, followed by S. aureus (1400 µg/mL), P. aeruginosa and B. subtilis (1650 µg/mL). The main components of the postbiotic are docosanoic acid, 1,2,3-propanetriyl ester (0.90%), stearic acid, 3-(octadecyloxy)propyl ester (1.24%), 1-methyl-2-pyrrolidineethanol (1.49%), 4(3 H)-pyrimidinone / 1 H-imidazole-4,5-dihydro-2-methyl (0.96% / 0.87%), 10-octadecenoic acid methyl ester and similar C18 fatty acid methyl esters (3.74%), cyclohexanol, 1R-4-acetamido-2,3-cis-epoxy (3.34%), 2-myristynoyl-glycinamide (1.85%), 1-monolinoleoylglycerol trimethylsilyl ether (1.81%), and glycine, N-3,5,7,12-tetrakis(trimethylsiloxy)cholan-24-yl derivative (0.82%). Supplementation with 1000-2000 µg/mL postbiotic significantly improved sperm motility (25.7%, and 29.5%), viability (26.8%, and 34%), membrane integrity (22.2%, and 27.1%), and kinematic parameters compared to the control group (p < 0.01, respectively). Postbiotic addition also increased the percentage of live sperm with intact acrosome and reduced the percentages of live and dead sperm with detached acrosome. Postbiotic addition (250, 500, 1000 and 2000 µg/mL) significantly improved total antioxidant capacity (35.6, 36.9, 52 and 63%), reduced oxidative stress markers such as malondialdehyde (6.1, 8.7, 19.5 and 22.9%), and nitric oxide (20, 28.2, 36.4 and 38.9%, respectively) and decreased the percentage of apoptotic sperm (26, 46.5, 48.9 and 51.2%) in post-thawed semen compared to control group (p < 0.01). Postbiotic supplementation preserved sperm ultrastructure and enhanced pregnancy rates as well as reduced the bacterial load in post-thawed semen (p < 0.05). In summary, the E. coli Nissle 1917 postbiotic acts as a crucial protective agent. By exerting antimicrobial, anti-apoptotic, and antioxidant activities, it effectively regulates the semen's antioxidant status and maintains the quality of cryopreserved buffalo sperm.

The increasing incidence of antibiotic-resistant Staphylococcus aureus infections has created a critical need for alternative therapeutic agents that are effective and safe. Antimicrobial peptides are considered attractive candidates in this context. A scorpion peptide derivative, designated HP-H1K8, was designed in this study and was then found to possess potent activity against methicillin-resistant S. aureus (MRSA), coupled with low toxicity and high serum stability. The mechanism of action was identified as bacterial membrane disruption. In a mouse model of MRSA-induced skin infection, the topical application of HP-H1K8 was shown to significantly reduce bacterial load in the wound and enhance the healing process. Additionally, the peptide was not prone to inducing bacterial resistance. It is concluded that HP-H1K8 represents a potent topical agent for the treatment of skin infections caused by drug-resistant S. aureus.

Antimicrobial peptides (AMPs) are promising candidates against antimicrobial resistant pathogens due to their lower likelihood of generating resistance. Enterococcus spp., a common group of gut probiotics, are essential sources of bacteriocins that make them a valuable source for novel AMPs discovery. In this study, we aimed to systematically identify AMPs by analyzing the transcriptomes of Enterococcus species using computational methods. Briefly, the transcriptomes of diverse Enterococcus species were downloaded, processed, de novo assembled, and translated into open reading frames. AMPs were predicted and filtered based on physicochemical and structural criteria. The antibacterial activity of the selected candidate has been evaluated against drug-resistant bacteria. We identified 14 candidate AMPs with net positive charge ≥ + 3, lengths of 10-25 residues, non-toxicity, non-hemolytic properties, antibiofilm activity, and stable secondary structure, capable of interacting with bacterial membranes, using computational tools. Among these, EM_4 exhibited optimal characteristics and was selected for further evaluation. In vitro, EM_4 demonstrated potent inhibition of both susceptible and extensively drug-resistant (XDR) Staphylococcus aureus and Acinetobacter baumannii strains (MIC 2.5-20 ± 0.0 µM; MBC 5.0-20.0 µM), retained activity under various temperature and salt conditions, showed significant antibiofilm effects (40-80 ± 0.0 µM), low hemolytic activity (3.2%), and induced dose- and time-dependent bacterial membrane disruption confirmed by DNA-release assays. In conclusion, our research highlights computational AMP discovery efficacy and presents EM_4 as a promising candidate for the development of next-generation antimicrobials targeting pathogens.

The rising demand for health-promoting beverages, kombucha presents significant opportunities for scientific innovation and commercial growth. Symbiotic culture of bacteria and yeast (SCOBY), which includes acetic acid bacteria (AAB), lactic acid bacteria (LAB), and several yeast species, plays a major role in kombucha fermentation. During fermentation, kombucha produces bioactive compounds mainly catechins, theaflavins, tannins, and organic acids that enhance health efficacy and probiotic properties, supporting gut health and non-communicable disease prevention. The present study emphasizes, nutritional qualities of kombucha through different Komagataeibacter starter cultures and alternative substrates such as herbal infusions and fruit extracts. This review also highlights the role of AAB, LAB, and Yeast in the production mechanism of the kombucha beverage by the different microbial strains of microbial species and the fibril network of bacterial cellulose. This study further explains the bioactivities in the human body, especially mechanisms of action in the intestine through fundamental signaling pathways such as PIK3-AKT, MAPK, NFκB, PPARγ, and JAK-STAT. Therapeutic efficacy of kombucha, including various substrate-based antioxidants, antimicrobials, synergistic impact, delivery mechanism of anticancer, anti-diabetic insulin, and glycaemic responses, regulations of inflammatory markers (ILs) in anti-obese properties, has also been reviewed. Further, it is necessary to develop the advanced kombucha beverage qualities through metagenomics, metabolomics. Future studies should address these research gaps to ensure controlled microbial and probiotic stability, validate metabolites availability, and explore innovative applications for improved functionality and shelf-life.

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract that significantly impairs patient quality of life. Probiotics have shown therapeutic potential in modulating gut microbiota and alleviating intestinal inflammation. However, the clinical application is limited by poor viability and low bioavailability in the harsh gastrointestinal environment. These challenges have driven increasing interests in the development of effective probiotic delivery systems. This review summarized the key mechanisms of probiotics exerting beneficial effects in the human gut and systematically discussed recent advances in probiotic delivery platforms, including emulsions, nanoparticles, hydrogels, microspheres, and nanofibers. In addition, an overview of commonly used evaluation strategies was provided, focusing primarily on in vitro characterization and preclinical evidence. These assessment approaches include animal models of IBD, histological examination, imaging techniques, immunological analyses, and gut microbiota profiling. Well-designed delivery systems can effectively protect probiotics, enhance their stability and bioavailability in the gastrointestinal tract, and thereby improve their therapeutic efficacy against intestinal inflammation. Nevertheless, the clinical translation of probiotic delivery systems remains limited. Key challenges include insufficient safety evaluation, lack of standardized quality control and potency assessment, difficulties in large-scale manufacturing, and unclear regulatory pathways for live biotherapeutic products. Addressing these barriers will be essential for advancing probiotic delivery systems from experimental studies toward clinical application in IBD prevention and treatment.

This study aimed to isolate and identify a fiber-degrading probiotic strain from traditional yak yogurt on the Qinghai-Tibet Plateau and evaluate its effects on rumen fermentation and microbial metabolism. Through carboxymethyl cellulose (CMC) screening, filter paper degradation, and straw degradation tests, a lactic acid bacterium-Pediococcus pentosaceus JASB0677-was obtained, with a straw degradation rate of 18.74%. P. pentosaceus JASB0677 exhibited tolerance to simulated gastric (pH 3.0, 1% pepsin, survival rate: 69.01%) and intestinal juices (pH 8.0, 1% trypsin, 63.18%) and showed bile salt resistance at 0.1%, 0.2%, and 0.3% concentrations (survival rates: 79.05%, 63.34%, and 52.32%, respectively). It also demonstrated strong antibacterial activity, with an inhibition zone diameter of 20.03 mm against Salmonella, and antioxidant activity, with 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging rates of 46.52% and 39.17%, respectively. In vitro rumen fermentation revealed that P. pentosaceus JASB0677 significantly increased acetate and total volatile fatty acids (TVFAs) concentrations while reducing ammonia nitrogen levels (p < 0.05). 16 S rRNA sequencing revealed that P. pentosaceus JASB0677 altered the rumen microbial composition by increasing the relative abundance of Proteobacteria, Actinobacteria, Enterobacter, Klebsiella, and Christensenellaceae_R-7_group. Metabolomic analysis revealed significant modulation of several metabolic pathways, especially those related to amino acid and lipid metabolism. Correlation analysis indicated that acetate and TVFAs concentrations were significantly positively correlated with the abundances of Proteobacteria, Actinobacteria, Enterobacter, and Klebsiella, as well as specific metabolites including mevalonic acid and L-leucine, while ammonia nitrogen showed the opposite trend (p < 0.05). These results suggest that P. pentosaceus JASB0677 is a promising candidate functional feed additive for enhancing fiber utilization, maintaining microbial homeostasis, and improving rumen fermentation in ruminants.