Search Results (48)

Heavy metal pollution from coal gangue severely degrades mine soil structure and threatens landscape ecological stability. Particularly, γ-polyglutamic acid (γ-PGA), a green biopolymer, offers potential applications for pollution remediation while supporting ecological restoration. To evaluate γ-PGA’s efficacy in immobilizing Pb, Cd, and Zn in gangue-based soil and clarify its regulatory mechanism for landscape-friendly remediation, soil samples from a 3-year-weathered gangue hill in the Liupanshui mining area were subjected to indoor leaching experiments with different γ-PGA doses, combined with material characterization and Density Functional Theory (DFT) simulations. The results showed that the optimal γ-PGA dose was 6 g/kg, achieving 93.25% Pb immobilization and reducing Cd/Zn migration risk by over 30%; γ-PGA acted via carboxyl-amide dual-site chelation and hydrogen-bonded agglomeration, forming stable aggregates that inhibited metal migration. DFT calculations confirmed strong chelation for Cu²⁺ (−59.54 kcal/mol, BSSE-corrected: −57.23 kcal/mol), while Pb²⁺ and Cd²⁺ showed weaker binding (−8.32 kcal/mol and −5.67 kcal/mol, BSSE-corrected: −6.15 kcal/mol and −3.89 kcal/mol, respectively), indicating multi-pathway immobilization mechanisms. This study provides a theoretical basis for applying γ-PGA in mine landscape ecological restoration. Full article

A mixture of poultry litter (PL) and biochar (BC) was composted over 120 days in a bioreactor. To assess the impact on the stability of organic matter, the bioavailability of heavy metals, and ecotoxicity, the PL+BC biomass was supplemented with 0.5% (w/w) γ-polyglutamic acid (PGA), superphosphate (SPP) and smectite-silica clay (SSC) relative to the dry matter. Incorporating PGA, SPP, and SSC additives into PL+BC increased total carbon content by an average of 6%, compared to PL+BC without additives. The SSC additive proved to be more effective in increasing the humic acid carbon content, raising Cha by an average of 23% relative to PGA and SPP treatments. The incorporation of biochar into PL led to a substantial increase in nonhydrolizing carbon content, while the enrichment of composts with PGA, SPP, or SSC resulted in an escalation in this form of carbon by an average of over 7% compared to PL+BC. The lowest amounts of metals extracted with water and the lowest RAC values were obtained for PL+BC+SPP compost. The additives used stabilized the composts more quickly and reduced their toxicity. The classification of PL compost was designated as class III, whereas composts that incorporated additives were classified as class II toxicity. The study findings substantiated the necessity to incorporate additives during the biological processing of poultry litter. Full article

Efficient microbial assimilation of high-concentration ammonium nitrogen and its conversion into value-added bioproducts represent a pivotal yet underexplored strategy for sustainable nitrogen management. Here, we report a newly isolated Bacillus velezensis strain, GY1, with a robust intrinsic capacity for simultaneous NH₄⁺-N assimilation and γ-polyglutamic acid (γ-PGA) biosynthesis. Under optimized conditions (37 °C, pH 7.0, C/N = 12:1), GY1 achieved 76.5% removal of ammonium nitrogen (400 mg/L) with negligible nitrite accumulation (<0.02 mg/L), indicating assimilation rather than nitrification. Transcriptomic analysis revealed a coordinated metabolic flux wherein the glutamine synthetase - glutamate synthase pathway GS-GOGAT pathway supplies glutamate for γ-PGA synthesis, while polymerization further facilitates ammonium sequestration via electrostatic interactions. GY1 produced up to 612.8 mg/L γ-PGA, and genetic overexpression of capB synchronized these pathways, enhancing both ammonium assimilation (87.4%) and γ-PGA yield (843.9 mg/L). Notably, this metabolic coupling remained resilient in complex substrates, achieving 68.8% ammonium removal and 220.7 mg/L γ-PGA production in untreated biogas slurry. Together, these findings establish GY1 as a metabolically robust platform linking nitrogen assimilation with biopolymer synthesis, offering a mechanistic framework for circular nitrogen economies. Full article

Aging is closely associated with oxidative stress, which contributes to functional decline and increased vulnerability to neurodegenerative diseases. Natural antioxidants, such as Chlorella Growth Factor (CGF) and γ-polyglutamic acid (γ-PGA), possess antioxidant and anti-aging properties; however, their combined effects remain unknown. This study investigated the potential synergistic effects of CGF and γ-PGA supplementation in senescence-accelerated mouse-prone 8 (SAMP8) mice, a model characterized by early cognitive decline, locomotor deficits, and elevated oxidative DNA damage. Three-month-old male SAMP8 mice (n = 40) were divided into four groups: control, CGF (49.2 mg/kg BW/day), γ-PGA (20.5 mg/kg BW/day), and combined CGF + γ-PGA (69.7 mg/kg BW/day), and were treated for 13 weeks. Behavioral and physiological assessments included locomotor activity, aging index, and cognitive function (passive and active avoidance tests). Biochemical analysis focused on brain 8-hydroxy-2′-deoxyguanosine (8-OHDG) as a biomarker of oxidative DNA damage. Supplementation with CGF and γ-PGA, particularly in combination, significantly improved locomotor activity, aging scores, and cognitive functions. Notably, the combined treatment yielded the greatest reduction in brain 8-OHDG levels. These findings indicate that CGF and γ-PGA, when administered together, exert enhanced protective effects against functional and molecular aging. In conclusion, long-term supplementation with CGF and γ-PGA protects against aging-related decline in SAMP8 mice. This study highlights the potential of CGF and γ-PGA as safe, natural candidates for the development of functional foods or nutraceuticals aimed at promoting healthy aging and reducing oxidative stress-associated disorders. Full article

Optimizing calcium metabolism is crucial for skeletal development and overall productivity in growing ruminants. Twenty-four Sunite lambs were randomly assigned to four groups and fed 0, 0.6, 1.2, or 2.4 g/(d·head) of γ-PGA for 60 days. Growth performance, serum parameters, duodenal morphology and calcium transporter expression, bone microarchitecture, and duodenal microbiota were analyzed. Supplementation with 1.2 g/(d·head) of γ-PGA (the M group) yielded optimal results, significantly improving final body weight and size. It enhanced duodenal health, evidenced by increased villus height, crypt depth, and microvilli density. Crucially, this dose significantly upregulated the expression of key duodenal calcium transporters (TRPV5/6, CaBPD9k, PMCA, VDR, claudin-12) and altered systemic calcium-regulating hormones (elevated calcitriol, PTH, FGF23). Bone micro-CT analysis revealed changes in trabecular architecture indicative of active remodeling. 16S rRNA sequencing and weighted OTU co-expression network analysis (WOCNA) revealed that γ-PGA reshaped the duodenal microbiota and identified core microbial modules strongly associated with host phenotypes. Genera such as [Eubacterium]_ruminantium_group, Fusicatenibacter, and Prevotella emerged as central hubs. In conclusion, dietary γ-PGA at 1.2 g/(d·head) enhances calcium absorption and bone metabolism in lambs through a coordinated modulation of intestinal integrity and calcium transport, systemic endocrine responses, and the duodenal microbial community, with specific microbiota identified as potential key mediators associated with these effects. Full article

Background/Objectives: Wound infections caused by multidrug-resistant Gram-negative bacteria, such as Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii, pose a major clinical challenge. This study evaluated the interactions between gamma-polyglutamic acid (γ-PGA), cefiderocol, and silver nanoparticles (AgNPs) within multilayer wound dressing configurations. The primary goal was to clarify the dual role of γ-PGA as a healing promoter and a potential protector of bacterial cells against antimicrobial agents. Methods: Multilayer dressing models were assembled in 96-well plates to simulate vertical stratification of antimicrobial layers4. Bacterial viability was assessed through relative OD₆₀₀ measurements following incubation with varying concentrations and spatial arrangements of cefiderocol, AgNPs, and γ-PGA. Data were analyzed using generalized linear modeling (GLM) with a gamma distribution and random forest regression to determine the relative importance of each factor in modulating bacterial survival. Results: γ-PGA concentration emerged as the dominant factor influencing bacterial viability, accounting for nearly 100% of variable importance in random forest analysis. Despite high antimicrobial pressure from cefiderocol and AgNPs, bacterial viability stabilized at approximately 40% in the presence of γ-PGA. The vertical positioning of γ-PGA significantly impacted survival; direct physical contact between the polymer and bacteria, particularly at high concentrations, enhanced bacterial persistence in P. aeruginosa and E. coli. Cefiderocol showed strain-specific potency, while AgNPs provided consistent growth inhibition. Conclusions: γ-PGA plays a paradoxical role in wound care by providing moisture retention while simultaneously acting as a cytoprotective agent that reduces antimicrobial efficacy, likely by facilitating biofilm formation. These findings underscore the necessity of optimizing the spatial layering and concentration of biopolymers in advanced dressings. Strategic design is crucial to balance regenerative benefits with maximal antimicrobial control to improve clinical outcomes in chronic wound management. Full article

Plant-based fermented foods are increasingly promoted for glycemic control, yet their mechanisms and clinical impact remain incompletely defined. This narrative review synthesizes mechanistic, preclinical, and human data for key matrices—kimchi and other fermented vegetables, tempeh/miso/natto, and related legume ferments, kombucha and fermented teas, plant-based kefir, and cereal/pulse sourdoughs. Across these systems, microbial β-glucosidases, esterases, tannases, and phenolic-acid decarboxylases remodel polyphenols toward more bioaccessible aglycones and phenolic acids, while lactic and acetic fermentations generate organic acids, exopolysaccharides, bacterial cellulose, γ-polyglutamic acid, γ-aminobutyric acid, and bioactive peptides. We map these postbiotic signatures onto proximal mechanisms—α-amylase/α-glucosidase inhibition, viscosity-driven slowing of starch digestion, gastric emptying and incretin signaling, intestinal-barrier reinforcement, and microbiota-dependent short-chain–fatty-acid and bile-acid pathways—and their downstream effects on AMPK/Nrf2 signaling and the gut–liver axis. Animal models consistently show improved glucose tolerance, insulin sensitivity, and hepatic steatosis under fermented vs. non-fermented diets. In humans, however, glycemic effects are modest and highly context-dependent: The most robust signal is early postprandial attenuation with γ-PGA-rich natto, strongly acidified or low-glycemic sourdough breads, and selected kombucha formulations, particularly in individuals with impaired glucose regulation. We identify major sources of heterogeneity (starters, process parameters, substrates, background diet) and safety considerations (sodium, ethanol, gastrointestinal symptoms) and propose minimum reporting standards and trial designs integrating metabolomics, microbiome, and host-omics. Overall, plant-based ferments appear best positioned as adjuncts within cardiometabolic dietary patterns and as candidates for “purpose-built” postbiotic products targeting early glycemic excursions and broader metabolic risk. Full article

In response to the limitations of hyaluronic acid (HA)—such as its high cost, short durability, and instability—in anti-aging aesthetic applications, this study developed a novel injectable micelle system, with a triple network structure. It is the particle size of approximately 400 nm and the elevated potential that enhance the crosslinking density and mechanical strength of the hydrogel. Importantly, following ultrafiltration and purification processes, the material’s hemolysis rate measured by spectrophotometry was only 3.25%, and endotoxin levels measured by the LAL assay were less than 0.5 EU/mL (test conditions: 37 °C, pH = 7, detection limit: 0.125 EU/mL). Building on this safe and stable material platform, we further designed an antibacterial wound dressing by functionalizing γ-PGA with penicillin or benzalkonium chloride. It reduced the cellular activity of Staphylococcus aureus by 78.9% and 84.2%, respectively. The outstanding safety profile, combined with customizable functionality, positions this γ-PGA-based platform as a promising multifunctional biomaterial meeting practical standards for both aesthetic medicine and wound care applications. Full article

Poly-γ-glutamic acid (γ-PGA), also known as polyglutamate, is a naturally derived polymer produced by Bacillus species that has demonstrated antiviral properties. Growing evidence from preclinical and clinical studies supports its therapeutic potential against various viral infections, highlighting both effective antiviral activity and a favorable safety profile. This review emphasizes current findings on the antiviral mechanisms of γ-PGA, including its ability to interfere with viral entry and to activate serial immune signaling pathways, with additional insights from structural biology. Collectively, γ-PGA represents a promising biomaterial for the development of future broad-spectrum antiviral strategies and applications. Full article

This study evaluated the influence of gamma-polyglutamic acid (γ-PGA) on the heavy metal sorption efficiency of three edible mushroom species—Pleurotus ostreatus, Agaricus bisporus, and Boletus edulis—exposed to cadmium (Cd), lead (Pb), and their mixtures (in a 1:1 ratio). The experiment presented an innovative approach—combining the natural sorption properties of mushrooms with the addition of γ-PGA, which has strong chelating properties. Sorption assays were performed using escalating γ-PGA concentrations (1, 2, and 5 mL to 250 mL of liquid medium), with data analyzed via generalized linear models employing a gamma distribution and a log link function. Results revealed that sorption efficiency was highest at the lowest γ-PGA concentration and decreased significantly with increasing γ-PGA levels across all species and metal treatments. Notably, P. ostreatus and A. bisporus demonstrated superior and more stable sorption capacities relative to B. edulis, which exhibited greater variability. These findings suggest that while edible mushrooms are effective biosorbents for heavy metals, higher γ-PGA concentrations may inhibit metal uptake by chelating metals in solution and reducing their bioavailability. Additionally, γ-PGA at 1 mM markedly enhanced antimicrobial activity against Salmonella enteritidis and Escherichia coli (with a 20% increase in growth inhibition zone compared to the control group) in mushroom cultures and when applied independently. This dual functionality underscores the potential of γ-PGA–mushroom systems for bioremediation and food safety applications, highlighting the need for the careful optimization of γ-PGA concentration to maximize biosorption efficacy and antimicrobial benefits. Full article

The study aim was to apply murine double minute 2 (MDM2)-siRNA to a biodegradable siRNA delivery vector, ternary complex, for treating colorectal cancer peritoneal dissemination. The ternary complex containing MDM2-siRNA (MDM2-siRNA complex) was constructed by mixing MDM2-siRNA, dendrigraft poly-L-lysine, and γ-polyglutamic acid. Cellular uptake of the ternary complex and suppressive effect on MDM2-mRNA were determined in a mouse colorectal cancer cell line. Tumor-growth inhibition by the MDM2-siRNA complex was evaluated in peritoneal dissemination model mice. The MDM2-siRNA complex, with an approximately 177 nm particle size and −35 mV ζ-potential, prevented degradation of the inner siRNA by RNase. In the in vitro study, the ternary complex was highly taken up by the cells, and 2 μg/mL of the MDM2-siRNA complex significantly decreased MDM2-mRNA to about 30% of control cells. Intraperitoneal administration in colorectal cancer peritoneal dissemination model mice showed little effect of the ternary complex containing scramble-siRNA on cancer growth in the peritoneal cavity. Conversely, the MDM2-siRNA complex significantly reduced peritoneal dissemination to less than 1/1000th of control mice and successfully prolonged survival time. In this study, we found that the biodegradable MDM2-siRNA complex had a suppressive effect on MDM2-mRNA in cancer cells and tumor growth of peritoneal dissemination. Full article

In this paper, a multifunctional polymer BT-PGA-TPE-HNPE was designed and synthesized by modifying γ-polyglutamic acid (γ-PGA) with biotin, the tetraphenylethylene derivative O-TPE-HNPE and an acid-sensitive imine bond. The polymer was used to fabricate paclitaxel (PTX)-loaded micelles. As expected, the BT-PGA-TPE-HNPE micelles demonstrated strong AIE characteristics, fluorescing yellow under normal conditions and blue in acidic settings. Moreover, the drug was specifically released under acidic conditions. In vitro and in vivo tumor suppression experiments showed that the micelles had enhanced antitumor activity with minimal systemic toxicity. The BT-PGA-TPE-HNPE micelles had wide application prospects in the fields of chemotherapy and bioimaging. Full article

Fermentation has been used for centuries to preserve food and to obtain products with new, attractive sensory characteristics. Fermented products are a source of dietary fiber, vitamins, bioactive compounds, and probiotic bacteria with health-promoting properties. This review provides a comprehensive overview of the effects of fermented fruits, vegetables, and legumes on metabolic disturbances characterizing metabolic syndrome (MetS). Furthermore, the chemical composition, microbial communities, and molecular mechanisms of action of fermented plant foods are discussed. Fermented fruits and vegetables, including table olives, caper fruits, and kimchi, contain polyphenols and probiotic bacteria, which are beneficial in terms of obesity and impaired glucose and lipid metabolism. Fermented legumes are a valuable source of bioactive peptides and isoflavone aglycones. Among fermented soybean products, natto stands out due to the presence of γ-polyglutamic acid, which improves glucose tolerance and the lipid profile, and nattokinase, an enzyme that acts as an angiotensin-converting enzyme inhibitor. Potential future studies focused on developing functional fermented foods and easy-to-use supplements based on fermented plant products are suggested. Full article

In this study, a Bacillus velezensis SDU strain capable of producing poly-γ-glutamate (γ-PGA) was newly identified from the rhizosphere soil of Baimiao taro. The strain is a glutamate-independent strain and can produce polyglutamic acid in a culture medium completely free of glutamate. The hydrolyzed product of the polyglutamic acid produced is D-glutamic acid. The molecular weight of γ-PGA, estimated via the Mark–Houwink equation, was 1390 kDa. Furthermore, the molecular weight measured by Waters gel permeation chromatography with multi-angle laser light scattering (GPC–MALLS) was 1167 kDa. The production of γ-PGA and its antioxidant and tyrosine inhibition properties were investigated. The γ-PGA production reached 23.1 g/L, and the productivity was 0.77 g L⁻¹ h⁻¹. Specifically, γ-PGA exhibited superoxide anion (·O₂⁻) radical scavenging activity and tyrosinase inhibitory activity. This study introduces a promising strain and a highly efficient application method for γ-PGA, which can be broadly utilized in the pharmaceutical, food, and cosmetic industries. Full article

This review offers an in-depth analysis of microbial γ-poly-glutamic acid (γ-PGA), highlighting its production, biosynthetic pathways, unique properties, and extensive applications in the food and health industries. γ-PGA is a naturally occurring biopolymer synthesized by various microorganisms, particularly species of Bacillus. The report delves into the challenges and advancements in cost-effective production strategies, addressing the economic constraints associated with large-scale γ-PGA synthesis. Its biocompatibility, biodegradability, and non-toxic nature make it a promising candidate for diverse industrial applications. γ-PGA’s exceptional water-holding capacity and humectant properties are key to its utility in the food industry. These features enable it to enhance the stability, viscosity, and shelf life of food products, making it a valuable ingredient in processed foods. The review highlights its ability to improve the textural quality of baked goods, stabilize emulsions, and act as a protective agent against staling. Beyond food applications, γ-PGA’s role in health and pharmaceuticals is equally significant. Its use as a drug delivery carrier, vaccine adjuvant, and biofilm inhibitor underscores its potential in advanced healthcare solutions. Full article