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Natural superabsorbent polymers (SAPs) were essential coating materials for developing slow-release fertilizers (SRFs) due to low cost and biodegradability. However, conventional natural SAPs were unsuitable for rice systems due to low stability and short slow-release period. Herein, a natural SAP with a semi-interpenetrating polymer network was prepared by poly (γ-glutamic acid) (PGlu), diatomite, and pullulan polysaccharide and combined with biochar to develop double-layer co-coated slow-release urea for rice systems. The results indicated that diatomite and pullulan modification significantly improved the slow-release capacity of SAP, with a significant increase in the average fertilizer 15N content of the soil profile by 37.9 ± 7.4% in 14–56 days. The improved slow-release capacity had significant benefits for the sustainability of the rice system, which increased plant N uptake by 17.2 ± 4.8%, decreased fertilizer N losses by 30.4 ± 7.2%, and increased rice grain yield by 9.88 ± 3.6%. More importantly, this natural SAP was fully degradable and its decomposition products are large amounts of small-molecule nutrients that could provide additional C, N, and Si to rice. Therefore, novel co-coated SRF may emerge as a greatly promising candidate for future intensive paddies. [ABSTRACT FROM AUTHOR]

Eugenol, as a natural antibacterial agent, has been widely studied for its inhibitory effect on the common food-borne pathogen Staphylococcus aureus (S. aureus). However, the widespread application of eugenol is still limited by its instability and volatility. Herein, γ-polyglutamic acid coated eugenol cationic liposomes (pGA-ECLPs) were successfully constructed by self-assembly with an average particle size of 170.7 nm and an encapsulation efficiency of 36.2%. The formation of pGA shell significantly improved the stability of liposomes, and the encapsulation efficiency of eugenol only decreased by 20.7% after 30 days of storage at 4 °C. On the other hand, the pGA layer can be hydrolyzed by S. aureus, achieving effective control of release through response to bacterial stimuli. The application experiments further confirmed that pGA-ECLPs effectively prolonged the antibacterial effect of eugenol in fresh chicken without causing obvious sensory effects on the food. The above results of this study provide an important reference for extending the action time of natural antibacterial substances and developing new stimuli-responsive antibacterial systems. [ABSTRACT FROM AUTHOR]

The exopolymer (ESPp) was obtained from Bacillus licheniformis IDN-EC, composed of a polyglutamic acid and polyglycerol phosphate chain O-substituted with αGal moieties (αGal/αGlcNH2 3:1 molar ratio) and with a 5000 Da molecular weight. The cytotoxicity activity of EPSp was determined by reducing the MTT (3-[4,5-dimethyl-thiazol-2-yl]-2,5-diphenyltetrazolium bromide) to formazan on HeLa cells. This EPS did not show cytotoxicity against the tested cell line. The ESPp presented great advantages as an antioxidant with free radical scavenging activities (1,1-diphenyl-2-picryl-hydrazyl radical (DPPH),hydroxyl radical (OH), and superoxide anion (O2−)) (65 ± 1.2%, 98.7 ± 1.9%, and 97 ± 1.7%), respectively. Moreover, EPSp increased the enzyme activity for catalase (CAT) and glutathione peroxidase (GSH-Px) in HeLa cells (CAT, 2.6 ± 0.24 U/mL; and GSH-Px, 0.75 ± 0.3 U/L). The presence of ESPp showed a significant protective effect against H2O2 in the cell line studied, showing great viability (91.8 ± 2.8, 89.9 ± 2.9, and 93.5 ± 3.6%). The EPSp presented good emulsifying activity, only for vegetable oils, olive oil (50 ± 2.1%) and sesame (72 ± 3%). Sesame was effective compared to commercials products, Triton X-100 (52.38 ± 1.6%), Tween 20 (14.29 ± 1.1%), and sodium dodecyl sulphate (SDS) (52.63 ± 1.6%). Furthermore, the EPS produced at 0.6 M has potential for environmental applications, such as the removal of hazardous materials by emulsification whilst resulting in positive health effects such as antioxidant activity and non-toxicity. EPSp is presented as a good exopolysaccharide for various applications. [ABSTRACT FROM AUTHOR]

The purpose of this study is to discover and excavate more key factors and signaling pathways that regulate the formation intensity of biofilms and to fully reveal the possible models affecting biofilm formation. By using gene homologous recombination and bioinformatics technology, a MutL protein-directed deletion mutant strain was successfully constructed. The growth status of the mutant strain was observed, and it was confirmed that, except for the change in cell morphology, there were no significant differences in growth and reproduction between the mutant strain and the wild-type strain. By using the induced biofilm formation technique, the significant decrease in biofilm formation in the MutL mutant strain was successfully verified. The plate confrontation test confirmed that the inhibitory ability of the mutant strain against rice blast fungus was not significantly different from that of the WT strain. The colonization ability of the mutant strain on rice stems was tested, and it was confirmed that the colonization ability of the mutant strain was significantly lower than that of the WT strain. In terms of the prevention and control effect of rice blast disease, the mutant strain showed a significant decrease. By using transcriptomic big data, the gene and pathway expression differences between the mutant strain and the WT strain during biofilm formation were analyzed. The analysis revealed no significant correlation with the previously reported spo0A and tapA-sipW-tasA pathways. The key factor capB of the polyglutamic acid signaling pathway, which affects the formation of the biological model, was found to have a significant decrease in expression. A mechanical hypothesis was proposed: MutL may participate in regulating the formation intensity of Bacillus biofilms by regulating the formation of glutamic acid to polyglutamic acid. [ABSTRACT FROM AUTHOR]

Polyglutamic acid (PGA), a biopolymer comprising repeating units of glutamic acid, has garnered significant attention owing to its versatile applications. In recent years, microbial production processes have emerged as promising methods for the large-scale synthesis of PGA, offering advantages such as sustainability, efficiency, and tailored molecular properties. Beyond its industrial applications, PGA exhibits unique properties that render it an attractive candidate for use in the cosmetic industry. The biocompatibility, water solubility, and film-forming characteristics of PGA make it an ideal ingredient for cosmetic formulations. This article explores the extensive potential cosmetic applications of PGA, highlighting its multifaceted role in skincare, haircare, and various beauty products. From moisturizing formulations to depigmentating agents and sunscreen products, PGA offers a wide array of benefits. Its ability to deeply hydrate the skin and hair makes it an ideal ingredient for moisturizers, conditioners, and hydrating masks. Moreover, PGA's depigmentating properties contribute to the reduction in hyperpigmentation and uneven skin tone, enhancing the overall complexion. As the demand for sustainable and bio-derived cosmetic ingredients escalates, comprehending the microbial production and cosmetic benefits of PGA becomes crucial for driving innovation in the cosmetic sector. [ABSTRACT FROM AUTHOR]

Background: Bacterial nanocellulose (BNC), a natural polymer material, gained significant popularity among researchers and industry. It has great potential in areas, such as textile manufacturing, fiber-based paper, and packaging products, food industry, biomedical materials, and advanced functional bionanocomposites. The main current fermentation methods for BNC involved static culture, as the agitated culture methods had lower raw material conversion rates and resulted in non-uniform product formation. Currently, studies have shown that the production of BNC can be enhanced by incorporating specific additives into the culture medium. These additives included organic acids or polysaccharides. γ-Polyglutamic acid (γ-PGA), known for its high polymerization, excellent biodegradability, and environmental friendliness, has found extensive application in various industries including daily chemicals, medicine, food, and agriculture. Results: In this particular study, 0.15 g/L of γ-PGA was incorporated as a medium additive to cultivate BNC under agitated culture conditions of 120 rpm and 30 ℃. The BNC production increased remarkably by 209% in the medium with 0.15 g/L γ-PGA and initial pH of 5.0 compared to that in the standard medium, and BNC production increased by 7.3% in the medium with 0.06 g/L γ-PGA. The addition of γ-PGA as a medium additive resulted in significant improvements in BNC production. Similarly, at initial pH levels of 4.0 and 6.0, the BNC production also increased by 39.3% and 102.3%, respectively. To assess the characteristics of the BNC products, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis were used. The average diameter of BNC fibers, which was prepared from the medium adding 0.15 g/L γ-PGA, was twice thicker than that of BNC fibers prepared from the control culture medium. That might be because that polyglutamic acid relieved the BNC synthesis from the shear stress from the agitation. Conclusions: This experiment held great significance as it explored the use of a novel medium additive, γ-PGA, to improve the production and the glucose conversion rate in BNC fermentation. And the BNC fibers became thicker, with better thermal stability, higher crystallinity, and higher degree of polymerization (DPv). These findings lay a solid foundation for future large-scale fermentation production of BNC using bioreactors. [ABSTRACT FROM AUTHOR]

Mineral plastics are a promising class of bio‐inspired materials that offer exceptional properties, like self‐heal ability, stretchability in the hydrogel state, and high hardness, toughness, transparency, and non‐flammability in the dry state along with reversible transformation into the hydrogel by addition of water. This enables easy reshape‐ability and recycling like the solubility in mild acids to subsequently form mineral plastics again by base addition. However, current mineral plastics rely on petrochemistry, are hardly biodegradable, and thus persistent in nature. This work presents the next generation of mineral plastics, which are bio‐based and biodegradable, making them a promising, new class of polymers for the development of environmentally friendly materials. Physically cross‐linked (poly)glutamic‐acid (PGlu)‐based mineral plastics are synthesized using various alcohol‐water mixtures, metal ion ratios and molecular weights. The rheological properties are easily adjusted using these parameters. The general procedure involves addition of equimolar solution of CaCl2 to PGlu in equal volumes followed by addition of iPrOH (iPrOH:H2O = 1:1) under vigorous stirring conditions. The ready biodegradability of PGlu/CaFe mineral plastic is confirmed in this study where the elements N, Ca, and Fe present in it tend to act as additional nutrients, supporting the growth of microorganisms and consequently, promoting the biodegradation process. [ABSTRACT FROM AUTHOR]

Hydrogels are three-dimensional networks of hydrophilic polymers. In general, these structures can be soft, elastic, porous and can absorb high quantities of water. Due to these characteristics, there is a growing interest in the use of hydrogels in diverse areas, from bioremediation to applications in the biomedical field. Although hydrogels can be elaborated with natural and synthetic polymers, natural polymers are attracting attention for their use in the biomedical and pharmaceutical fields. Alginate and γ-polyglutamic acid (γ-PGA) are microbial polymers, which show a great potential for hydrogel elaboration because of their biocompatibility that positioned them in emerging technologies, such as tissue engineering, microencapsulation, and soft robotics; these applications require specific characteristics of hydrogels in terms of their mechanical resistance, swelling capability, flexibility, softness, and stiffness. Thus, there is an emerging interest in the microbial production of alginates and γ-PGA, where it is possible to change their physicochemical and thermomechanical characteristics by the manipulation of the culture growth conditions of the microbial producers that can be oriented to specific applications. In this review, the chemical composition of biopolymers, hydrogel structure, the applications of hydrogels of alginates and γ-PGA, as well as their advantages and limitations are described; besides, the bacterial production of these polymers and the growth conditions that modify their chemical composition, are discussed.How to cite: Castillo T, Flores C, Salgado-Lugo H, et al. Alginate and γ-polyglutamic acid hydrogels: Microbial production strategies and biomedical applications. A review of recent literature. Electron J Biotechnol 2023;66. https://doi.org/10.1016/j.ejbt.2023.09.001.

Analytical methods for the early detection of the neurodegenerative biomarker for Parkinson's disease (PD), α-synuclein, are time-consuming and invasive, and require skilled personnel and sophisticated and expensive equipment. Thus, a pain-free, prompt and simple α-synuclein biosensor for detection in plasma is highly demanded. In this paper, an α-synuclein electrochemical biosensor based on hierarchical polyglutamic acid/ZnO nanowires decorated by gold nanoparticles, assembled as nanostars (NSs), for the determination of α-synuclein in human plasma is proposed. ZnO NSs were prepared by chemical bath deposition (CBD) and decorated with electrodeposited Au nanoparticles (Au NPs). Then, electro-polymerized glutamic acid was grown and functionalized with anti-α-synuclein. A synergistic enhancement of electrode sensitivity was observed when Au NPs were embedded into ZnO NSs. The analytical performance of the biosensor was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), using the Fe(II)(CN)64−/Fe(III)(CN)63− probe. The charge transfer resistance after α-synuclein recognition was found to be linear, with a concentration in the range of 0.5 pg·mL−1 to 10 pg·mL−1, a limit of detection of 0.08 pg·mL−1, and good reproducibility (5% variation) and stability (90%). The biosensor was also shown to reliably discriminate between healthy plasma and PD plasma. These results suggest that the proposed biosensor provides a rapid, quantitative and high-sensitivity result of the α-synuclein content in plasma, and represents a feasible tool capable of accelerating the early and non-invasive identification of Parkinson's disease. [ABSTRACT FROM AUTHOR]

Uterine leiomyoma (UL) is a prevalent benign tumor in women that frequently gives rise to a multitude of reproductive complications. The use of suicide gene therapy has been proposed as a highly promising method for treating UL. To achieve successful gene therapy, it is essential to develop carriers that can efficiently transport nucleic acids into targeted cells and tissues. The instability of polyplexes in blood and other biological fluids is a crucial factor to consider when using non-viral carriers. In this study, we present serum-resistant and cRGD-modified DNA complexes for targeted delivery genes to UL cells. Ternary polyplexes were formed by incorporating cystine-cross-linked polyglutamic acid modified with histidine residues. We employed two techniques in the production of cross-linked polyanionic coating: matrix polymerization and oxidative polycondensation. In this study, we investigated the physicochemical properties of ternary DNA complexes, including the size and zeta-potential of the nanoparticles. Additionally, we evaluated cellular uptake, toxicity levels, transfection efficiency and specificity in vitro. The study involved introducing the HSV-TK gene into primary UL cells as a form of suicide gene therapy modeling. We have effectively employed ternary peptide-based complexes for gene delivery into the UL organtypic model. By implementing in situ suicide gene therapy, the increase in apoptosis genes expression was detected, providing conclusive evidence of apoptosis occurring in the transfected UL tissues. The results of the study strongly suggest that the developed ternary polyplexes show potential as a valuable tool in the implementation of suicide gene therapy for UL. [ABSTRACT FROM AUTHOR]

Improving soil fertility is one of the key approaches for ecological restoration of the wind-sand area in northwest Liaoning Province. Taking wind-sand area in northwest Liaoning Province as test object, we conducted a fertilization experiment with treatments of inorganic fertilizer (nitrogen, phosphorus and potassium fertilizers), organic fertilizer, combined application of organic and inorganic fertilizers, and organic fertilizer combined with a biologically organic matrix (γ-polyglutamic acid), and no fertilizer as control. We measured soil organic matter content and extractable cations concentrations, vegetation coverage, and biomass under different fertilization treatments and determine the suitable fertilization mode. The results showed that compared to the control, inorganic fertilizer rapidly increased vegetation coverage and biomass, but high levels of inorganic fertilizer (150 kg N ⋅ hm-2) led to soil acidification and Ca2+ leaching. Organic fertilizer increased soil organic matter content, exchangeable K+, Ca2+, and Mg2+ contents, as well as coverage and biomass vegetation, especially combined with γ-polyglutamic acid. Overall, the combination of low levels of inorganic fertilizer (50 kg N ⋅ hm-2) and moderate levels of organic fertilizer (30000 kg ⋅ hm-2) was the best fertilization practice for the rapid and stable restoration of grassland in wind-sand area. Moreover, the extra addition of γ-polyglutamic acid (60 kg ⋅ hm-2) could effectively improve soil fertility. [ABSTRACT FROM AUTHOR]

Reservoirs after chemical flooding usually have residual chemicals, which can affect the driving effect of subsequent microbial drives. Among them, the effect of surfactants on the metabolites of oil-recovering bacteria is the most obvious. Therefore, this paper investigates the influence mechanism of sodium dodecyl sulfate (SDS) on the nature and structure of Extracellular Polymeric Substances (EPS) produced by metabolism of Enterobacter cloacae, through a variety of characterization to analysis the components and structure of EPS under SDS stress. The results showed that Enterobacter cloacae was identified as a glycolipid-producing strain, the main components of EPS were polysaccharides and proteins. The polysaccharide composition (%: w/w) was glucosamine, 37.2; glucose, 31.5; rhamnose, 26.3; xylose, 1.7; and unidentified sugar, 3.3; and the main component of proteins was polyglutamic acid. EPS under the stress of SDS showed an increase in the content of functional groups such as -C=O and -COOH and an increase in the cellular particle size, and production of EPS increased by 10.69 × 103 mg/L when the SDS concentration was 2.5 × 102 mg/L; 3D-EEM results showed that the components of all three types of EPS The 3D-EEM results showed that all three types of EPS fractions contained tryptophan and protein-like substances, humic acid-like substances were only distributed in the solubilized extracellular polymers (SL-EPS), and aromatic proteins were only present in the loosely bound type (LB-EPS) and tightly bound type (TB-EPS). In addition, the peaks representing humic-like substances showed a blue shift, indicating that SDS had the greatest effect on SL-EPS. This study provides a guidance for refining the mechanism of strain EPS response to reservoir residual surfactant SDS, and provides a more comprehensive and in-depth understanding of surfactant-protein interactions. [ABSTRACT FROM AUTHOR]

Polyglutamic acid (PGA), a biopolymer comprising repeating units of glutamic acid, has garnered significant attention owing to its versatile applications. In recent years, microbial production processes have emerged as promising methods for the large-scale synthesis of PGA, offering advantages such as sustainability, efficiency, and tailored molecular properties. Beyond its industrial applications, PGA exhibits unique properties that render it an attractive candidate for use in the cosmetic industry. The biocompatibility, water solubility, and film-forming characteristics of PGA make it an ideal ingredient for cosmetic formulations. This article explores the extensive potential cosmetic applications of PGA, highlighting its multifaceted role in skincare, haircare, and various beauty products. From moisturizing formulations to depigmentating agents and sunscreen products, PGA offers a wide array of benefits. Its ability to deeply hydrate the skin and hair makes it an ideal ingredient for moisturizers, conditioners, and hydrating masks. Moreover, PGA’s depigmentating properties contribute to the reduction in hyperpigmentation and uneven skin tone, enhancing the overall complexion. As the demand for sustainable and bio-derived cosmetic ingredients escalates, comprehending the microbial production and cosmetic benefits of PGA becomes crucial for driving innovation in the cosmetic sector.

γ-polyglutamic acid (γ-PGA) is a biomarker that can be directly obtained by microbial fermentation. Poly(amino acid) superabsorbent polymers (SAPs) were prepared with purified γ-PGA as raw material and ethylene glycol diglycidyl ether (EGDGE) as a cross-linking agent. However, γ-PGA fermentation broth has a high viscosity, requires complex extraction and separation processes, and entails high energy consumption, resulting in the high cost of poly (amino acid) SAPs. Therefore, the coupling fermentation processes of glutamate polyglutamic acid, the process of using glutamate fermentation broth instead of pure glutamate powder for fermentation, and the process of treating the fermentation broth under conditions of centrifugation, UV irradiation, and high temperature, were studied. The results showed that the yield of γ-PGA after centrifugation decreased by 5%, but it did not affect the synthesis of hydrogels, and the addition of γ-PGA fermentation broth had a significant effect on the performance of γ-PGA-co-PASP SAPs. The proposed method not only helps avoid the separation of complex γ-PGA fermentation broth and reduces the cost, but it also helps improve the performance of the super-absorbent resin, which has great application potential. [ABSTRACT FROM AUTHOR]

The vase life of cut lilies is short. Improving the vase life is very important to keep this kind of cut flower fresh by using exogenous improvers. The aim of this study was to elucidate the effectiveness of polyglutamic acid (PGA) on the vase life of cut lilies, in order to introduce a new vase life improver for cut lilies. The results demonstrated that PGA significantly strengthened the antioxidant capacity by enhancing the antioxidant activities (superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, glutathione peroxidase and glutathione S-transferase) and the antioxidant contents (total phenolics, total flavonoids, total anthocyanin and vitamin C), which further decreased the electrolyte leakage and the malondialdehyde and hydrogen peroxide contents. Meanwhile, the PGA significantly maintained the water balance by decreasing the water saturation deficit and increasing the relative water content and the soluble sugar and proline contents, as well as the average fresh weight change rate and average water balance value of the cut flower. Besides, the PGA significantly decreased the wilted flower numbers and increased the open flower numbers, flower diameter and the vase life of lily cut flower. The above findings provided useful information for the potential application of PGA as a new vase life improver for cut lilies. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of microparticle polyglutamic acid(γ -PGA) on cotton plant growth and rhizosphere soil microorganisms, and to determine the reasonable combined application dose. In this study, using a pot experiment of cotton, five treatments(P1(4.5 g of particulate γ -PGA combined with 1 g of chemical fertilizer), P2(3 g of particulate γ -PGA combined with 1 g of chemical fertilizer), P3(1.5 g of particulate γ -PGA combined with 1 g of chemical fertilizer), N(1 g of chemical fertilizer), and CK(no fertilization)) were set, the effects of particulate polyglutamic acid(γ-PGA) on growth of cotton plants and soil microbial community structure by analyzing cotton agronomic traits and high-throughput sequencing technology. The results showed that the agronomic traits of cotton in the treatments of particulate γ-PGA combined with chemical fertilizer were superior to those in the treatments of chemical fertilizer alone or no fertilizer, and 1.5 g of particulate γ-PGA combined with chemical fertilizer had the best effect. The contents of total potassium, ammonium nitrogen, and available phosphorus in the soil under particulate γ -PGA combined with chemical fertilizer were higher than those in the soil under chemical fertilizer alone or no fertilizer during the growth period of cotton. The contents of soil total potassium, ammonium nitrogen, available phosphorus, and available potassium remained high after harvest. High-throughput sequencing results showed that particulate γ -PGA combined with chemical fertilizer caused a reduction in microbial richness and diversity, but improved the microbial community structure. The relative abundance of Proteobacteria, Ascomycota and Mortierellomycota showed a downward trend after harvest, while the relative abundance of Actinobacteria, Acidobacteria and Basidiomycota showed an upward trend. Compared with chemical fertilizer alone and the control of water, most of the bacterial phyla still maintained high relative abundance. According to the redundancy analysis(RDA), the dominant phyla of soil microorganisms were affected by multiple key factors, including total phosphorus, total potassium, available phosphorus, available potassium, pH, and organic matter content. The effects of these key factors on the dominant phyla of soil microorganisms may vary with time. Particulate γ-PGA combined with chemical fertilizer could promote the growth and development of cotton. Although it reduced the overall richness and diversity of bacterial and fungal communities, the species of microbial communities were relatively concentrated in some beneficial bacteria which could still maintain a high relative abundance after cotton harvest, improve soil quality, and maintain high soil biological activity, which was conducive to agricultural production. [ABSTRACT FROM AUTHOR]

Safe and effective T cell vaccines are needed for the treatment or prevention of cancers as well as infectious agents where vaccines for neutralizing antibodies have performed poorly. Recent research highlights an important role for tissue-resident memory T cells (TRM cells) in protective immunity and the role of a subset of dendritic cells that are capable of cross-priming for the induction of TRM cells. However, efficient vaccine technologies that operate through cross-priming and induce robust CD8+ T cell responses are lacking. We developed a platform technology by genetically engineering the bovine papillomavirus L1 major capsid protein to insert a polyglutamic acid/cysteine motif in place of wild-type amino acids in the HI loop. Virus-like particles (VLPs) are formed by self-assembly in insect cells infected with a recombinant baculovirus. Polyarginine/cysteine-tagged antigens are linked to the VLP by a reversible disulfide bond. The VLP possesses self-adjuvanting properties due to the immunostimulatory activity of papillomavirus VLPs. Polyionic VLP vaccines induce robust CD8+ T cell responses in peripheral blood and tumor tissues. A prostate cancer polyionic VLP vaccine was more efficacious than other vaccines and immunotherapies for the treatment of prostate cancer in a physiologically relevant murine model and successfully treated more advanced diseases than the less efficacious technologies. The immunogenicity of polyionic VLP vaccines is dependent on particle size, reversible linkage of the antigen to the VLP, and an interferon type 1 and Toll-like receptor (TLR)3/7-dependent mechanism. [ABSTRACT FROM AUTHOR]

Improper fertilization has become an essential factor limiting peanut yield and quality improvement. To improve peanut yield and quality, the effects of different fertilizer additives on peanut growth and yield were investigated. In this work, the effects of four fertilizer additives produced by microorganisms (CL, T6, T4, and P1) on peanut growth and yield were evaluated through pot and field trials. The results indicated that all fertilizer additives significantly increased the branch number and biomass of peanuts compared to the control. Additionally, T6 and CL treatments led to significantly higher peanut yields in the field. The aboveground nitrogen concentration of peanuts treated with CL and T6 was also significantly higher than that of the control, while T4 treatment did not show a significant difference. Overall, CL and T6 had the best positive effect on the growth of peanuts. The potential application values of CL and T6 in peanuts showed that fertilizer additives produced by microorganisms could be used as effective measures to achieve highly efficient production in agriculture. [ABSTRACT FROM AUTHOR]

Polyglutamic acid (PGA), a protein in the mucilage of PGA-producing Bacillus spp., has expected applications in medical and biotechnological industries. Although the Bacillaceae family contains over 100 genera, research on bacterial PGA has exclusively focused on the genus Bacillus, especially B. subtilis var. natto and B. licheniformis. In the present study, indigenous Bacillaceae family strains were isolated from withered leaves and soil samples and screened for PGA production. As a result of the screening, the strain 8h was found to produce a mucilage possessing greater viscosity than PGA of B. subtilis var. natto (natto PGA). Biochemical analyses revealed that the 8h mucilage contains 63% protein and 37% polysaccharide, while mucilage of B. subtilis var. natto is composed of 61% protein and 39% polysaccharide. The most plentiful amino acid in 8h mucilage protein was glutamate (43%, mol/mol), which is similar to that of natto PGA, suggesting that it possesses characteristics of PGA. Although natto mucilage contains fructan, glucan was found as the polysaccharide of 8h mucilage. While phylogenetic studies indicated that the strain 8h belongs to Peribacillus simplex, the yield of the viscous mucilage by strain 8h was significantly higher than P. simplex type strain, suggesting that 8h is a mucilage-overproducing strain of P. simplex. Interestingly, 8h mucilage protein was found to contain more hydrophobic amino acid residues than natto PGA, suggesting that its amphiphilicity is suitable as a drug carrier and adjuvant. The present study is the first report of viscous mucilage and PGA-like protein produced by the genus Peribacillus. [ABSTRACT FROM AUTHOR]

Purpose: Development of new binding gels for rapid and simultaneous quantification of bioavailability concentrations of various heavy metals in soils by diffusive gradients in thin film technique. Methods: Four binding gels including zinc-aluminum hydrogel (ZnAl-LDH), ethylenediaminetetraacetic acid intercalated zinc-aluminum hydrogel (ZnAl-EDTA-LDHs), polyglutamic acid (PGA), and polyglutamic acid–sodium alginate resin (SA-PGA) were prepared and used for the simultaneous measurement of Cr, Ni, Cu, Cd, and Pb. Results: The adsorption process reached equilibrium in 2 h, which could be considered a pseudo-second-order reaction. Three mol L−1 nitric acid was the best eluent with elution efficiency over 91% for the five heavy metals. Then, SA-PGA gel was assembled into DGT device (SA-PGA-DGT). Its performance was virtually unaffected by pH (5–9), ionic strength (1–50 mM), and soil properties with adsorption capacities 5.02 μg cm−2, 11.38 μg cm−2, 8.16 μg cm−2, 17.11 μg cm−2, and 89.43 μg cm−2 for Cr, Ni, Cu, Cd, and Pb, respectively. A good linear correlation was observed between the concentrations of Cr, Ni, Cu, Cd, and Pb determined by SA-PGA-DGT in soil samples from Tanggu District in China and the exchangeable contents of the five metals determined by the Tessier method, with R values of 0.64, 0.63, 0.59, 0.72, and 0.64 (p < 0.01). Conclusion: SA-PGA gel exhibited the best adsorption properties among the four gels. SA-PGA-DGT can be used as a reliable tool for rapid and simultaneous quantification of bioavailability concentrations of multiple heavy metals. [ABSTRACT FROM AUTHOR]

[Display omitted] • Aerogel Beads had higher adsorption capacity in comparison to monolithic aerogels. • The aerogels could be used effectively up to 20 times. • Coordination bonding and electrostatic interactions were the main adsorption mechanisms. Heavy metals pose a significant threat to human health and ecological security due to their high toxicity, mobility, and persistence in the environment. Herein, the synthesis of a novel cellulose nanofiber-based aerogel using non-toxic biopolymers such as sodium alginate and polyglutamic acid to eradicate lead, zinc, and copper from water is described. The physical characterisation and the adsorption performance of the aerogels were evaluated in both monolithic and bead configurations. The study revealed superior adsorption performance for the aerogel beads compared to the monolithic configuration. The aerogel beads achieved a maximum adsorption capacity of 171.7 mg/g, 100.0 mg/g, and 142.0 mg/g for lead, zinc, and copper respectively. The aerogel beads exhibited a higher specific surface area compared to the monolithic aerogels. The presence of functional groups including carboxyl, amino, and hydroxyl groups on the aerogels likely facilitated the adsorption through coordinate bond formation and electrostatic interactions. Density Functional Theory calculations supported the role of oxygen and nitrogen containing groups on the aerogel in capturing heavy metal ions. The aerogels displayed a remarkable regeneration ability and were reused 20 times, without any significant reduction in the adsorption performance indicating its potential as a sustainable adsorbent for heavy metals removal from water. [ABSTRACT FROM AUTHOR]

Bone sialoprotein (BSP) is a multi-functional extracellular matrix (ECM) protein associated with mineralized tissues, particularly bone and cementum. The amino acid sequence of BSP includes three evolutionarily conserved sequences which contribute to functions of the protein: an N-terminal collagen-binding domain, polyglutamic acid (polyE) sequences involved in hydroxyapatite nucleation and crystal growth, and a C-terminal arginine-glycine-aspartic acid (RGD) integrin-binding domain. BSP promotes attachment and differentiation of osteogenic and osteoclastic cells. Genetic ablation of BSP in mice results in skeletal and dental developmental defects and impaired bone healing in both appendicular bone and alveolar bone of the jaw. Several studies demonstrated positive effects of BSP on bone healing in rodent models, though other experiments show negligible results. Native (harvested from rat bones) BSP cross-linked to collagen induced slight improvements in calvarial bone healing in rats. Recombinant BSP and collagen delivered in a polylactide (PLA) cylinder improved bone defect healing in rat femurs. Both native and recombinant BSP delivered in a collagen gel improved alveolar bone healing in wild-type and BSP-deficient mice. These advances suggest BSP is a new player in bone healing that has potential to be an alternative or complimentary to other bioactive factors. Future studies are necessary to understand mechanisms of how BSP influences bone healing and optimize delivery and dose in different types of bone defects and injuries. [ABSTRACT FROM AUTHOR]

Vascularization of bone grafts is vital for graft integration and bone repair, however non-autologous graft sources have limited potential to induce angiogenesis. Accordingly, intensive research has focused on functionalizing non-autologous materials with angiogenic factors. In the current study we evaluated a method for coupling an angiogenic peptide to the surface of two clinically-relevant graft materials, anorganic bovine bone (ABB) and synthetic hydroxyapatite (HA). Specifically, the VEGF-derived QK peptide was synthesized with a heptaglutamate (E7) domain, a motif that has strong affinity for calcium phosphate graft materials. Compared with unmodified QK, a 4-6 fold enrichment was observed in the binding of E7-modified QK (E7-QK) to ABB and HA. The E7-QK peptide was then assessed for its capacity to stimulate angiogenic cell behaviors. Human umbilical vein endothelial cells (HUVECs) were treated with solutions of either QK or E7-QK, and it was found that QK and E7-QK elicited equivalent levels of cell migration, tubule formation and activation of the Akt and ERK signaling pathways. These data confirmed that the inherent bioactivity of the QK sequence was not diminished by the addition of the E7 domain. We further verified that the activity of E7-QK was retained following peptide binding to the graft surface. HA disks were coated with QK or E7-QK, and then HUVECs were seeded onto the disks. Consistent with the increased amount of E7-QK bound to HA, relative to QK, markedly greater activation of Akt and ERK 1/2 was observed in cells exposed to the E7-QK-coated disks. Taken together, these results suggest that the E7 domain can be leveraged to concentrate angiogenic peptides on graft materials, facilitating delivery of higher peptide concentrations within the graft site. The ability to endow diverse graft materials with angiogenic potential holds promise for augmenting the regenerative capacity of non-autologous bone grafts.

Nanobiopolymers such as chitosan, gelatin, hyaluronic acid, polyglutamic acid, lipids, peptides, exosomes, etc., delivery systems have prospects to help overwhelmed physiological difficulties allied with the delivery of siRNA drugs to solid tumors, including breast cancer cells. Nanobiopolymers have favorable stimuli-responsive properties and therefore can be utilized to improve siRNA delivery platforms to undruggable MDR metastatic cancer cells. These biopolymeric siRNA drugs can shield drugs from pH degradation, extracellular trafficking, and nontargeted binding sites and are consequently suitable for drug internalization in a controlled-release fashion. In this review, the utilization of numerous biopolymeric compounds such as siRNA drug delivery systems for MDR solid tumors, including breast cancers, will be discussed. [ABSTRACT FROM AUTHOR]

Recently, human hair keratin has been widely studied and applied in clinical fields due to its good histocompatibility, biocompatibility, and biodegradability. However, the regenerated keratin from human hair cannot be electrospun alone because of its low molecular weight. Herein, gamma polyglutamic acid (γ-PGA) was first selected to fabricate smooth and uniform γ-PGA/keratin composite scaffolds with excellent biocompatibility and biodegradability by electrospinning technology and a chemical cross-linking method in this study. The effect of electrospinning parameters on the structure and morphology, the mechanism of chemical cross-linking, biocompatibility in vitro cell culture experiments, and biodegradability in phosphate-buffered saline buffer solution and trypsin solution of the γ-PGA/keratin electrospun nanofibrous scaffolds (ENS) was studied. The results show that the cross-linked γ-PGA/keratin ENSs had excellent water stability and biodegradability. The γ-PGA/keratin ENSs showed better biocompatibility in promoting cell adhesion and cell growth compared with the γ-PGA ENSs. It is expected that γ-PGA/keratin ENSs will be easily and significantly used in tissue engineering to repair or regenerate materials. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chinese Institute of Food Science & Technology / Zhongguo Shipin Xuebao is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polyaspartic acid is considered a green agent for the treatment of circulating cooling water. However, its chemosynthetic process is not green, as it requires significant amounts of energy and causes water pollution. In this work, we identified an analog of polyaspartic acid, namely polyglutamic acid (γ-PGA), which could be directly produced by Bacillus spp., and we explored its performance and scale inhibition mechanism as a scale inhibitor. We found that γ-PGA secreted by B. megaterium with a molecular weight of ~ 70 kDa showed poor scale inhibition, while the γ-PGA secreted by B. licheniformis with a molecular weight of ~ 15 kDa had a 26.87% higher efficiency compared to commercially available polyaspartic acid. The scale inhibition mechanism was explored using the γ-PGA material secreted by B. licheniformis. Fourier transform spectrometer, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy analysis demonstrated that the scale inhibition performance of γ-PGA was due to the combination of its functional groups and Ca2+, which affected the growth process of CaCO3 and inhibited the formation of CaCO3. This study provided deeper insight into scale inhibition performance related to the scale inhibition mechanism. [ABSTRACT FROM AUTHOR]

Glutamate wastewater has a high yield in the world and is difficult to be treated due to its high acidity, high COD (chemical oxygen demand, reflecting the pollution degree of reduced substances in the water) and high ammonia nitrogen characteristics. In this study, Bacillus licheniformis M 2020051 was used to treat organic wastewater to ferment polyglutamic acid, which reduced the pollution of industrial wastewater and produced polyglutamic acid at a low cost. Firstly, a strain with high salt tolerance and high polyglutamic acid production was isolated from saline soil, and the mechanism of salt tolerance and polyglutamic acid production were also analyzed. Then Single-factor experiment and Response surface methodology (RSM) were used to determine the appropriate fermentation conditions to achieve maximum γ-polyglutamic acid production. After optimization, the yield of polyglutamic acid was increased to 6.91 g·L−1 by shaking fermentation, an increase of 7.13%. Finally, the agronomic experiments were carried out, and the results showed that γ-polyglutamic acid could significantly increase the germination rate of corn seeds and the growth of rapeseed. These studies will lay the foundation for reducing industrial wastewater pollution and exploring the production model of γ-polyglutamic acid. [ABSTRACT FROM AUTHOR]

γ-PGA-PAE nanomaterials were prepared by spontaneous assembly of γ-PGA through condensation reaction, and preparation process of nanomaterials was optimized. HCPT/PGA-PAE nanospheres were prepared by using 10-hydroxycamptothecin as embedding drug, and the nanospheres prepared under the optimal conditions were characterized. The results showed that γ-PGA-PAE nanomaterials were successfully prepared with spherical shape and uniform distribution. HCPT/PGA-PAE nanospheres had high encapsulation rate and drug loading. The optimization of the processing conditions of nanomaterials by response surface method (RSM) is a feasible method to improve the utilization rate of γ-PGA, which provides a theoretical basis for the synthesis of nanomaterials in the future. [ABSTRACT FROM AUTHOR]

This present work is aimed to screen the PGA-producing Bacillus spp. from naturally fermented soybean foods of Arunachal Pradesh in India and to characterize the poly-glutamic acid (PGA) extracted from Bacillus spp. A total of 50 isolates were screened for high stickiness from 165 bacterial isolates isolated from 34 samples viz., grep chhurpi, peha/paeha, peron namsing, and peruñyaan. Based on 16S rRNA gene sequence analysis, 50 isolates were identified as Bacillus spp. Viscosity of 50 species of Bacillus were measured, out of which 7 species of Bacillus showing ≥0.03 Pa.s (30 cP) of viscosity were selected viz., Bacillus velezensis GC1-42, B. siamensis GC4-36, B. subtilis PH3-21, B. subtilis PN1-14, B. subtilis PH6-29, B. tequilensis PN9-22, and B. safensis subsp. safensis PY1-19 for PGA production. Amino acid analysis of PGA extracted from seven species of Bacillus showed high molecular weight (>600 kDa). B. safensis subsp. safensis PY1-19, isolated from peruñyaan, showed 78.9% of glutamic acid, antagonistic properties against pathogenic bacteria and had the ability to produce phytase with no hemolytic activity. Hence, this strain was selected as a potential starter to prepare peruñyaan at laboratory, and the final product showed high stickiness and viscosity with production of PGA of around 11 g/L. [ABSTRACT FROM AUTHOR]

Binders play a very important part in electrodes, as they closely bind active materials, conductive agents, and current collectors together. The application of binders is critical to the electrochemical performance of Li-S batteries. Herein, a series of studies on sulfur cathodes with different binders is carried out. Compared to traditional polyvinylidene fluoride, γ-polyglutamic acid (γ-PGA) is rich in polar functional groups (amino and carboxyl groups), and the shuttle effect of lithium polysulfide can thereby be inhibited due to the secondary bond between the functional groups and polysulfide. Furthermore, the integrity of the cathode during electrochemical processes can be maintained with a γ-PGA binder. After assembly with a Li anode, a capacity retention of 62.5% is maintained after 100 cycles, which is much higher than that of batteries with traditional binders such as polyvinylidene fluoride (53.9%), polyvinylpyrrolidone (52.8%), sodium carboxymethylcellulose (40.7%), and polyacrylonitrile (51.5%). [ABSTRACT FROM AUTHOR]

BACKGROUND: Sucrose is an naturally abundant and easily fermentable feedstock for various biochemical production processes. By now, several sucrose utilization pathways have been identified and characterized. Among them, the pathway consists of sucrose permease and sucrose phosphorylase is an energy-conserving sucrose utilization pathway because it consumes less ATP when comparing to other known pathways. Bacillus amyloliquefaciens NK-1 strain can use sucrose as the feedstock to produce poly-γ-glutamic acid (γ-PGA), a highly valuable biopolymer. The native sucrose utilization pathway in NK-1 strain consists of phosphoenolpyruvate-dependent phosphotransferase system and sucrose-6-P hydrolase and consumes more ATP than the energy-conserving sucrose utilization pathway. RESULTS: In this study, the native sucrose utilization pathway in NK-1 was firstly deleted and generated the B. amyloliquefaciens 3Δ strain. Then four combination of heterologous energy-conserving sucrose utilization pathways were constructed and introduced into the 3Δ strain. Results demonstrated that the combination of cscB (encodes sucrose permease) from Escherichia coli and sucP (encodes sucrose phosphorylase) from Bifidobacterium adolescentis showed the highest sucrose metabolic efficiency. The corresponding mutant consumed 49.4% more sucrose and produced 38.5% more γ-PGA than the NK-1 strain under the same fermentation conditions. CONCLUSIONS: To our best knowledge, this is the first report concerning the enhancement of the target product production by introducing the heterologous energy-conserving sucrose utilization pathways. Such a strategy can be easily extended to other microorganism hosts for reinforced biochemical production using sucrose as substrate.

BACKGROUND: Poly-γ-glutamic acid (γ-PGA) is a valuable polymer with glutamate as its sole precursor. Enhancement of the intracellular glutamate synthesis is a very important strategy for the improvement of γ-PGA production, especially for those glutamate-independent γ-PGA producing strains. Corynebacterium glutamicum has long been used for industrial glutamate production and it exhibits some unique features for glutamate synthesis; therefore introduction of these metabolic characters into the γ-PGA producing strain might lead to increased intracellular glutamate availability, and thus ultimate γ-PGA production. RESULTS: In this study, the unique glutamate synthesis features from C. glutamicum was introduced into the glutamate-independent γ-PGA producing Bacillus amyloliquefaciens NK-1 strain. After introducing the energy-saving NADPH-dependent glutamate dehydrogenase (NADPH-GDH) pathway, the NK-1 (pHT315-gdh) strain showed slightly increase (by 9.1%) in γ-PGA production. Moreover, an optimized metabolic toggle switch for controlling the expression of ɑ-oxoglutarate dehydrogenase complex (ODHC) was introduced into the NK-1 strain, because it was previously shown that the ODHC in C. glutamicum was completely inhibited when glutamate was actively produced. The obtained NK-PO1 (pHT01-xylR) strain showed 66.2% higher γ-PGA production than the NK-1 strain. However, the further combination of these two strategies (introducing both NADPH-GDH pathway and the metabolic toggle switch) did not lead to further increase of γ-PGA production but rather the resultant γ-PGA production was even lower than that in the NK-1 strain. CONCLUSIONS: We proposed new metabolic engineering strategies to improve the γ-PGA production in B. amyloliquefaciens. The NK-1 (pHT315-gdh) strain with the introduction of NADPH-GDH pathway showed 9.1% improvement in γ-PGA production. The NK-PO1 (pHT01-xylR) strain with the introduction of a metabolic toggle switch for controlling the expression of ODHC showed 66.2% higher γ-PGA production than the NK-1 strain. This work proposed a new strategy for improving the target product in microbial cell factories.

Calcium has limited bioavailability owing to the formation of calcium phosphate deposits in the gastrointestinal tract. In this study, a polyglutamic acid (PGA)-Ca complex of calcium chelate was prepared using γ-PGA. The binding constant between γ-PGA and calcium was determined to be 6.50 ± 2.47 × 104 mol/L, where 3.6 units of glutamate was capable of binding one Ca2+. The structure of PGA-Ca was characterized, revealing that Ca2+ chelation promoted the aggregation of γ-PGA molecules, disrupting the network structure and forming a mineralized β-sheet-rich structure. In vitro digestion experiments demonstrated that PGA-Ca better maintained the soluble state of Ca2+ in the intestine compared with CaCl 2. Cell absorption experiments showed that PGA-Ca exhibited 20% higher permeability through Caco-2 cell monolayers than CaCl 2 , indicating its higher bioavailability. Notably, PGA-Ca demonstrated improved absorption in the presence of dietary inhibitors, such as oxalate, tannin, and phytate, which compete with Ca2+. Finally, the molecular mechanism underlying the promotion of calcium absorption by PGA-Ca was investigated using RNA sequencing. The results reveal that PGA-Ca enhanced Ca2+ active transport by upregulating CACNA2D3 and downregulating CBARP , while enhancing paracellular Ca2+ transport by downregulating JAM2. This comprehensive study highlights the potential of PGA-Ca as a highly beneficial calcium-delivery system. • The chelate binding mode and conformational changes of PGA-Ca were investigated. • PGA-Ca showed high solubility and stability in vitro digestion. • PGA-Ca enhanced calcium absorption in small intestinal epithelial cells. • The mechanism of active calcium absorption in Caco-2 promoted by PGA-Ca was studied. [ABSTRACT FROM AUTHOR]

Cryopreservation is highly desired for long-term maintenance of the viability of living biosamples, while effective cell cryopreservation still relies heavily on the addition of dimethyl sulfoxide (DMSO) and fetal bovine serum (FBS). However, the intrinsic toxicity of DMSO is still a bottleneck, which could not only cause the clinical side effect but also induce cell genetic variants. In the meantime, the addition of FBS may bring potentially the risk of pathogenic microorganism contamination. The liquid marbles (LMs), a novel biotechnology tool for cell cryopreservation, which not only have a small volume system that facilitated recovery, but the hydrophobic shell also resisted the harm to cells caused by adverse environments. Previous LM-based cell cryopreservation relied heavily on the addition of FBS. In this work, we introduced acidic polyaspartic acid and polyglutamic acid as cryoprotectants to construct LM systems. LMs could burst in an instant to facilitate and achieve ultrarapid recovery process, and the hydrophilic carboxyl groups of the cryoprotectants could form hydrogen bonds with water molecules and further inhibit ice growth/formation to protect cells from cryoinjuries. The L929 cells could be well cryopreserved by acidic polyamino acid-based LMs. This new biotechnology platform is expected to be widely used for cell cryopreservation, which has the potential to propel LMs for the preservation of various functional cells in the future. • The LM cryopreservation system was constructed by using acidic polyamino acids. • The acidic polyamino acid displayed a superior biocompatibility. • The preparation of LMs was easy, and the LMs could be recovered quickly. • The acidic polyamino acid-based LMs showed excellent cryopreservation efficiency. [ABSTRACT FROM AUTHOR]

Copyright of China Surfactant Detergent & Cosmetics (1001-1803) is the property of China Surfactant Detergent & Cosmetics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biostimulants can enhance horticultural crop production. However, their application in hydroponically grown lettuce is still limited, and information regarding their relative efficacy is lacking. A greenhouse trial was conducted to address this issue. Five nutrient solution treatments were evaluated on two lettuce cultivars: butterhead and red oak-leaf. The treatments included a half-strength modified Hoagland solution (Hs-H); a full-strength modified Hoagland solution (Fs-H); and Hs-H supplemented with 50 mg L−1 fulvic acid (FA), 334 mg L−1 seaweed extract (SE), or 5 mL L−1 gamma polyglutamic acid (PGA). The results indicated that the shoot biomass observed after biostimulant supplementation was significantly greater than or comparable to that observed with Fs-H. Nutrient solutions supplemented with SE and PGA led to a greater increase in the root biomass than that realized with Hs-H and Fs-H treatments. The Hs-H + FA treatment resulted in the lowest root-to-shoot ratio on a fresh weight basis among all treatments. The nitrate concentration in the shoot was significantly reduced following biostimulant supplementation compared to that realized with Fs-H and Hs-H treatments. Nutrient solutions supplemented with SE and PGA also decreased soluble sugar concentrations compared to that achieved using Hs-H and Fs-H treatments. FA and SE improved nutrient uptake for both cultivars, but PGA had a minimal effect on nutrient uptake. The two cultivars varied in their responses to biostimulant supplementation with regard to biomass, quality traits, and nutrient uptake. This study supports using fulvic acid and seaweed extract, rather than γ-PGA, in hydroponic lettuce production systems. [ABSTRACT FROM AUTHOR]