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The expansion of the use of induced resistance (IR) has been, and remains, an attractive prospect for the management of woody plants, but little research has occurred assessing the ability of elicitors to induce the root defenses of woody plants. Eastern white pine (Pinus strobus) was used as a model plant to assess IR elicitation. Containerized plants were treated with phosphite (Phi), chitosan, curdlan (a β-1,3- glucan polymer), or silicon (Si) on 2022 June 7. The soluble phenolic levels, tissue levels of major resin acids (abietic and neoabietic), as well as the activities of peroxidase (POX), chitinase (CHI), and β-1,3-glucanase (βGLU) of fine roots were compared across elicitor treatments and nontreated controls on June 10, June 14, and June 27. There were no changes post-treatment to soluble phenolics or resin acids at any sampling point, but chitosan treatment resulted in an increase in POX and CHI activities, while curdlan increased CHI activity on June 10. On June 14, curdlan-treated plants had significantly higher POX and CHI activities, while Phi-treated plants had significantly higher POX activity. By June 27, curdlan- and Phi-treated trees had significantly higher CHI activities. Our data suggest that chitosan, curdlan, and phosphite stimulate biochemical responses and potentially prime root systems to respond to subsequent stresses, but there appears to be variation between these elicitors regarding rapid versus longer lasting IR effects. [ABSTRACT FROM AUTHOR]

Background and Aims: This study aimed to prepare and characterize, as well as compare the potential of biopolymer-based hydrogels for topical administration of ornidazole, a commonly used drug against vaginal infections. Hydrogels were successfully prepared using curdlan (Crd), carboxymethyl curdlan (CMCrd), hydroxypropyl methyl cellulose (HPMC), and xanthan gum (XG) as biopolymers, which were used alone or blended. In addition, carboxymethylation of Crd, a natural polysaccharide polymer that is attractive in the pharmaceutical field, was carried out in-house. Methods: The structure of the synthesised CMCrd was analysed by Fourier-transform infrared spectroscopy(FT-IR). The physico-chemical, mechanical, and mucoadhesive properties of hydrogels were evaluated, then the drug release patterns from the hydrogels were examined in a simulated vaginal environment. Results: The hydrogels exhibited a uniform appearance and were pH-compatible with the vaginal environment. The viscosity, spreadability, and drug release characteristics were dependent on the polymer type and total amount of polymer present in the hydrogels. The texture profile analysis results indicated that all formulations exhibited appropriate mechanical characteristics (hardness, compressibility, cohesiveness, and elasticity) for vaginal administration, while also demonstrating mucoadhesive properties and good stability. Carboxymethylation improved mucoadhesion of Crd. Conclusion: The results obtained indicate that the hydrogels developed in this study can be considered promising candidates for the local treatment of vaginal infections. [ABSTRACT FROM AUTHOR]

To expand the scope of application of the insoluble polysaccharide curdlan (CUR), this study modified CUR with octenyl succinic anhydride (OSA) and evaluated the performance of the emulsion formed from the modified CUR derivative. Fourier transform infrared spectroscopy, differential scanning calorimetry, and X‐ray diffraction analysis showed that properties such as the molecular structure, crystallinity, and hydrophobicity of the OSA‐modified CUR (COSA) changed significantly compared with those of the original CUR, indicating that the hydroxyl group of CUR was successfully replaced by OSA. Subsequently, a stable oil‐in‐water emulsion system of COSA loaded with curcumin was established. The stability of the emulsions was evaluated by analyzing their microstructure, rheological properties, and curcumin retention. The digestion characteristics of the emulsions were evaluated by in vitro simulated digestion experiments, and the COSA emulsion had higher stability and was better able to improve the chemical stability of curcumin compared to CUR. The OSA grafting resulted in emulsions with higher curcumin release rates and antioxidant capacities. These results indicate that COSA has the potential to be used as an encapsulating material for lipophilic nutrient emulsions and provides theoretical support for expanding the applications of chemically modified CUR derivatives. [ABSTRACT FROM AUTHOR]

In this study, a novel active film was developed by employing ε‐polylysine (ε‐PL) as a filler in pullulan/curdlan (P/CD) composite film (P/CD/ε‐PL). The results showed that the structure of P/CD films was more uniform and denser compared to pullulan films, due to the good compatibility and intermolecular interaction between them. Among P/CD films, P/CD 6:1 film showed improved hydrophobicity, mechanical and barrier properties, and thermal stability, thereby selecting it for further use. Thereafter, the addition of ε‐PL further enhanced the structural and physicochemical properties of prepared P/CD/ε‐PL composite films, especially for P/CD/2.5%ε‐PL composite film. It exhibited improved ultraviolet barrier (about 80% at 200–400 nm), antibacterial activity (>90% against Staphylococcus aureus and Escherichia coli), and anti‐fog properties (clearly visible and transparent background). Furthermore, P/CD/2.5%ε‐PL composite film exerted its preservation effect on fresh‐cut peppers and kiwis during storage, delaying the softening, consumption of soluble solids, and deterioration. Therefore, the developed P/CD/2.5%ε‐PL composite film provided promising applications of active packing film. Practical Application: Fresh‐cut fruits and vegetables are prone to deteriorate during storage, and active packaging films play a crucial role in retaining their quality. This study was conducted to prepare a composite film by blending pullulan, curdlan, and ε‐PL and explore its structural, physicochemical, and functional properties, further verifying the preservation effect on fresh‐cut peppers and kiwis. Compared to polyethylene film, the P/CD/2.5%ε‐PL composite film delayed the softening, consumption of soluble solids, and deterioration of fresh‐cut peppers and kiwis during storage. It provides a new perspective on the preservation of fresh‐cut fruits and vegetables. [ABSTRACT FROM AUTHOR]

Curdlan's application is constrained by high gelation concentration, poor water solubility, and incompatibility with other polysaccharides. To address these limitations, this study investigated the effects of different concentrations (0.05–0.3%) of non-ionic polysaccharides (pullulan (PL), locust bean gum (LBG), guar gum (GG), and konjac gum (KGM)) on the heat-induced gelling properties of curdlan. PL with no branch showed 0.3% enhanced gel hardness. LBG with a small amount of galactose residue and KGM with an acetyl group had similar effects on hardness, while GG with a large amount of galactose residue slightly weakened the mixed gel. The rheological results showed that PL had little effect on curdlan, and LBG and KGM had a positive effect on curdlan unfolding, but 0.3% GG was significantly antagonistic to curdlan. The above results implied that non-ionic polysaccharides without side chains interacted weakly with the curdlan and hardly changed the properties of curdlan. Curdlan unfolding and stable suspension were favored if the structure contained galactose or acetyl side chains that interacted with curdlan through hydrogen bonding. These results suggested an effective way to modify curdlan by strengthening the interaction of curdlan with others and weakening the hydrogen bonding of curdlan to broaden its application in food colloids. [ABSTRACT FROM AUTHOR]

This study successfully developed edible films with excellent mechanical strength and notable water resistance, utilizing curdlan (CL) as the primary matrix and incorporating various plasticizers, including glycerol (GLY), ethylene glycol (EG), propylene glycol (PRO), xylitol (XY), sorbitol (SOR), and polyethylene glycol (PEG). A comprehensive suite of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), and tensile testing, were employed to evaluate the films' structural and mechanical properties. After incorporating PEG, the water sensitivity increased slightly, with a contact angle (CA) of 97.6°, and a water solubility (WS) of 18.75%. The inclusion of plasticizers altered the crystalline structure of the CL matrix, smoothing and flattening the film surface while reducing hydrogen-bonding interactions. These structural changes led to a more uniform distribution of amorphous chain segments and a decrease in glass transition temperatures. Among the tested plasticizers, GLY exhibited the highest compatibility with CL, resulting in the smoothest surface morphology and delivering the most effective plasticizing effect. The CL-GLY film showed a dramatic improvement in flexibility, with an elongation at break that was 5.2 times higher than that of the unplasticized film (increasing from 5.39% to 33.14%), indicating significant enhancement in extensibility. Overall, these findings highlight the potential of CL-GLY films as sustainable and effective materials for food packaging applications. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department 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.)

In this study, the upstream and downstream production processes of curdlan from Priestia megaterium were optimized to enhance its yield. Additionally, a novel extraction method was developed for curdlan recovery. Optimization studies were conducted using Central composite design (CCD). Curdlan yield improved from 0.15 g/L (unoptimized) to 0.46 g/L (3-fold increase) when fermentation was carried out in CCD-optimized media of (w/v) sucrose 20%, urea 0.1%, KH2PO4 0.02%, agitation speed 250 rpm. To further enhance curdlan yield during extraction, ultrasonication was incorporated as a novel step into the conventional method of acid/alkali-assisted curdlan recovery. A two-step optimization was chosen for extraction, namely, one-factor-at-a-time (OFAT) and CCD, wherein the optimized extraction parameters were determined to be 25 s sonication, 1 N NaOH, and 2 h solubilization time. The curdlan yield improved by 1.5-fold (0.70 g/L) post optimization, in comparison with unoptimized conventional extraction step. Finally, the biopolymer was validated through characterization by nuclear magnetic resonance (NMR) which showed characteristic curdlan spectra in the13C and1H NMR studies. To the best of our knowledge, this study represents the first documented report on curdlan extraction using this novel method of ultrasonication. [ABSTRACT FROM AUTHOR]

In this study, the inhibitory effect of an edible composite composed of coating water-soluble chitosan and curdlan on postharvest infection of cherry tomatoes by Botrytis cinerea and the underlying mechanism was investigated. The mycelial growth, minimum inhibitory concentration (MIC), spore germination and membrane permeability of B. cinerea were studied. The results showed that the composite coating had a significant inhibitory effect on the growth of B. cinerea. After treatment with the composite coating, the cell membrane was damaged, resulting in leakage of intracellular contents and hyphal shrinkage. Meanwhile, it significantly inhibited the expansion of B. cinerea lesions. The composite coating might inhibit B. cinerea mainly by affecting the cell wall and membrane. These results suggest that the water-soluble chitosan/curdlan edible composite coating can be used as an effective antimicrobial material in the storage and preservation of cherry tomatoes.

Objective: Hot air coupled with ultrasound and infrared irradiation were used for the drying of curdlan. The drying mechanism and quality change of curdlan were explored under the multi-physical fields, so as to developing the green drying technology of curdlan. Methods: Forced convective hot air alone, ultrasound-coupled forced convective hot air, infrared irradiation alone, and infrared-coupled forced convective hot air were used to dry curdlan. A mass transfer model considering temeprature change was constructed and the quality of the dried curdlan was comprehensively assessed. Results: Under the studied forced convective hot air drying conditions, it took around 40 min to dry the curdlan, and the required drying time was reduced to 36, 26 and 22 min for ultrasound-coupled hot air drying, infrared irradiation alone drying, and infrared-coupled hot air drying, respectively. The moisture transfer model coupled with the temperature change was able to accurately predict the change of the moisture content throughout drying. Under infrared drying coupled with convective hot air, the range of moisture effective diffusivity inside curdlan was 9.79×10−9 to 9.81×10−9 m2/s, and the surface mass transfer coefficient was 4.69×10−2 kg water/(m2·s), which were higher than those of the other treatment groups, followed by those under infrared irradiation alone drying, ultrasonic-coupled hot air drying, and hot air drying alone. Moreover, the gel strength, glucose content, the distribution of chemical functional groups on surface, crystal structure and thermal stability of curdlan samples dried by different methods were all similar. Conclusion: Taking all these results into consideration, infrared drying was regarded as an efficient method for drying curdlan compared to hot air drying and ultrasound-coupled hot air drying.

Endo-β-1,3-glucanase is a glycoside hydrolase (GH) that plays an essential role in the mineralization of β-glucan polysaccharides. In this study, the novel gene encoding an extracellular, non-modular GH16 endo-β-1,3-glucanase (GluH) from Hymenobacter siberiensis PAMC 29290 isolated from Arctic marine sediment was discovered through an in silico analysis of its whole genome sequence and subsequently overexpressed in Escherichia coli BL21. The 870-bp GluH gene encoded a protein featuring a single catalytic GH16 domain that shared over 61% sequence identity with uncharacterized endo-β-1,3-glucanases from diverse Hymenobacter species, as recorded in the National Center for Biotechnology Information database. The purified recombinant endo-β-1,3-glucanase (rGluH: 31.0 kDa) demonstrated peak activity on laminarin at pH 5.5 and 40°C, maintaining over 40% of its maximum endo-β-1,3-glucanase activity even at 25°C. rGluH preferentially hydrolyzed D-laminarioligosaccharides and β-1,3-linked polysaccharides, but did not degrade D-laminaribiose or structurally unrelated substrates, confirming its specificity as a true endo-β-1,3-glucanase without ancillary GH activities. The biodegradability of various substrate polymers by the enzyme was evaluated in the following sequence: laminarin > barley β-glucan > carboxymethyl-curdlan > curdlan > pachyman. Notably, the specific activity (253.1 U mg–1) and catalytic efficiency (kcat/Km: 105.72 mg–1 s–1 mL) of rGluH for laminarin closely matched its specific activity (250.2 U mg–1) and kcat/Km value (104.88 mg–1 s–1 mL) toward barley β-glucan. However, the kcat/Km value (9.86 mg–1 s–1 mL) of rGluH for insoluble curdlan was only about 9.3% of the value for laminarin, which correlates well with the observation that rGluH displayed weak binding affinity (< 40%) to the insoluble polymer. The biocatalytic hydrolysis of D-laminarioligosaccharides with a degree of polymerization between 3 and 6 and laminarin generally resulted in the formation of D-laminaribiose as the predominant product and D-glucose as the secondary product, with a ratio of approximately 4:1. These findings suggest that highly active rGluH is an acidic, cold-adapted D-laminaribiose- and D-glucose-releasing GH16 endo-β-1,3-glucanase, which can be exploited as a valuable biocatalyst for facilitating low temperature preservation of foods. [ABSTRACT FROM AUTHOR]

This review examines microbial polysaccharides' properties relevant to their use in packaging and pharmaceutical applications. Microbial polysaccharides are produced by enzymes found in the cell walls of microbes. Xanthan gum, curdlan gum, pullulan, and bacterial cellulose are high-molecular-weight substances consisting of sugar residues linked by glycoside bonds. These polysaccharides have linear or highly branched molecular structures. Packaging based on microbial polysaccharides is readily biodegradable and can be considered as a renewable energy source with the potential to reduce environmental impact. In addition, microbial polysaccharides have antioxidant and prebiotic properties. The physico-chemical properties of microbial polysaccharide-based films, including tensile strength and elongation at break, are also evaluated. These materials' potential as multifunctional packaging solutions in the food industry is demonstrated. In addition, their possible use in medicine as a drug delivery system is also considered. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION This study investigated the contribution of 11 polysaccharides (2%, w/w), including pectin (PC), κ‐carrageenan (KC), ι‐carrageenan (IC), gellan gum (GG), guar gum (GM), sodium alginate (SA), konjac gum (KG), gum arabic (GA), fucoidan (FC), locust bean gum (LBG), and curdlan (CD), to the gel and microstructural properties of Meretrix meretrix clam gel (MMG).The hardness, springiness and chewiness of MMG with KC, IC, GG, SA and FC addition increased by ~10%–250%, while PC, GM, KG and LBG groups decreased by ~0.6% to 69%. KC, IC, SA, GG and FC decreased the cooking loss rate (CLR) by 69.4% to 88.7% and correspondingly enhanced the water holding capacity (WHC) by 10.2% to 21.4%, which was accompanied by an increased bound water and immobilized water area and high hydrogen proton density. The addition of KC transformed the MMG microstructure from a loose network with large pores to a compact, dense network, reducing lacunarity by 57.9%. The primary intermolecular forces in MMG with the incorporation of KC, IC, GG, SA and FC were hydrophobic interactions and disulfide bonds, which increased by 32.8%‐105.3% and 45.6%‐114.5% than MMG alone, respectively.Collectively, KC, IC, GG, SA and FC could improve the gel properties of MMG and the strongest synergistic combination was found in the MMG/KC system. This study suggests that the incorporation of polysaccharides is a strategy with potential for modifying the gel properties of shellfish surimi products. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Purpose: Acquired resistance to immune checkpoint blockers (ICBs) is a major barrier in cancer treatment, emphasizing the need for innovative strategies. Dectin-1 (gene Clec7a) is a C-type lectin receptor best known for its ability to recognize β-glucan-rich structures in fungal cell walls. While Dectin-1 is expressed in myeloid cells and tumor cells, its significance in cancer remains the subject of controversy. Methods: Using Celc7a-/- mice and curdlan administration to stimulate Dectin-1 signaling, we explored its impact. VISTA KO mice were employed to assess VISTA's role, and bulk RNAseq analyzed curdlan effects on neutrophils. Results: Our findings reveal myeloid cells as primary Dectin-1 expressing cells in the tumor microenvironment (TME), displaying an activated phenotype. Strong Dectin-1 co-expression/co-localization with VISTA and PD-L1 in TME myeloid cells was observed. While Dectin-1 deletion lacked protective effects, curdlan stimulation significantly curtailed B16-F10 tumor progression. RNAseq and pathway analyses supported curdlan's role in triggering a cascade of events leading to increased production of pro-inflammatory mediators, potentially resulting in the recruitment and activation of immune cells. Moreover, we identified a heterogeneous subset of Dectin-1+ effector T cells in the TME. Similar to mice, human myeloid cells are the prominent cells expressing Dectin-1 in cancer patients. Conclusion: Our study proposes Dectin-1 as a potential adjunctive target with ICBs, orchestrating a comprehensive engagement of innate and adaptive immune responses in melanoma. This innovative approach holds promise for overcoming acquired resistance to ICBs in cancer treatment, offering avenues for further exploration and development. [ABSTRACT FROM AUTHOR]

Summary: In this study, temperature‐dependent changes in the molecular conformation of curdlan were investigated using differential scanning calorimetry (DSC), microscopic observation, particle size analysis and molecular dynamics (MD) simulation. The DSC results showed that the gel formation temperature of curdlan is related to the glass transition temperature (Tg). The results of microscopic observation and particle size analysis showed that the curdlan particles swelled with increasing temperature, and the original rough and irregular surface morphology gradually became relatively smooth. The MD results show that the weak gel is the result of hydrogen bonds and hydrophobic interaction, whereas the strong gel is less affected by hydrogen bonds, and hydrophobic interaction is the main driving force. [ABSTRACT FROM AUTHOR]

This study aimed to obtain a lentinan-specific fluorescent probe for the in situ visualization of lentinan. A carbohydrate-binding module with potential lentinan-binding capacity was discovered in a β-1,3-D-glucanase by using the bioinformatics techniques, and further recombinantly expressed. The binding specificity of the expressed protein, which was named as LBM was determined by the microtiter plate assays. The results indicated that LBM displayed a desired specificity for lentinan. The protein exhibited positive binding signals to lentinan, while could not bind to several examined polysaccharides including barley β-glucan, curdlan, or konjac glucomannan. Furthermore, the first lentinan-specific fluorescent probe was successfully constructed by fusing LBM with a green fluorescent protein EmGFP, based on which the in situ visualization of lentinan in Lentinula edodes was realized. It was shown that lentinan was not only presented in the mycelial cell wall, but also amorphously distributed in the interstitial space and inside the cell. The construction of the EmGFP-LBM provided a promising tool for the in situ visualization of lentinan. [ABSTRACT FROM AUTHOR]

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Copyright of Science & Technology of Food Industry is the property of Science & Technology of Food Industry 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.)

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department 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.)

The effective treatment of chronic wounds represents a critical global medical challenge demanding urgent attention. Persistent inflammation, driven by an excess of reactive oxygen radicals, sets in motion a detrimental cycle leading to chronic wounds and impeding the natural healing process. This study develops a sprayable wound dressing by covalently grafting amino fullerene to carboxymethylated curdlan (CMC‐C). This novel dressing exhibits excellent biocompatibility, antioxidant, and reactive oxygen species scavenging properties. Furthermore, it demonstrates a targeted affinity for HEK‐a cells, efficiently reducing the inflammatory response while promoting cell proliferation and migration in vitro. Moreover, the animal experiment investigations reveal that CMC‐C significantly accelerates chronic wounds healing by regulating the inflammatory process, promoting collagen deposition, and improving vascularization. These results demonstrate the potential of the sprayable dressing (CMC‐C) in curing the healing of chronic wounds through the modulation of the inflammatory microenvironment. Overall, the sprayable hydrogel dressing based on water‐soluble derivative of fullerene and curdlan emerges as a potential approach for clinical applications in the treatment of chronic wounds. [ABSTRACT FROM AUTHOR]

The EFSA Panel on Food Additives and Flavourings (FAF) provides a scientific opinion on the safety of curdlan as a new food additive used as firming and gelling agent, stabiliser, thickener. Curdlan is a high molecular weight polysaccharide consisting of β‐1,3‐linked glucose units, produced by fermentation from Rhizobium radiobacter biovar 1 strain NTK‐u. The toxicological dataset consisted of sub‐chronic, chronic and carcinogenicity, reproductive and developmental toxicity studies as well as genotoxicity. In vivo data showed that curdlan is not absorbed as such but is extensively metabolised by the gut microbiota into CO2 and other innocuous compounds. Curdlan was not genotoxic and was well‐tolerated with no overt organ‐specific toxicity. Effects observed at very high doses of curdlan, such as decreased growth and increased cecum weight, are common for indigestible bulking compounds and therefore considered physiological responses. In a combined three‐generation reproductive and developmental toxicity study, decreased pup weight was observed during lactation at 7500 mg curdlan/kg body weight (bw) per day, the highest dose tested. The Panel considered the observed effects as treatment‐related and adverse, although likely secondary to nutritional imbalance and identified a conservative no observed adverse effect level (NOAEL) of 2500 mg/kg bw per day. Despite the limitations noted in the dataset, the Panel was able to conclude applying the margin of exposure (MOE) approach. Given that curdlan and its break‐down products are not absorbed and that the identified adverse effect is neither systemic nor local, no adjustment factor was deemed necessary. Thus, an MOE of at least 1 was considered sufficient. The highest exposure estimate was 1441 mg/kg bw per day in toddlers at the 95th percentile of the proposed maximum use level exposure assessment scenario. The Panel concluded that there is no safety concern for the use of curdlan as a food additive at the proposed uses and use levels. [ABSTRACT FROM AUTHOR]

Exopolysaccharides (EPSs) are a diverse class of biopolymers synthesized by microorganisms under environmental stress conditions, such as pH, temperature, light intensity, and salinity. They offer biodegradable and environmentally friendly alternatives to synthetic polymers. Their structural versatility and functional properties make them unique in various industries, including food, pharmaceuticals, biomedicine, cosmetics, textiles, petroleum, and environmental remediation. In this way, among the well-known EPSs, homopolysaccharides like dextran, bacterial cellulose, curdlan, and levan, as well as heteropolysaccharides like xanthan gum, alginate, gellan, and kefiran, have found widespread applications in numerous fields. However, recent attention has focused on the potential role of extremophile bacteria in producing EPSs with novel and unusual protective and biological features under extreme conditions. Therefore, this review provides an overview of the functional properties and applications of the commonly employed EPSs. It emphasizes their importance in various industries and scientific endeavors while highlighting the raised interest in exploring EPSs with novel compositions, structures, and properties, including underexplored protective functionalities. Nevertheless, despite the potential benefits of EPSs, challenges persist. Hence, this review discusses these challenges, explores opportunities, and outlines future directions, focusing on their impact on developing innovative, sustainable, and functional materials. [ABSTRACT FROM AUTHOR]

Summary: The purpose of the study was to explore the effects of curdlan on the textural and sensory qualities of frozen steamed bread (FSB), as well as water state and starch properties during freezing. The results showed that incorporation of curdlan improved the springiness and resilience, while it reduced the hardness and chewiness of FSB. The quality deterioration of FSB was largely caused by the growth and recrystalisation of ice crystals. However, incorporation of curdlan mitigated this adverse impact by regulating water state. Specifically, it increased water content, inhibited water migration, and significantly decreased freezable water content. Additionally, curdlan also decreased starch relative crystallinity, which hindered its retrogradation and thus maintained the overall quality of FSB. Notably, inclusion of 0.5% curdlan exhibited optimal effectiveness in improving quality as evidenced by the highest sensory score obtained. [ABSTRACT FROM AUTHOR]

In this study, a curdlan-producing bacterium was isolated from Cow pea soil and identified as Priestia megaterium based on 16 S rRNA sequencing. To identify the most suitable carbon and nitrogen sources for curdlan production, submerged fermentation studies with different sources was carried out. To enhance the curdlan yield, optimization by one-factor-at-a-time approach was conducted. The optimal fermentation media consisted of 15% (w/v) sucrose, 0.1% (w/v) urea, 0.1% (w/v) KH2PO4, 0.04% (w/v) MgSO4·7H2O, trace elements, initial pH of 7.0 with 10% (v/v) inoculum size and agitation speed of 180 rpm. Kinetics of growth, curdlan yield, sucrose and ammonia depletion were studied for a period of 168 h. Maximum curdlan yield (0.31 g/L) was achieved at 96 h of fermentation. At this point, the fermentation media had an optical density of 9.68, biomass concentration of 4.26 mg/mL, and viable count of 2.4 × 104 CFU/mL. Additionally, the maximum percentage consumption of sucrose and ammonia over 168 h of fermentation were 75 and 62.5%, respectively. Finally, the identity of biopolymer curdlan was validated through characterization techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Thermogravimetric analysis (TGA). Some characteristic features of curdlan such as the β-1,3-linkage was depicted by the absorption band at 890 cm−1 in FTIR, flaky granules with irregularities as seen in SEM, and thermal degradation between 235 and 350 °C by TGA. To the best of our knowledge, this is the first report on curdlan production from Priestia megaterium. [ABSTRACT FROM AUTHOR]

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The effects of the addition of curdlan gel with two different forms, thermal reversible curdlan gum (TRC) and thermal irreversible curdlan gum (TIRC) on the gelling properties and in vitro digestibility of myofibrillar proteins (MP) gel were investigated. The results showed that the gel strength and water holding capacity of MP gel significantly increased with increasing TRC or TIRC concentration (P<0.05), and reached the maximum value at 0.4%, which was confirmed by dynamic rheological behavior. Meanwhile, the addition of TRC or TIRC promoted the transformation of α-helix into β-sheet, and the hydrophobic interaction and disulfide bond were the primary forces of mixed gels. The microstructures revealed that the addition of TRC or TIRC promoted the formation of the dense and uniform protein network structure. However, the modes of interactions between TRC or TIRC and MP induced the different patterns for the gel formation, resulting in the differences in the microstructure of MP gels. In addition, the addition of TRC or TIRC inhibited protein hydrolysis into small peptides and amino acids, which significantly decreased in vitro protein digestibility (P<0.05). Especially when the supplemental level was 0.3% (w/w), the digestibility was reduced from 77.53% to 71.66%. However, no significant effect on the in vitro digestibility of MP gels was observed for each addition form of curdlan (P>0.05). Therefore, this study provides a theoretical basis for the effect of TRC or TIRC on the formation and in vitro digestion of MP gel, and lays a technical support for the application of curdlan gum in meat industry. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department 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.)

Summary: The inherent poor cooking quality and poor texture of mixed‐grain pasta limit consumer acceptance. This study systematically investigated the effect of curdlan in the processing of sweet potato puree oat mixed‐grain noodles, and comprehensively analysed a number of key indicators such as cooking characteristics, moisture state, texture properties, microstructure, starch crystallinity characteristics, short‐range ordered structure and thermal properties. At the production practice level, the study clearly indicated that the 0.6% curdlan addition ratio was the best solution in sweet potato puree oat mixed‐grain noodles processing. This finding not only significantly reduces the fracture rate, water absorption rate and cooking loss rate during the cooking process, but also significantly improves the quality and yield of the product, and brings significant improvement in the taste and texture of the noodles, which is of great significance for industrial production. In the microstructural and molecular studies, we revealed how curdlan could enhance the structural stability and mechanical strength of noodles by promoting the uniform distribution of starch granules in the gluten protein network. Further, through X‐ray diffraction, ordered structure and thermal property analyses, we have found that colchicine can effectively regulate the interactions of hydrogen bonding between starch and the content of straight‐chain and branched‐chain starch, which significantly reduces the crystallinity, ordered short‐chain structure and enthalpy of pasting of starch in the pasta. These in‐depth research results not only help us to understand more comprehensively the formation mechanism of the modification of pasta quality by curdlan, but also provide a solid theoretical foundation and practical guidance for the improvement of pasta quality in mixed grains. [ABSTRACT FROM AUTHOR]

Ectopic teeth are an eruption disorder in which teeth are located in anatomical structures where, physiologically, they should not occur. An ectopic tooth is a very rare phenomenon, affecting approximately 0.5% of the canine population, and few descriptions of the treatment of such teeth in dogs can be found in the available literature. This article describes the diagnostic and therapeutic handling of cavities following extraction of ectopic teeth in nine dogs. The cases are subdivided into uncomplicated (when the ectopic tooth was encapsulated in the surrounding connective tissue, without lysis of the bone around the tooth) and complicated (in which, in addition to the presence of the ectopic tooth, a dentigerous cyst had formed). Four cases of complicated ectopic teeth are described in more detail. In this study, special attention was paid not only to the technique of tooth extraction itself but also to the method of securing and healing large bone defects after the extraction using hydroxyapatite curdlan polymer. Owing to the plastic properties of the bone substitute preparation, it was possible to implant the material without enlarging the bone defect created during the tooth extraction. Control radiographs showed features of bone regeneration, and clinical examination at both the early and late stages revealed no postoperative complications. [ABSTRACT FROM AUTHOR]

The dehydrated chemical sludge has a strong water-holding capacity and is difficult to treat further and utilize. To explore the internal mechanism of sludge beam water, the molecular dynamics simulation method was used to study the interaction between Curdlan polysaccharide and water. The effects of water content, temperature, and chain number of polysaccharides on the binding capacity of polysaccharides were analyzed. The radial distribution function, number of hydrogen bonds, binding energy, etc., characterized the interaction properties. It was found that polysaccharides mainly use hydrogen bonding to bind water molecules, and the hydroxyl group connected to the main chain has the most vital binding capacity; the saturated water content of a single chain was 44.14%. The binding energy at different temperatures was also calculated. The results showed that 358 K was the critical point. When the temperature exceeds 358 K, the polysaccharide and water molecules turn from attraction to repulsion. At this time, polysaccharide molecules can no longer bind most of the water molecules in the system; the water molecules move more freely. Additionally, the increased number of polysaccharide chains will increase the interconnectedness to each other and wrap water molecules inside the polysaccharide molecules, then solidified water on the polysaccharide's surface, enhancing the polysaccharide's water bunching capacity. [ABSTRACT FROM AUTHOR]

Hydrogels based on biocompatible polysaccharides with biological activity that can slowly release an active principle at the wound site represent promising alternatives to traditional wound dressing materials. In this respect, new hydrogels based on curdlan derivative with 2-hydroxypropyl dimethyl octyl ammonium groups (QCurd) and native curdlan (Curd) were obtained at room temperature by covalent cross-linking using a diepoxy cross-linking agent. The chemical structure of the QCurd/Curd hydrogels was investigated by Fourier transform infrared spectroscopy (FTIR) spectroscopy. Scanning electron microscopy (SEM) revealed well-defined regulated pores with an average diameter between 50 and 75 μm, and hydrophobic micro-domains of about 5 μm on the pore walls. The high swelling rate (21–24 gwater/ghydrogel) and low elastic modulus values (7–14 kPa) make them ideal for medical applications as wound dressings. To evaluate the possible use of the curdlan-based hydrogels as active dressings, the loading capacity and release kinetics of diclofenac, taken as a model drug, were studied under simulated physiological skin conditions. Several mathematical models have been applied to evaluate drug transport processes and to calculate the diffusion coefficients. The prepared QCurd/Curd hydrogels were found to have good antibacterial properties, showing a bacteriostatic effect after 48 h against S. aureus, MRSA, E. coli, and P. aeruginosa. The retarded drug delivery and antimicrobial properties of the new hydrogels support our hypothesis that they are candidates for the manufacture of wound dressings. [ABSTRACT FROM AUTHOR]

Curdlan gum (CG) is a β-(1→3)-linked glucan insoluble exopolysaccharide produced by marine bacteria Enterobacter cloacae subsp. dissolvens RSW2n. In this study, CG was used to fabricate gallic acid-encapsulated curdlan gum nanoparticles (GA-CG NPs) for effectively delivering the drug into breast cancer cells (MCF-7) using glutaraldehyde as the crosslinking agent and a modified desolvation method was adopted. The fabricated GA-CG NPs were characterized by UV–Visible spectra, FT-IR, XRD, particle size analyzer and HR-TEM. The stability of GA-CG NPs was evaluated at various pH and simulated body fluids. In vitro drug release and its kinetics were examined through the dissolution mechanism using mathematical prediction models. The encapsulation efficiency and loading capacity of gallic acid was 88.215 ± 3.242% and 8.26 ± 0.021%, respectively. The antioxidant and cytotoxic potential of GA-CG NPs were evaluated through in vitro assays. The IC50 of GA-CG NPs against MCF-7 cells was found to be 16.75 µg × mL−1. The induction of apoptosis in MCF-7 cells was confirmed through flow cytometry. Nuclei condensation, loss of mitochondrial membrane potential, and deformed cell membranes were visualized by staining. Curdlan gum effectively controls the release of gallic acid as the gel matrix slowly degrades and releases the encapsulated gallic acid. Hence, the curdlan gum produced by E. cloacae could be considered as promising candidate for drug delivery application for degenerative disorder. [ABSTRACT FROM AUTHOR]

Polymers can enhance oil recovery depending on viscoelasticity. In a field, during polymer flow through porous strata, continuous shear forces result in severe viscosity loss. However, polymers with great shear resistance result in limited migration distance. One solution to the above dilemma is to regulate viscosity, which enables a polymer to migrate long distances through pores with low viscosity and subsequently maintain high viscosity in deep reservoirs. The viscosity of curdlan can be regulated by changing temperature. By curdlan, we mean a biopolymer that shows applications in food industry. However, regarding oil reservoirs, it is unclear whether curdlan viscosity can be effectively regulated in pores. To reveal the feasibility of curdlan viscosity regulation to enhance oil recovery, flooding experiments combined with micro-particle image velocimetry were conducted in a two-dimensional pore network to investigate flow fields of curdlan solutions (0.25%, 0.5%, 1%, and 2%, w/v) at different temperatures (40, 65, and 85 °C). As a result, at 40 °C, curdlan solution (0.25%) easily migrated with low viscosity loss and low adsorption [88.3% original throat diameter (OTD)], and the mobility of curdlan was higher than hydrolyzed polyacrylamide. After heating (65 °C), the viscoelasticity, adsorption (55.1% OTD), and flow resistance (injection pressure, 2.2–8.8 kPa) of curdlan increased, and the greater adsorption capacity of curdlan than xanthan gum led to a more homogeneous flow field [average velocity ratio (Rm), from 2.6 to 1.1]. Since a homogeneous flow field indicated better sweep efficiency, curdlan regulated by temperature could achieve both long-distance migration and improved sweep efficiency in deep strata. These results suggested that viscosity regulation by curdlan could potentially improve oil recovery in water-flooded reservoirs. [ABSTRACT FROM AUTHOR]

The effects of curdlan concentrations (0, 3, 5, and 7%) on the physical, textural, and sensorial properties of canned dodol (Candol) were investigated. The incorporation of curdlan in canned dodol significantly influenced several attributes of the product, including pH, total soluble solids (TSS), water activity (aw), moisture content, colour, texture, and microstructure. Curdlan decreased the pH level and increased the TSS level, while decreasing the moisture content and aw in certain samples. It also impacted the texture of dodol, with one sample (Candol-5) showing a texture similar to commercially available dodol. Additionally, microstructural differences were observed, with Candol-5 exhibiting the smallest pores and a more compact gel structure. Sensory panellists preferred the texture of Candol-5 over Candol-0, and its sensory rating was more similar to that of the commercial dodol, with no significant differences observed. In summary, curdlan could be a beneficial ingredient for improving the quality and acceptability of canned dodol, offering valuable insights for the development of innovative dodol products in the future. [ABSTRACT FROM AUTHOR]

β-1,3-glucans are a kind of natural polysaccharide with immunomodulatory, antitumor, and anti-inflammatory properties. Curdlan, as the simplest linear β-1,3-glucan, possesses a variety of biological activities and thermogelation properties. However, due to the complexity and variability of the conformations of curdlan, the exact structure–activity relationship remains unclear. We prepare a chemically crosslinked curdlan hydrogel with the unique single-helical skeleton (named S gel) in 0.4 wt% NaOH at 40 °C, confirmed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). X-ray diffractometry (XRD) data show that S gel maintains the single-helical crystal structure, and the degree of crystallinity of the S gel is ~24%, which is slightly lower than that of the raw powder (~31%). Scanning electron microscopy (SEM) reveals that S gel has a continuous network structure, with large pores measuring 50–200 μm, which is consistent with its high swelling property. Using the 13C high-resolution magic angle spinning nuclear magnetic resonance (HRMAS NMR) method, we determine that most of the single-helical skeleton carbon signals in the swollen S gel are visible, suggesting that the single-helical skeleton of S gel exhibits fascinating mobility at room temperature. Finally, we reveal that the binding of S gel to coagulation Factor G from tachypleus amebocyte lysate increases and saturates at 20 μL tachypleus amebocyte lysate per mg of S gel. Our prepared S gel can avoid the transformation of curdlan conformations and retain the bioactivity of binding to coagulation Factor G, making it a valuable material for use in the food industry and the pharmaceutical field. This work deepens the understanding of the relationship between the single-helical structure and the activity of curdlan, promoting the development and application of β-1,3-glucans. [ABSTRACT FROM AUTHOR]

The aerobic hyperthermophile "Fervidibacter sacchari" catabolizes diverse polysaccharides and is the only cultivated member of the class "Fervidibacteria" within the phylum Armatimonadota. It encodes 117 putative glycoside hydrolases (GHs), including two from GH family 50 (GH50). In this study, we expressed, purified, and functionally characterized one of these GH50 enzymes, Fsa16295Glu. We show that Fsa16295Glu is a ß-1,3-endoglucanase with optimal activity on carboxymethyl curdlan (CM-curdlan) and only weak agarase activity, despite most GH50 enzymes being described as ß-agarases. The purified enzyme has a wide temperature range of 4-95°C (optimal 80°C), making it the first characterized hyperthermophilic representative of GH50. The enzyme is also active at a broad pH range of at least 5.5-11 (optimal 6.5-10). Fsa16295Glu possesses a relatively high kcat/KM of 1.82 × 107 s-1 M-1 with CMcurdlan and degrades CM-curdlan nearly completely to sugar monomers, indicating preferential hydrolysis of glucans containing ß-1,3 linkages. Finally, a phylogenetic analysis of Fsa16295Glu and all other GH50 enzymes revealed that Fsa16295Glu is distant from other characterized enzymes but phylogenetically related to enzymes from thermophilic archaea that were likely acquired horizontally from "Fervidibacteria." Given its functional and phylogenetic novelty, we propose that Fsa16295Glu represents a new enzyme subfamily, GH50_3. [ABSTRACT FROM AUTHOR]

Laminaripentaose (L5)‐producing β‐1,3‐glucanases can preferentially cleave the triple‐helix curdlan into β‐1,3‐glucooligosaccharides, especially L5. In this study, a newly identified member of the glycoside hydrolase family 64, β‐1,3‐glucanase from Streptomyces pratensis (SpGlu64A), was functionally and structurally characterized. SpGlu64A shared highest identity (30%) with a β‐1,3‐glucanase from Streptomyces matensis. The purified SpGlu64A showed maximal activity at pH 7.5 and 50 °C, and exhibited strict substrate specificity toward curdlan (83.1 U·mg−1). It efficiently hydrolyzed curdlan to produce L5 as the end product. The overall structure of SpGlu64A consisted of a barrel domain and a mixed (α/β) domain, which formed an unusually wide groove with a crescent‐like structure. In the two complex structures (SpGlu64A–L3 and SpGlu64A–L4), two oligosaccharide chains were captured and the triple‐helical structure was relatively compatible with the wide groove, which suggested the possibility of binding to the triple‐helical β‐1,3‐glucan. A catalytic framework (β6–β9–β10) and the steric hindrance formed by the side chains of residues Y161, N163, and H393 in the catalytic groove were predicted to complete the exotype‐like cleavage manner. On the basis of the structure, a fusion protein with the CBM56 domain (SpGlu64A–CBM) and a mutant (Y161F; by site‐directed mutation) were obtained, with 1.2‐ and 1.7‐fold increases in specific activity, respectively. Moreover, the combined expression of SpGlu64A–CBM and ‐Y161F improved the enzyme activity by 2.63‐fold. The study will not only be helpful in understanding the reaction mechanism of β‐1,3‐glucanases but will also provide a basis for further enzyme engineering. [ABSTRACT FROM AUTHOR]

A key goal in current research on industrial curdlan production is the expansion of carbon sources for fermentation. In this study, a recombinant bacterial strain, sp-AmyAXCC, capable of fermenting and synthesizing curdlan using dextrin as a carbon source, was produced via heterologous expression of IPTG-inducible α-amylase from Xanthomonas campestris NRRL B-1459 in Agrobacterium tumefaciens ATCC31749. External expression of the enzyme was confirmed by western blotting, and the expression levels of exogenous proteins during the fermentation process were monitored. Additionally, the properties of the curdlan product were characterized using attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray diffraction. The recombinant strain produced curdlan at a titer of 30.40 ± 0.14 g/L, gel strength of 703.5 ± 34.2 g/cm2, and a molecular weight of 3.58 × 106 Da, which is 33% greater than the molecular weight of native curdlan (2.69 × 106 Da). In the batch fermentation of sp-AmyAXCC with 12% dextrin as a carbon source, the titer of curdlan was 66.7 g/L with a yield of 0.56 g/g, and a productivity rate of 0.62 g/L/h at 108 h. The results of this study expand the substrate spectrum for Agrobacterium fermentation in curdlan production and provides guidance for further industrialization of curdlan production. [ABSTRACT FROM AUTHOR]