A Novel Approach to the Use of Xanthan Gum: Evaluation of Probiotic Promoter, Postbiotic Formation and Techno-Functional Effect.

In the present study, the effect of xanthan gum was evaluated on the metabolic activity and survival of two probiotic strains, namely B. lactis and L. casei using in vitro assay and skim milk model system. In vitro assay was carried out identifying by pH, optical cell density (OD), and formation of postbiotics (lactic, acetic, propionic, and butyric acids) in different basal media including glucose, inulin, and xanthan gum as carbon source. The highest pH values were recorded for control (without carbon source) and media with xanthan gum, whereas the media with glucose and xanthan gum had the highest OD values. In comparison to strains, B. lactis had higher pH and lower OD values than L. casei. It was found that xanthan gum supported the formation of postbiotics as a result of bacterial fermentation. In the skim milk model system, xanthan gum did not negatively affect probiotic viability, and the counts of both strains were above the required level for health benefits (8 log cfu g-1) after 28-day storage. The use of xanthan gum in skim milk matrix positively affected techno-functional properties such as syneresis, color, and textural parameters of samples.

Microbial Polysaccharides Extracted from Different Mature Muds of the Euganean Thermal District Show Similar Anti-Inflammatory Activity In Vivo.

The Euganean Thermal District, situated in North-East Italy, is one of Europe's largest and oldest thermal centres. The topical application of its therapeutic thermal muds is recognised by the Italian Health System as a beneficial treatment for patients suffering from arthro-rheumatic diseases. Polysaccharides produced by the mud microbiota have been recently identified as anti-inflammatory bioactive molecules. In this paper we analysed the efficacy of Microbial-Polysaccharides (M-PS) derived from mature muds obtained at different maturation temperatures, both within and outside the codified traditional mud maturation range. M-PSs were extracted from six mature muds produced by five spas of the Euganean Thermal District and investigated for their chemical properties, monosaccharide composition and in vivo anti-inflammatory potential, using the zebrafish model organism. Additionally, mature muds were characterized for their microbiota composition using Next-Generation Sequencing. The results showed that all M-PSs exhibit similar anti-inflammatory potential, referable to their comparable chemical composition. This consistency was observed despite changes in cyanobacteria populations, suggesting a possible role of the entire microbial community in shaping the properties of these biomolecules. These findings highlight the importance of scientific research in untangling the origins of the therapeutic efficacy of Euganean Thermal muds in the treatment of chronic inflammatory conditions.

In Vivo and In Vitro Interactions between Exopolysaccharides from Bacillus thuringensis HD270 and Vip3Aa11 Protein.

Bacillus thuringiensis (Bt) secretes the nutritional insecticidal protein Vip3Aa11, which exhibits high toxicity against the fall armyworm (Spodoptera frugiperda). The Bt HD270 extracellular polysaccharide (EPS) enhances the toxicity of Vip3Aa11 protoxin against S. frugiperda by enhancing the attachment of brush border membrane vesicles (BBMVs). However, how EPS-HD270 interacts with Vip3Aa11 protoxin in vivo and the effect of EPS-HD270 on the toxicity of activated Vip3Aa11 toxin are not yet clear. Our results indicated that there is an interaction between mannose, a monosaccharide that composes EPS-HD270, and Vip3Aa11 protoxin, with a dissociation constant of Kd = 16.75 ± 0.95 mmol/L. When EPS-HD270 and Vip3Aa11 protoxin were simultaneously fed to third-instar larvae, laser confocal microscopy observations revealed the co-localization of the two compounds near the midgut wall, which aggravated the damage to BBMVs. EPS-HD270 did not have a synergistic insecticidal effect on the activated Vip3Aa11 protein against S. frugiperda. The activated Vip3Aa11 toxin demonstrated a significantly reduced binding capacity (548.73 ± 82.87 nmol/L) towards EPS-HD270 in comparison to the protoxin (34.96 ± 9.00 nmol/L). Furthermore, this activation diminished the affinity of EPS-HD270 for BBMVs. This study provides important evidence for further elucidating the synergistic insecticidal mechanism between extracellular polysaccharides and Vip3Aa11 protein both in vivo and in vitro.

Xanthan gum-based edible coating effectively preserve postharvest quality of 'Gola' guava fruits by regulating physiological and biochemical processes.

BACKGROUND: Guava is a fruit prone to rapid spoilage following harvest, attributed to continuous and swift physicochemical transformations, leading to substantial postharvest losses. This study explored the efficacy of xanthan gum (XG) coatings applied at various concentrations (0.25, 0.5, and 0.75%) on guava fruits (Gola cultivar) over a 15-day storage period. RESULTS: The results indicated that XG coatings, particularly at 0.75%, substantially mitigated moisture loss and decay, presenting an optimal concentration. The coated fruits exhibited a modified total soluble soluble solids, an increased total titratable acidity, and an enhanced sugar-acid ratio, collectively enhancing overall quality. Furthermore, the XG coatings demonstrated the remarkable ability to preserve bioactive compounds, such as total phenolics, flavonoids, and antioxidants, while minimizing the levels of oxidative stress markers, such as electrolyte leakage, malondialdehyde, and H2O2. The coatings also influenced cell wall components, maintaining levels of hemicellulose, cellulose, and protopectin while reducing water-soluble pectin. Quantitative analysis of ROS-scavenging enzymes, including superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase, revealed significant increases in their activities in the XG-coated fruits compared to those in the control fruits. Specifically, on day 15, the 0.75% XG coating demonstrated the highest SOD and CAT activities while minimizing the reduction in APX activity. Moreover, XG coatings mitigated the activities of fruit-softening enzymes, including pectin methylesterase, polygalacturonase, and cellulase. CONCLUSIONS: This study concludes that XG coatings play a crucial role in preserving postharvest quality of guava fruits by regulating various physiological and biochemical processes. These findings offer valuable insights into the potential application of XG as a natural coating to extend the shelf life and maintain the quality of guava fruits during storage.

A xanthan gum and carbomer-codispersed divalent manganese ion-loaded tannic acid nanoparticle adjuvanted inactivated pseudorabies virus vaccine induces balanced humoral and cellular immune responses.

Adjuvants including aluminum adjuvant (Alum) and oil-water emulsion have been widely used in inactivated pseudorabies virus (PRV) vaccines to improve their performance, however, they are not sufficient to protect from PRV infection because of the weak immune response and poor Th1-type immune response. Divalent manganese ion (Mn2+) has been reported to increase the cellular immune response significantly. In this work, a xanthan gum and carbomer-dispersed Mn2+-loaded tannic acid-polyethylene glycol (TPMnXC) nanoparticle colloid is developed and used as an adjuvant to improve the performance of the inactivated PRV vaccine. The good in vitro and in vivo biocompatibility of the developed TPMnXC colloid has been confirmed by the cell viability assay, erythrocyte hemolysis, blood routine analysis, and histological analysis of mouse organs and injection site. The TPMnXC-adjuvanted inactivated PRV vaccine (TPMnXC@PRV) significantly promotes higher and more balanced immune responses indicating with an increased specific total IgG antibody and IgG2a/IgG1 ratio, efficient splenocytes proliferation, and elevated Th1- and Th2-type cytokine secretion than those of control groups. Wild PRV challenge experiment is performed using mice as a model animal, achieving a protection rate of up to 86.67 %, which is much higher than those observed from the commercial Alum. This work not only demonstrates the high potentiality of TPMnXC in practical applications but also provides a new way to develop the Mn2+-loaded nanoadjuvant for veterinary vaccines.

4-hydroxy-3-methoxybenzaldehyde causes attrition of biofilm formation and quorum sensing-associated virulence factors of Streptococcus mutans.

OBJECTIVE: The present study investigated the effects of 4-hydroxy-3-methoxybenzaldehyde (4-H-3-MB) against Streptococcus mutans (S. mutans) using an in vitro cariogenic biofilm model. DESIGN: The antimicrobial susceptibility of biofilm-forming S. mutans was evaluated by disc diffusion method. In vitro investigations were performed using crystal violet staining assay (biofilm assay), exopolysaccharide (EPS) assay, acid production, growth curve analysis, optical microscopic, and FE-SEM analyses to determine the antibiofilm activity of 4-H-3-MB. RESULTS: S. mutans (SDC-05) was resistant to ampicillin, piperacillin/tazobactam and ceftriaxone, whereas the other strains of S. mutans (SDC-01, 02, 03 and SDC-04) were sensitive to all the antibiotics tested. 4-H-3-MB showed promising antibiofilm activity on S. mutans UA159 (79.81 %, 67.76 % and 56.31 %) and S. mutans SDC-05 (77.00 %, 59.48 % and 48.22 %) at the lowest concentration of 0.2, 0.1, 0.05 mg/ml. 4-H-3-MB did not inhibit bacterial growth even at concentrations 0.2 mg/ml. Similarly, 4-H-3-MB led to significant attrition in exopolysaccharide (EPS) and acid production by S. mutans UA159 and S. mutans (SDC-05) at the concentration of 0.2, 0.1 mg/ml, respectively. Optical microscopy and FE-SEM analysis 4-H-3-MB reduced the biofilm thickness of S. mutans UA159 and S. mutans SDC-05 relative to the untreated specimens. CONCLUSION: 4-H-3-MB significantly inhibited biofilm formation by S. mutans in a dose-dependent manner. Hence, our findings indicate that the active principle of 4-H-3-MB could be used as a biofilm inhibiting agent against S. mutans.

Effect of a phthalate derivative purified from Bacillus zhangzhouensis SK4 on quorum sensing regulated virulence factors of Pseudomonas aeruginosa.

Pseudomonas aeruginosa causes life-threatening diseases and is resistant to almost all conventional antibiotics. The quorum sensing (QS) system of P. aeruginosa contributes to many pathogenic factors some of which are pigment production, motility, and biofilm. The disruption of quorum sensing system may be an impactful strategy to deal with infections. The present study investigates the anti-quorum sensing property of a bioactive molecule extracted from marine epibiotic bacteria present on the surface of seaweeds. Among all the isolates tested against monitor strain Chromobacterium violaceum (MTCC 2656), the one with the highest activity was identified as Bacillus zhangzhouensis SK4. The culture supernatant was extracted with chloroform which was then partially purified by TLC and column chromatography. The probable anti-QS compound was identified as 1,2-benzenedicarboxylic acid, bis (2-methylpropyl ester) by GC-MS and NMR analysis. The treatment of P. aeruginosa MCC 3457 with the lead compound resulted in the reduced production of pyocyanin, rhamnolipids, exopolysaccharide, biofilm, and motility. The observations of light and scanning electron microscopy also supported the biofilm inhibition. The lead compound showed synergism with the meropenem antibiotic and significantly reduced MIC. The molecular docking and pharmacokinetics study predicted 1, 2-benzenedicarboxylic acid, bis (2-methylpropyl ester), a phthalate derivative as a good drug candidate. The molecular dynamics study was also performed to check the stability of the lead compound and LasR complex. Further, lead compounds did not exhibit any cytotoxicity when tested on human embryonic kidney cells. As per our knowledge, this is the first report on the anti-QS activity of B. zhangzhouensis SK4, indicating that epibiotic bacteria can be a possible source of novel compounds to deal with the multidrug resistance phenomenon.

Microbial exopolysaccharides: Unveiling the pharmacological aspects for therapeutic advancements.

Microbial exopolysaccharides (EPSs) have emerged as a fascinating area of research in the field of pharmacology due to their diverse and potent biological activities. This review paper aims to provide a comprehensive overview of the pharmacological properties exhibited by EPSs, shedding light on their potential applications in various therapeutic areas. The review begins by introducing EPSs, exploring their various sources, significance in microbial growth and survival, and their applications across different industries. Subsequently, a thorough examination of the pharmaceutical properties of microbial EPSs unveils their antioxidant, immunomodulatory, antimicrobial, antidepressant, antidiabetic, antiviral, antihyperlipidemic, hepatoprotective, anti-inflammatory, and anticancer activities. Mechanistic insights into how different EPSs exert these therapeutic effects have also been discussed in this review. The review also provides comprehensive information about the monosaccharide composition, backbone, branches, glycosidic bonds, and molecular weight of pharmacologically active EPSs from various microbial sources. Furthermore, the factors that can affect the pharmacological activities of EPSs and approaches to improve the EPSs' pharmacological activity have also been discussed. In conclusion, this review illuminates the immense pharmaceutical promise of microbial EPS as versatile bioactive compounds with wide-ranging therapeutic applications. By elucidating their structural features, biological activities, and potential applications, this review aims to catalyze further research and development efforts in leveraging the pharmaceutical potential of microbial EPS for the advancement of human health and well-being, while also contributing to sustainable and environmentally friendly practices in the pharmaceutical industry.

Purification of exopolysaccharide produced from Lactobacillus spp. using ionic-liquid as adjuvant in alcohol/salt-based aqueous two-phase system for its antidiabetic properties.

Diabetes is a chronic, metabolic disease characterized by hyperglycemia resulting from either insufficient insulin production or impaired cellular response to insulin. Exopolysaccharides (EPS) produced by Lactobacillus spp. demonstrated promising therapeutic potential in terms of their anti-diabetic properties. Extraction and purification of EPS produced by Lactobacillus acidophilus and Limosilactobacillus reuteri were performed using ethanol precipitation, followed by alcohol/salt based aqueous two-phase system (ATPS). The purification process involved ethanol precipitation followed by an alcohol/salt-based ATPS. The study systematically investigated various purification parameters in ATPS, including ethanol concentration, type and concentration of ionic liquid, type and concentration of salt and pH of salt. Purified EPS contents from L. acidophilus (63.30 µg/mL) and L. reuteri (146.48 µg/mL) were obtained under optimum conditions of ATPS which consisted of 30 % (w/w) ethanol, 25 % (w/w) dipotassium hydrogen phosphate at pH 10 and 2 % (w/w) 1-butyl-3-methylimidazolium octyl sulfate. The extracted EPS content was determined using phenol sulphuric acid method. In α-amylase inhibition tests, the inhibitory rate was found to be 92.52 % (L. reuteri) and 90.64 % (L. acidophilus), while in α-glucosidase inhibition tests, the inhibitory rate was 73.58 % (L. reuteri) and 68.77 % (L. acidophilus), based on the optimized parameters selected in ATPS. These results suggest that the purified EPS derived from the postbiotics of Lactobacillus spp. hold promise as potential antidiabetic agents.

Photo-triggered caffeic acid delivery via psyllium polysaccharide- gellan gum-based injectable bionanogel for epidermoid carcinoma treatment.

Here, the simultaneous effect of chemo- and photothermal therapy against epidermoid carcinoma (EC) was investigated. A novel hydrogel, termed bionanogel (BNG), was designed using psyllium mucilage polysaccharide and bacterial gellan gum, incorporated with nanocomplex carrying caffeic acid (CA) and IR-820, and further characterized. The dual effect of BNG and 808 nm laser (BNG + L) on EC was investigated. Staining and scratch assays were performed to analyze their therapeutic effect on EC. In vivo evaluations of BNG + L in xenograft models were performed. Rapid transition, limited swelling, degradability and high tensile strength indicated BNG stability and sustained drug release. Irradiation with 808 nm laser light at 1.25 W /cm2 for 4 min resulted in a temperature increase of 53 °C and facilitated cell ablation. The in vitro studies showed that BNG + L suppressed cancer progression via a late apoptotic effect. The in vivo study showed that the slow release of CA from BNG + L significantly attenuated EC with low mitotic index and downregulation of proteins involved in cancer proliferation such as EGFR, AKT, PI3K, ERK, mTOR and HIF-1α. Thus, BNG could be a novel medium for targeted and controlled drug delivery for the treatment of epidermoid cancer when triggered by NIR light.

Prebiotic levan type fructan from Bacillus subtilis PR-C18 as a potent antibiofilm agent: Structural elucidation and in silico analysis.

The global demand for therapeutic prebiotics persuades the quest for novel exopolysaccharides that can retard the growth of pathobionts and healthcare-associated pathogens. In this regard, an exopolysaccharide (3.69 mg/mL) producing strain showing prebiotic and antibiofilm activity was isolated from indigenous pineapple pomace of Tripura and identified as Bacillus subtilis PR-C18. Zymogram analysis revealed EPS PR-C18 was synthesized by levansucrase (∼57 kDa) with a maximal activity of 4.62 U/mg. Chromatography techniques, FTIR, and NMR spectral data revealed the homopolymeric nature of purified EPS with a molecular weight of 3.40 × 104 Da. SEM and rheological study unveiled its microporous structure and shear-thinning effect. Furthermore, EPS PR-C18 showed remarkable emulsification, flocculation, water retention, water solubilization, and antioxidant activity. DSC-TGA data demonstrated its high thermostability and cytotoxicity analysis verified its nontoxic biocompatible nature. In addition, the antibiofilm activity of EPS PR-C18 was validated using molecular docking, molecular simulation, MM-GBSA and PCA studies, which exhibited its strong binding affinity (-20.79 kcal/moL) with PelD, a virulence factor from Pseudomonas aeruginosa. Together, these findings support the future exploitation of EPS PR-C18 as an additive or adjuvant in food and pharmaceutical sectors.

Characterization and optimization of exopolysaccharide extracted from a newly isolated halotolerant cyanobacterium, Acaryochloris Al-Azhar MNE ON864448.1 with antiviral activity.

Several antiviral agents lost their efficacy due to their severe side effects and virus mutations. This study aimed to identify and optimize the conditions for exopolysaccharide (EPS) production from a newly isolated cyanobacterium, Acaryochloris Al-Azhar MNE ON864448.1, besides exploring its antiviral activity. The cyanobacterial EPS was purified through DEAE-52 cellulose column with a final yield of 83.75%. Different analysis instruments were applied for EPS identification, including Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and gas chromatographic-mass spectrometry (GC-MS). Plackett-Burman's design demonstrated that working volume (X1), EDTA (X2), inoculum size (X3), CaCl2 (X4), and NaCl (X5) are the most important variables influencing EPS production. Central composite design (CCD) exhibited maximum EPS yield (9.27 mg/mL) at a working volume of 300 mL in a 1 L volumetric flask, EDTA 0.002 g/L, inoculum size 7%, CaCl2 0.046 g/L, and NaCl 20 g/L were applied. EPS showed potent antiviral activities at different stages of herpes simplex virus type-1 and 2 (HSV-1, HSV-2), adenovirus (ADV) and coxsackievirus (A16) infections. The highest half-maximal inhibitory concentration (IC50) (6.477 µg/mL) was recorded during HSV-1 internalization mechanism, while the lowest IC50 (0.005669 µg/mL) was recorded during coxsackievirus neutralization mechanism.

3D printing of gellan-dextran methacrylate IPNs in glycerol and their bioadhesion by RGD derivatives.

The ever-growing need for new tissue and organ replacement approaches paved the way for tissue engineering. Successful tissue regeneration requires an appropriate scaffold, which allows cell adhesion and provides mechanical support during tissue repair. In this light, an interpenetrating polymer network (IPN) system based on biocompatible polysaccharides, dextran (Dex) and gellan (Ge), was designed and proposed as a surface that facilitates cell adhesion in tissue engineering applications. The new matrix was developed in glycerol, an unconventional solvent, before the chemical functionalization of the polymer backbone, which provides the system with enhanced properties, such as increased stiffness and bioadhesiveness. Dex was modified introducing methacrylic groups, which are known to be sensitive to UV light. At the same time, Ge was functionalized with RGD moieties, known as promoters for cell adhesion. The printability of the systems was evaluated by exploiting the ability of glycerol to act as a co-initiator in the process, speeding up the kinetics of crosslinking. Following semi-IPNs formation, the solvent was removed by extensive solvent exchange with HEPES and CaCl2, leading to conversion into IPNs due to the ionic gelation of Ge chains. Mechanical properties were investigated and IPNs ability to promote osteoblasts adhesion was evaluated on thin-layer, 3D-printed disk films. Our results show a significant increase in adhesion on hydrogels decorated with RGD moieties, where osteoblasts adopted the spindle-shaped morphology typical of adherent mesenchymal cells. Our findings support the use of RGD-decorated Ge/Dex IPNs as new matrices able to support and facilitate cell adhesion in the perspective of bone tissue regeneration.

Optimization of Culture Medium for the Production of an Exopolysaccharide (p-CY02) with Cryoprotective Activity by Pseudoalteromonas sp. RosPo-2 from the Antarctic Sea.

When cells are exposed to freezing temperatures, high concentrations of cryoprotective agents (CPA) prevent ice crystal formation, thus enhancing cell survival. However, high concentrations of CPAs can also cause cell toxicity. Exopolysaccharides (EPSs) from polar marine environments exhibit lower toxicity and display effects similar to traditional CPA. In this study, we sought to address these issues by i) selecting strains that produce EPS with novel cryoprotective activity, and ii) optimizing culture conditions for EPS production. Sixty-six bacteria producing mucous substances were isolated from the Ross Sea (Antarctic Ocean) using solid marine agar plates. Among them, Pseudoalteromonas sp. RosPo-2 was ultimately selected based on the rheological properties of the produced EPS (p-CY02). Cryoprotective activity experiments demonstrated that p-CY02 exhibited significantly cryoprotective activity at a concentration of 0.8% (w/v) on mammalian cells (HaCaT). This activity was further improved when combined with various concentrations of dimethyl sulfoxide (DMSO) compared to using DMSO alone. Moreover, the survival rate of HaCaT cells treated with 5% (v/v) DMSO and 0.8% (w/v) p-CY02 was measured at 87.9 ± 2.8% after freezing treatment. This suggests that p-CY02 may be developed as a more effective, less toxic, and novel non-permeating CPA. To enhance the production of EPS with cryoprotective activity, Response Surface Methodology (RSM) was implemented, resulting in a 1.64-fold increase in production of EPS with cryoprotective activity.

Interspecific differences and mechanisms of Lactobacillus-derived anti-inflammatory exopolysaccharides.

Accumulating evidence has revealed the anti-inflammatory properties of Lactobacillus-derived exopolysaccharides (EPSs). However, interspecific differences among these Lactobacillus-derived anti-inflammatory EPSs have not been investigated. Cell experiments showed that Limosilactobacillus fermentum, Lacticaseibacillus rhamnosus, and Lactiplantibacillus plantarum-derived EPSs exhibited excellent anti-inflammatory efficacy in vitro. Subsequently, we used Lactobacillus-derived EPSs to treat colitis in mice. There was no significant difference in EPS's repair of the intestinal barrier from the five Lactobacillus species. However, Ligilactobacillus salivarius-derived EPSs and L. plantarum-derived EPSs more potently reduced proinflammatory cytokines (TNF-α, IL-1ß, IL-6, TNF-γ, and IL-17), increasing IL-10 concentrations in the colon. Lactobacillus-derived EPS moieties from five species regulate intestinal bacteria at the strain level. Immunofluorescence staining revealed that owing to the different infiltration and polarization effects of Lactobacillus-derived EPSs on macrophages, the in vitro and in vivo anti-inflammatory effects of Lactobacillus-derived EPSs were inconsistent. The structure-activity relationship showed that Lactobacillus-derived EPSs with high fructose content had excellent anti-inflammatory activity in vivo. The results mentioned above revealed that the anti-inflammatory activity of Lactobacillus-derived EPSs had interspecific variability, and the mechanism of anti-inflammatory action in vitro and in vivo was different.

Polysaccharide-Targeting Lipid Nanoparticles to Kill Gram-Negative Bacteria.

The rapid increase and spread of Gram-negative bacteria resistant to many or all existing treatments threaten a return to the preantibiotic era. The presence of bacterial polysaccharides that impede the penetration of many antimicrobials and protect them from the innate immune system contributes to resistance and pathogenicity. No currently approved antibiotics target the polysaccharide regions of microbes. Here, describe monolaurin-based niosomes, the first lipid nanoparticles that can eliminate bacterial polysaccharides from hypervirulent Klebsiella pneumoniae, are described. Their combination with polymyxin B shows no cytotoxicity in vitro and is highly effective in combating K. pneumoniae infection in vivo. Comprehensive mechanistic studies have revealed that antimicrobial activity proceeds via a multimodal mechanism. Initially, lipid nanoparticles disrupt polysaccharides, then outer and inner membranes are destabilized and destroyed by polymyxin B, resulting in synergistic cell lysis. This novel lipidic nanoparticle system shows tremendous promise as a highly effective antimicrobial treatment targeting multidrug-resistant Gram-negative pathogens.

Structural, rheological properties and antioxidant activities analysis of the exopolysaccharide produced by Rhizobium leguminosarum bv. viciae VF39.

Microbial exopolysaccharide is an eco-friendly and non-toxic biopolymeric materials widely used in various industrial fields such as pharmaceutical, food and cosmetics based on its structural, rheological and physiochemical properties. A microbial exopolysaccharide (VF39-EPS) was directly isolated from Rhizobium leguminosarum bv. viciae VF39. Structural analysis using FTIR and 2D NMR spectroscopy confirmed the complete chemical structures of VF39-EPS as 3-hydroxybutanoylglycan with octasaccharide repeating units containing two pyruvyl, two acetyl, and one 3-hydroxybutanoyl group. VF39-EPS exhibited thermal stability up to 275 °C and showed characteristic rheological behaviors of structural fluid with weak gel-like properties above 4 % the aqueous solution, suggesting VF39-EPS as a potential effective thickener or hydrogel scaffolder. Flow behavior tests validated broad stability at a wide range of both pHs from 2 to 12 and temperatures from 25 to 75 °C, and even in the presence of various salts. Furthermore, VF39-EPS showed excellent antioxidant effects of 78.5 and 62.4 % (n = 3, p < 0.001) in DPPH scavenging activity and hydroxyl radical scavenging activity, respectively. Therefore, those structural, rheological and antioxidant properties suggest that VF39-EPS could be one of the excellent biomaterial candidates for cosmetic, food and pharmaceutical industries based on its characteristic rheological behaviors in various condition and excellent antioxidant activity.

Marine versus Non-Marine Bacterial Exopolysaccharides and Their Skincare Applications.

Bacteria are well-known to synthesize high molecular weight polysaccharides excreted in extracellular domain, which constitute their protective microenvironment. Several bacterial exopolysaccharides (EPS) are commercially available for skincare applications in cosmetic products due to their unique structural features, conferring valuable biological and/or textural properties. This review aims to give an overview of bacterial EPS, an important group of macromolecules used in cosmetics as actives and functional ingredients. For this purpose, the main chemical characteristics of EPS are firstly described, followed by the basics of the development of cosmetic ingredients. Then, a focus on EPS production, including upstream and downstream processes, is provided. The diversity of EPS used in the cosmetic industry, and more specifically of marine-derived EPS is highlighted. Marine bacteria isolated from extreme environments are known to produce EPS. However, their production processes are highly challenging due to high or low temperatures; yield must be improved to reach economically viable ingredients. The biological properties of marine-derived EPS are then reviewed, resulting in the highlight of the challenges in this field.

Multiple Bio-Actives Loaded Gellan Gum Microfibers from Microfluidics for Wound Healing.

Wound healing, known as a fundamental healthcare issue worldwide, has been attracting great attention from researchers. Here, novel bioactive gellan gum microfibers loaded with antibacterial peptides (ABPs) and vascular endothelial growth factor (VEGF) are proposed for wound healing by using microfluidic spinning. Benefitting from the high controllability of microfluidics, bioactive microfibers with uniform morphologies are obtained. The loaded ABPs are demonstrated to effectively act on bacteria at the wound site, reducing the risk of bacterial infection. Besides, sustained release of VEGF from microfibers helps to accelerate angiogenesis and further promote wound healing. The practical value of woven bioactive microfibers is demonstrated via animal experiments, where the wound healing process is greatly facilitated because of the excellent circulation of air and nutritious substances. Featured with the above properties, it is believed that the novel bioactive gellan gum microfibers would have a remarkable effect in the field of biomedical application, especially in promoting wound healing.

Physicochemical characterizations, α-amylase inhibitory activities and inhibitory mechanisms of five bacterial exopolysaccharides.

Inhibiting pancreatic α-amylase activity can decrease the release rate of glucose, thereby delaying postprandial blood glucose. This study aimed to investigate the physicochemical properties and porcine pancreatic α-amylase (PPA) inhibitory activities of five bacterial exopolysaccharides (EPSs). We also aimed to analyze the differences of their inhibitory activities, exploring the inhibition mechanism between EPSs and PPA. Five EPSs had a low molecular weight (55-66 kDa), which were mainly composed of mannose and glucose with total content exceeding 86 %. The IC50 values of five EPSs (0.162-0.431 mg/mL) were significantly lower than that of acarbose (0.763 mg/mL), indicating that the inhibitory effects of five EPSs on PPA were stronger than acarbose, especially the EPS from Bacillus subtilis STB22 (BS-EPS). Moreover, BS-EPS was a mixed-type inhibitor, whereas other EPSs were noncompetitive inhibitors of PPA. Five EPSs quenched the fluorophore of PPA by the mixed quenching or apparent static quenching. Interestingly, BS-EPS showed stronger binding affinity to PPA than other EPSs. It can be speculated that EPSs with low molecular weight, high carboxylic acid content, and α-glycosidic bond exhibited high PPA inhibitory activity. These results suggest that BS-EPS can effectively inhibit PPA activity and has potential applications in reducing postprandial hyperglycemia.