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Flavobacterium strains exert a substantial influence on roots and leaves of plants. However, there is still limited understanding of how the specific interactions between Flavobacterium and their plant hosts are and how these bacteria thrive in this competitive environment. A crucial step in understanding Flavobacterium - plant interactions is to unravel the structure of bacterial envelope components and the molecular features that facilitate initial contact with the host environment. Here, we have revealed structure and properties of the exopolysaccharides (EPS) produced by Flavobacterium sp. Root935. Chemical analyses revealed a complex and interesting branched heptasaccharidic repeating unit, containing a variety of sugar moieties, including Rha, Fuc, GlcN, Fuc4N, Gal, Man and QuiN and an important and extended substitution pattern, including acetyl and lactyl groups. Additionally, conformational analysis using molecular dynamics simulation showed an extended hydrophobic interface and a distinctly elongated, left-handed helicoidal arrangement. Furthermore, properties of the saccharide chain, and likely the huge substitution pattern prevented interaction and recognition by host lectins and possessed a low immunogenic potential, highlighting a potential role of Flavobacterium sp. Root935 in plant-microbial crosstalk.

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Microalgae are photosynthetic organisms that can produce biomolecules with industrial interest, including exopolysaccharides (EPS). Due to their structural and compositional diversity, microalgae EPS present interesting properties that can be considered in cosmetic and/or therapeutic areas. Seven microalgae strains from three different lineages, namely Dinophyceae (phylum Miozoa), Haptophyta, and Chlorophyta, were investigated as EPS producers. All strains were found to be EPS producers, though the highest EPS yield was obtained for Tisochrysis lutea, followed by Heterocapsa sp. (126.8 and 75.8 mg L−1, respectively). Upon assessment of the polymers’ chemical composition, significant contents of unusual sugars, including fucose, rhamnose, and ribose, were found. Heterocapsa sp. EPS stood out due to its high content of fucose (40.9 mol%), a sugar known to confer biological properties to polysaccharides. The presence of sulfate groups (10.6–33.5 wt%) was also noticed in the EPS produced by all microalgae strains, thus contributing to the possibility that these EPS might have biological activities worth exploring.(AU)

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This work focused on the development of porous scaffolds based on biocomposites comprising two biodegradable and biocompatible biopolymers: a terpolyester, poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (PHBHVHHx), and the bacterial polysaccharide FucoPol. The PHBHVHHx terpolymer was composed of 3-hydroxybutyrate (55 wt%), 3-hydroxyvalerate (21 wt%), and 3-hydroxyhexanoate (24 wt%). This hydrophobic polyester has low crystallinity and can form elastic and flexible films. Fucopol is a fucose-containing water-soluble polysaccharide that forms viscous solutions with shear thinning behavior and has demonstrated emulsion-forming and stabilizing capacity and wound healing ability. Emulsion-templating was used to fabricate PHA-based porous structures in which FucoPol acted as a bioemulsifier. Compared with the scaffolds obtained from emulsions with only water, the use of FucoPol aqueous solutions resulted in structures with improved mechanical properties, namely higher tensile strength (4.4 MPa) and a higher Young's Modulus (85 MPa), together with an elongation at break of 52%. These features, together with the scaffolds' high porosity and pore interconnectivity, suggest their potential to sustain cell adhesion and proliferation, which is further supported by FucoPol's demonstrated wound healing ability. Therefore, the developed PHBHVHHx:FucoPol scaffolds arise as innovative porous bioactive structures with great potential for use in tissue engineering applications.

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In this study, the exopolysaccharide (EPS) from Lactiplantibacillus plantarum (HMX2) was isolated from Chinese Northeast Sauerkraut. Its effects on juvenile turbot were investigated by adding different concentrations of HMX2-EPS (C: 0 mg/kg, H1: 100 mg/kg, H2: 500 mg/kg) to the feed. Compared with the control group, HMX2-EPS significantly improved the growth performance of juvenile turbot. The activities of antioxidant enzymes, digestive enzymes, and immune-related enzymes were significantly increased. HMX2-EPS could also increase the secretion of inflammatory factors and enhance the immune response of turbot by regulating the IFN signal transduction pathway and exhibit stronger survival rates after the A. hydrophila challenge. Moreover, HMX2-EPS could improve the diversity of intestinal microbiota in juvenile fish, increase the abundance of potential probiotics, and reduce the abundance of pathogenic bacteria. The function of gut microbes in metabolism and the immune system could also be improved. All results showed better effects with high concentrations of HMX2-EPS. These results indicated that HMX2-EPS supplementation in the diet could promote growth, improve antioxidant activity, digestive capacity, and immunity capacity, and actively regulate the intestinal microbiota of juvenile turbot. In conclusion, this study might provide basic technical and scientific support for the application of L. plantarum in aquatic feed.

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Microalgae are photosynthetic organisms that can produce biomolecules with industrial interest, including exopolysaccharides (EPS). Due to their structural and compositional diversity, microalgae EPS present interesting properties that can be considered in cosmetic and/or therapeutic areas. Seven microalgae strains from three different lineages, namely Dinophyceae (phylum Miozoa), Haptophyta, and Chlorophyta, were investigated as EPS producers. All strains were found to be EPS producers, though the highest EPS yield was obtained for Tisochrysis lutea, followed by Heterocapsa sp. (126.8 and 75.8 mg L-1, respectively). Upon assessment of the polymers' chemical composition, significant contents of unusual sugars, including fucose, rhamnose, and ribose, were found. Heterocapsa sp. EPS stood out due to its high content of fucose (40.9 mol%), a sugar known to confer biological properties to polysaccharides. The presence of sulfate groups (10.6-33.5 wt%) was also noticed in the EPS produced by all microalgae strains, thus contributing to the possibility that these EPS might have biological activities worth exploring.

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In this study, the novel exopolysaccharide (EPS) produced by the marine bacterium Alteromonas macleodii Mo 169 was used as a stabilizer and capping agent in the preparation of selenium nanoparticles (SeNPs). The synthesized nanoparticles were well dispersed and spherical with an average particle size of 32 nm. The cytotoxicity of the EPS and the EPS/SeNPs bio-nanocomposite was investigated on human keratinocyte (HaCaT) and fibroblast (CCD-1079Sk) cell lines. No cytotoxicity was found for the EPS alone for concentrations up to 1 g L-1. A cytotoxic effect was only noticed for the bio-nanocomposite at the highest concentrations tested (0.5 and 1 g L-1). In vitro experiments demonstrated that non-cytotoxic concentrations of the EPS/SeNPs bio-nanocomposite had a significant cellular antioxidant effect on the HaCaT cell line by reducing ROS levels up to 33.8%. These findings demonstrated that the A. macleodii Mo 169 EPS can be efficiently used as a stabilizer and surface coating to produce a SeNP-based bio-nanocomposite with improved antioxidant activity.

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An exopolysaccharide (EPS)-producing soil bacterium was isolated and characterized using 16S rRNA as Bacillus sp. EPS003. EPS was precipitated using ethanol and % composition of total carbohydrate, and protein was determined. Monosaccharide composition was identified using thin layer chromatography (TLC), and it was found to be a levan. Fourier transform infrared (FTIR) spectrum revealed the peaks for carboxyl, hydroxyl, and amide functional groups. 1H nuclear magnetic resonance (NMR) spectrum further confirmed the presence of fructose monomer. Field emission scanning electron microscopic images (FE-SEM) revealed porous and amorphous characteristics of EPS which was further confirmed with broad peaks in X-ray diffraction (XRD) spectrum. Elemental composition was determined using energy-dispersive X-ray analysis (EDAX). Thermogravimetric analysis (TGA) of EPS resulted in a residual mass of 33.81% at 548 °C indicating high thermal stability. In addition, solubility index and water-holding capacity of EPS were found to be 56% and 264%, respectively, making EPS suitable for various applications. Further, antioxidant potential of EPS was studied using hydroxyl and DPPH radical scavenging assays. In vitro cytotoxicity assessment using L929 cells and SK-MEL-3 cell lines clearly indicated that the EPS produced by the novel isolate Bacillus sp. EPS003 could serve as a potential anticancer agent.

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INTRODUCTION: Exopolysaccharides (EPSs) are high-value functional biomaterials mainly produced by bacteria and fungi, with nutraceutical, therapeutic and industrial potentials. OBJECTIVES: This study sought to characterize and assess the biological properties of the EPS produced by the yeast Papiliotrema terrestris PT22AV. METHODS: After extracting the yeast's DNA and its molecular identification, the EPS from P. terrestris PT22AV strain was extracted and its physicochemical properties (structural, morphological, monosaccharide composition and molecular weight) were characterized. The EPS's in vitro biological activities and in vivo wound healing potential were also evaluated. RESULTS: The obtained EPS was water-soluble and revealed an average molecular weight (Mw) of 202 kDa. Mannose and glucose with 97% and 3% molar percentages, respectively, constituted the EPS. In vitro antibacterial activity analysis of the extracted EPS exhibited antibacterial activity (>80%) against Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis at a concentration of 2 mg/mL. The EPS showed cytocompatibility against the human fibroblast and macrophage cell lines and the animal studies showed a dose-dependent wound healing capacity of the EPS with higher wound closure at 10 mg/mL compared to negative and positive control after 14 days. CONCLUSION: The EPS from P. terrestris PT22AV could serve as a promising source of biocompatible macromolecules with potential for skin wound healing.

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The cell surface of lactic acid bacteria (LAB) plays an essential role in cell-cell and cell-host interactions. Exopolysaccharides (EPSs) are produced on the cell surface of LAB or in the surrounding medium and are considered to be in favor of the strain- specific probiotic surface characteristics. In this work, the structure features of EPS from Lacticaseibacillus paracasei S-NB were analyzed preliminarily, and the genes involved in EPS biosynthesis of S-NB strain were hypothesized and annotated, and their role in phenotypic characteristics were demonstrated by gene deletion analysis. Four mutant strains with deletion of crucial genes involved in EPS synthesis were analyzed for strain characteristics that are closely related to their ability to interact with the host intestinal epithelium cells, including strain surface characteristics and viability under the gastrointestinal stress conditions (both acid and bile stress). Furthermore, the adherence and immunomodulatory properties of wild-type S-NB and its mutant strains were compared using Caco-2 and RAW 264.7 cell lines, respectively. Taken together, the results indicated the importance of genes associated with EPS biosynthesis in L. paracasei S-NB as a determinant in strain surface characteristics and cell-host interaction, especially for S-NB_2176 (responsible for EPS polymerization) and S-NB_2175 (responsible for CpsD/CapB family tyrosine-protein kinase).

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Microbial exopolysaccharides (EPSs) are mostly produced by bacteria and fungi and have potential use in the production of biomedical products such as nutraceuticals and in tissue engineering applications. The present study investigated the in vitro biological activities and in vivo wound healing effects of EPSs produced from a Sclerotium-forming fungus (Sclerotium glucanicum DSM 2159) and a yeast (Rhodosporidium babjevae), denoted as scleroglucan (Scl) and EPS-R, respectively. EPS yields of 0.9 ± 0.07 g/L and 1.11 ± 0.4 g/L were obtained from S. glucanicum and R. babjevae, respectively. The physicochemical properties of the EPSs were characterized using infrared spectroscopy and scanning electron microscopy. Further investigations of the biological properties showed that both EPSs were cytocompatible toward the human fibroblast cell line and demonstrated  hemocompatibility. Favorable wound healing capacities of the EPSs (10 mg/mL) were also established via in vivo tests. The present study therefore showed that the EPSs produced by S. glucanicum and R. babjevae have the potential use as biocompatible components for the promotion of dermal wound healing.

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Two exopolysaccharide fractions (GL1-E1 and GL1-E2) of Lacticaseibacillus paracasei GL1 were isolated with the molecular weights of 3.9 × 105 Da and 8.2 × 105 Da, respectively. Both fractions possessed mannose, glucose, and galactose in molar ratios of 1.16:1.00:0.1, and 3.81:1.00:0.12, respectively. A structural arrangement of two fractions was proposed by methylation, one-dimensional and two-dimensional nuclear magnetic resonance experiments. The backbone of GL1-E1 consisted of →4)-α-D-Glcp(1→, →3,4)-α-D-Manp(1→, →3,6)-α-D-Manp(1→, →6)-α-D-Manp(1→, and →6)-α-D-Galp(1→ with α-D-Glcp at branching point. The backbone of GL1-E2 consisted of →4)-α-D-Glcp(1→, →3,4)-α-D-Manp(1→, →3,6)-α-D-Manp(1→, →6)-α-D-Manp(1→, →6)-α-D-Galp(1→, and →4)-ß-D-Manp(1→, and the side chain also consisted of α-D-Manp residue. In addition, the differential scanning calorimetry (DSC) analysis indicated that both GL1-E1 and GL1-E2 had good thermal stability. Furthermore, the two fractions could promote the viability of RAW264.7 cells and exert an immunomodulatory role by enhancing phagocytosis, increasing nitric oxide (NO) release and promoting the expression of cytokines.

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This work assessed the film-forming capacity of exopolysaccharides (EPS) produced by six Alteromonas strains recently isolated from different marine environments in French Polynesia atolls. The films were transparent and resulted in small colour alterations when applied over a coloured surface (ΔEab below 12.6 in the five different colours tested). Moreover, scanning electron microscopy showed that the EPS films were dense and compact, with a smooth surface. High water vapour permeabilities were observed (2.7-6.1 × 10-11 mol m-1 s-1 Pa-1), which are characteristic of hydrophilic polysaccharide films. The films were also characterised in terms of barrier properties to oxygen and carbon dioxide. Interestingly, different behaviours in terms of their mechanical properties under tensile tests were observed: three of the EPS films were ductile with high elongation at break (ε) (35.6-47.0%), low tensile strength at break (Ꞇ) (4.55-11.7 MPa) and low Young's modulus (εm) (10-93 MPa), whereas the other three were stiffer and more resistant with a higher Ꞇ (16.6-23.6 MPa), lower ε (2.80-5.58%), and higher εm (597-1100 MPa). These properties demonstrate the potential of Alteromonas sp. EPS films to be applied in different areas such as biomedicine, pharmaceuticals, or food packaging.

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Exopolysaccharide (EPS) isolated from Lactobacillus helveticus SNA12 were purified, and one fraction (SNA12-EPS) was obtained. The structure of SNA12-EPS was proposed using Fourier-transform infrared spectroscopy, gas chromatography-mass spectrometry, and nuclear magnetic resonance. Results showed that SNA12-EPS was rich in galactose and glucose with the molar ratios of 2.1:1.0, and SNA12-EPS possessed the repeat units of →3)-ß-D-Glcp-(1→3)-ß-D-Glcp-(1→4)-ß-D-Galp-(1→ with an average molecular weight of 3.81 × 105 Da. The scanning electron microscope results showed that SNA12-EPS had a tight structure with a smooth and uneven surface. Furthermore, the prebiotic potential of SNA12-EPS was performed using in vitro simulated digestion with human faecal fermentation. SNA12-EPS was not digested by digestive juice, and it could markedly regulate the gut microbiota composition by increasing the relative abundances of Parabacteroides and Blautia and decreasing the abundance of pathogenic bacteria of Fusobacterium. Additionally, SNA12-EPS improved the ability of gut microbiota to produce short-chain fatty acids.

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Soybean whey is a kind of agricultural by-product enriched with nutritional value but with low utilization. The extracellular polysaccharides secreted by lactic acid bacteria during the fermentation possess a variety of structural characteristics and beneficial properties. In this study, an exopolysaccharide (EPS) was isolated from Leuconostoc citreum 1.2461 after fermentation in optimized soybean whey-enriched 10% sucrose at 37 °C for 24 h. The water-soluble EPS-1 was obtained by DEAE-52 anion exchange chromatography, and the structural characterization of EPS-1 was investigated. The EPS-1 was homogeneous with an average molecular weight of 4.712 × 106 Da and consisted mainly of glucose. Nuclear magnetic resonance (NMR) spectrum and flourier transform infrared (FT-IR) spectrum indicated that the EPS-1 contained →3)-α-D-Glcp-(1→ and →6)-α-D-Glcp-(1→ residues. The rheological properties of EPS-1 under the conditions of changing shear rate, concentration, temperature and coexisting ions showed its pseudoplastic fluid behaviors. In addition, the EPS-1 exhibited certain scavenging activity on the ABTS radical and chelating activity on metal ions at relatively high concentrations. Furthermore, EPS-1 with a certain concentration was confirmed to have significant protective effects on yeast cell injury induced by hydrogen peroxide. This study reported the structural characteristics of exopolysaccharide from Lc. citreum 1.2461 and provides a basis for its potential application in the field of functional foods.

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Dahi is a very common and traditional fermented dairy product in Pakistan and its neighboring countries, it represents a rich source for the isolation of many new strains of lactic acid bacteria (LAB). The major objective of this study was to evaluate the probiotic potential of novel exopolysaccharide (EPS)-producing strains of S. thermophilus isolated from Dahi, sold in the local markets of Rawalpindi and Islamabad, Pakistan. In this study, 32 isolates of S. thermophilus were initially isolated from Dahi and out of these, 10 identified strains were further screened for their EPS-producing ability. Maximum EPS production was estimated for RIY strain (133.0 ± 0.06), followed by RIH4 strain (103.83 ± 0.76) and RIRT2 strain (95.77 ± 0.22), respectively. Thereafter, in vitro studies revealed that these newly identified EPS-producing strains of S. thermophilus fulfilled the basic requirements for probiotic functions; including resistance to harsh conditions of GIT, good cell surface hydrophobicity, auto-aggregation, and co-aggregation, especially against L. monocytogenes. Finally, the safety assessment displayed that these strains were also sensitive to clinical antibiotics, including vancomycin. Thus, these selected EPS strains of S. thermophilus act as potential candidates for biostabilizers in the preparation of consumer-friendly fermented probiotic milk products.

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This study evaluated the effects of probiotic Lactobacillus plantarum MC5 on the quality, antioxidant activity, and storage stability of yogurt, to determine its possible application as a starter in milk fermentation. Four groups of yogurt were made with different proportions of probiotic L. plantarum MC5 and commercial starters. The yogurt samples' rheological properties, texture properties, antioxidant activity, storage stability, and exopolysaccharides (EPS) content during storage were determined. The results showed that 2:1 and 1:1 yogurt samples (supplemented with L. plantarum MC5) attained the highest EPS content (982.42 mg/L and 751.71 mg/L) during storage. The apparent viscosity, consistency, cohesiveness, and water holding capacity (WHC) of yogurt samples supplemented with L. plantarum MC5 were significantly higher than those of the control group (p < 0.05). Further evaluation of antioxidant activity revealed that yogurt samples containing MC5 starter significantly increased in DPPH, ABTS, OH, and ferric iron-reducing power. The study also found that adding MC5 can promote the growth of Streptococcus thermophilus. Therefore, yogurt containing L. plantarum MC5 had favorable rheological properties, texture, and health effects. The probiotic MC5 usage in milk fermentation showed adequate potential for industrial application.

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The bacterium Myxococcus xanthus forms both developmental and vegetative types of biofilms. While the former has been studied on both agar plates and submerged surfaces, the latter has been investigated predominantly on agar surfaces as swarming colonies. Here we describe the development of a microplate-based assay for the submerged biofilms of M. xanthus under vegetative conditions. We examined the impacts of inoculation, aeration, and temperature to optimize the conditions for the assay. Aeration was observed to be critical for the effective development of submerged biofilms by M. xanthus, an obligate aerobic bacterium. In addition, temperature plays an important role in the development of M. xanthus submerged biofilms. It is well established that the formation of submerged biofilms by many bacteria requires both exopolysaccharide (EPS) and the type IV pilus (T4P). EPS constitutes part of the biofilm matrix that maintains and organizes bacterial biofilms while the T4P facilitates surface attachment as adhesins. For validation, we used our biofilm assay to examine a multitude of M. xanthus strains with various EPS and T4P phenotypes. The results indicate that the levels of EPS, but not of piliation, positively correlate with submerged biofilm formation in M. xanthus.

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Objectives: The quorum-sensing-inhibitory and anti-biofilm activities of the methanol extract of E. globulus leaves were determined against clinically isolated multidrug-resistant Pseudomonas aeruginosa. Methods: The preliminary anti-quorum-sensing (AQS) activity of eucalyptus was investigated against a biosensor strain Chromobacterium violaceum ATCC 12472 (CV12472) by using the agar well diffusion method. The effect of sub-minimum inhibitory concentrations (sub-MICs) of the methanol extract of eucalyptus on different quorum-sensing-regulated virulence factors, such as swarming motility, pyocyanin pigment, exopolysaccharide (EPS), and biofilm formation, against clinical isolates (CIs 2, 3, and 4) and reference PA01 of Pseudomonas aeruginosa were determined using the swarm diameter (mm)-measurement method, chloroform extraction method, phenol (5%)-sulphuric acid (concentrated) method, and the microtiter plate assay respectively, and the inhibition (%) in formation were calculated. Results: The preliminary AQS activity (violacein pigment inhibition) of eucalyptus was confirmed against Chromobacterium violaceum ATCC 12472 (CV12472). The eucalyptus extract also showed concentration-dependent inhibition (%) of swarming motility, pyocyanin pigment, EPS, and biofilm formation in different CIs and PA01 of P. aeruginosa. Conclusion: Our results revealed the effectiveness of the E. globulus extract for the regulation of quorum-sensing-dependent virulence factors and biofilm formation at a reduced dose (sub-MICs) and suggest that E. globulus may be a therapeutic agent for curing and controlling bacterial infection and thereby reducing the possibility of resistance development in pathogenic strains.

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Inflammatory bowel disease (IBD) is an autoimmune disease characterized by chronic inflammation of the gastrointestinal tract. IBD includes Crohn's disease (CD) and ulcerative colitis (UC). CD can occur in any part of the gastrointestinal tract, whereas UC mainly occurs in the colon and rectum. We previously demonstrated that a novel exopolysaccharide (EPS) produced by a plant-derived bacterium, Lactobacillus paracasei IJH-SONE68, prevents and improves the inflammation in contact dermatitis model mice via oral administration. To evaluate the preventive effect of the EPS against other inflammatory diseases, in the present study, we employed dextran sulfate sodium (DSS)-induced UC model mice. The stool consistency, hematochezia, and colonic atrophy of the mice were improved by the orally administered EPS. We also evaluated the cytokine transcription. Overexpression of the mouse macrophage inflammatory protein 2 mRNA in the colon as a functional homolog of human interleukin-8 was decreased by the orally administered EPS. However, the expression of interleukin-10, which is known as an anti-inflammatory cytokine, was stimulated in the EPS-administrated group. Based on these results, we conclude that the IJH-SONE68-derived EPS is a promising lead material for the development of drugs useful in treating inflammatory diseases such as UC.

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Yak yogurt, one of the naturally fermented dairy products prepared by local herdsmen in the Qinghai-Tibet Plateau, contains a diverse array of microorganisms. We isolated and identified a novel Streptococcus thermophilus strain, ZJUIDS-2-01, from the traditional yak yogurt. We further purified and carried out detailed structural, physiochemical, and bioactivity studies of an exopolysaccharide (EPS-3A) produced by S. thermophilus ZJUIDS-2-01. The weight-average molecular weight (Mw) of EPS-3A was estimated to be 1.38 × 106 Da by High-Performance Gel Permeation Chromatography (HPGPC). The monosaccharide analysis established its composition to be glucose, galactose, N-acetyl-D-galactosamine, and rhamnose in a ratio of 5.2:2.5:6.4:1.0. The molecular structure of EPS-3A was determined by the combination of permethylation analysis, FT-IR, and NMR spectroscopic techniques. The ζ-potential measurements indicated that EPS-3A had a pKa value of ~4.40. The DSC yielded a melting point (Tm) of 80.4 °C and enthalpy change (ΔH) of 578 J/g for EPS-3A, comparable to those of the xanthan gum (XG), a commercial EPS. EPS-3A exhibited better O/W emulsion stability and flocculating capacity than XG. Furthermore, it also demonstrated similar antioxidant activity to XG and promising in vitro antibacterial properties. This work evidenced that EPS-3A derived from S. thermophilus ZJUIDS-2-01 holds the potential for food and industrial applications.

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