Structure Of Exopolysaccharide Research Articles

Application of exopolysaccharides synthesized by Xanthomonas campestris in an efficient separation system of refractory chalcopyrite and molybdenite

Bacterial polysaccharides get an abundance of attention owing to their distinctive biological activity and promising applications. Recent research found that the specificity of the molecular structure of exopolysaccharides (EPS) can be used to accomplish selective regulation of the physicochemical properties of mineral surfaces. The development and application of novel microbial EPS as a flotation reagent for chalcopyrite and molybdenite separation possesses a promising development prospect. Consequently, we attempted to create effective and sustainable molybdenite depressants in this work by optimizing the strain's fermentation settings and identifying the molecular structure of the generated EPS. Fermentation condition tests revealed patterns of influence of fermentation parameters on EPS yield, the viscosity average molecular weight, and biomass during the fermentation process, and optimized the optimal fermentation conditions. Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and ion chromatography (IC) analyses clarified the structure of the EPS in terms of monosaccharide composition, glycosidic bonding, and functional groups. Mixed mineral flotation tests proved that a low dosage of polysaccharide reagent (100 mg/L) at pH 10 effectively inhibited molybdenite and achieved separation targets of 21.96% Cu and 2.63% Mo in the concentrate, with separation efficiencies (SE) of 72.67% and 55.78% for Cu and Mo, respectively.

Challenges and opportunities in elucidating the structures of biofilm exopolysaccharides: A case study of the Pseudomonas aeruginosa exopolysaccharide called Pel.

Biofilm formation protects bacteria from antibiotic treatment and host immune responses, making biofilm infections difficult to treat. Within biofilms, bacterial cells are entangled in a self-produced extracellular matrix that typically includes exopolysaccharides. Molecular-level descriptions of biofilm matrix components, especially exopolysaccharides, have been challenging to attain due to their complex nature and lack of solubility and crystallinity. Solid-state nuclear magnetic resonance (NMR) has emerged as a key tool to determine the structure of biofilm matrix exopolysaccharides without degradative sample preparation. In this review, we discuss challenges of studying biofilm matrix exopolysaccharides and opportunities to develop solid-state NMR approaches to study these generally intractable materials. We specifically highlight investigations of the exopolysaccharide called Pel made by the opportunistic pathogen, Pseudomonas aeruginosa. We provide a roadmap for determining exopolysaccharide structure and discuss future opportunities to study such systems using solid-state NMR. The strategies discussed for elucidating biofilm exopolysaccharide structure should be broadly applicable to studying the structures of other glycans.

Temperature stress improved exopolysaccharide yield from Tetragenococcus halophilus: Structural differences and underlying mechanisms revealed by transcriptomic analysis

This study aimed to enhance exopolysaccharide production by Tetragenococcus halophilus, and results showed that low temperature (20 °C) significantly improved exopolysaccharide production. Based on the analysis of batch fermentation kinetic parameters, a temperature-shift strategy was proposed, and the exopolysaccharide yield was increased by 28 %. Analysis of the structure of exopolysaccharide suggested that low temperature changed the molecular weight and monosaccharide composition. Transcriptomic analysis was performed to reveal mechanisms of low temperature improving exopolysaccharide production. Results suggested that T. halophilus regulated utilization of carbon sources through phosphotransferase system and increased the expression of key genes in exopolysaccharide biosynthesis to improve exopolysaccharide production. Meanwhile, metabolic pathways involved in glycolysis, amino acids synthesis, two-component system and ATP-binding cassette transporters were affected at low temperature. Results presented in this paper provided a theoretical basis for biosynthetic pathway of exopolysaccharide in T. halophilus and aided to strengthen its production and application in many areas.

Detection of exopolysaccharides (algD, pelF, and pslD) genes in burn wound Pseudomonas aeruginosa isolates

Abstract Background: Pseudomonas aeruginosa biofilm is an essential component of virulence that plays a significant role in antimicrobial resistance and chronic burn wound infections. Objective: This study aimed to investigate the biofilm formation capacity of P. aeruginosa isolated from chronic burn wound from January to May 2022 by biochemical and molecular techniques. Materials and Methods: Quantification of biofilm was performed based on tube method for local isolates of P. aeruginosa after growing on brain heart Broth. The genes encoding exopolysaccharides (algD, pelF, and pslD) were targeted by using conventional polymerase chain reaction (PCR). Results: The results showed that 92.6% of isolates were biofilm former, interestingly 68% of isolates were considered as strong former comparing with other biofilm categories. Gel electrophoresis result of PCR products presented clear bands for algD and psID genes with percentages (96%) and (3.7%) respectively. However, there was no PCR product for pelf gene among all isolates. Conclusion: The prevalence of algD, the large operon necessary for alginate production, was high among P. aeruginosa biofilm producer in this study and it can be an essential agent in the pathogenicity of P. aeruginosa burn wound infections comparing with other biofilm genes (pelF and pslD) of exopolysaccharide structure.

Application of exopolysaccharide directionally synthesized by Xanthomonas campestris as the green selective depressant for the clean flotation of talc: Statistical optimization and mechanism analysis

During froth flotation, the more non-polar, friable talc (Mg3(Si2O5)2(OH)2) usually adheres to the surface of sulfide ore and floats up, causing difficulties in flotation separation and subsequent industrial treatment. Microbial flotation as a green separation method avoids chemical contamination due to the limited selectivity and high agent consumption of the currently used inhibitors. Recent studies have found that exopolysaccharides produced by Xanthomonas campestris (X.c) could be used as inhibitors for the efficient flotation separation of talc from chalcopyrite. Therefore, this paper is the first attempt to optimize the molecular structure of exopolysaccharides and the optimal culture parameters of this strain to synthesize a green depressant for efficient flotation of talc, and also to explore in depth the mechanism of its selective inhibition of talc. Results of fermentation condition experiments and Fourier transform infrared analysis showed that the exopolysaccharides with the presence of polar groups (—OH and –COOH) significantly inhibited the floatability of talc. 1H Nuclear magnetic resonance further identified the active components of polar groups in the polysaccharide structure as hydroxyl groups, glucuronic acid, and pyruvic acid. Furthermore, the fermentation parameters were optimized by response surface methodology and increased the yield of exopolysaccharides by 5.55 g/L compared with before optimization. Flotation experiments on mixed ore confirmed the excellent selective inhibition of the synthesized exopolysaccharide at pH 7 and a 60 mg/L concentration. The contact angle test showed a significant decrease from 65.04° to 51.77° on the talc surface after the reaction with 60 mg/L concentration of exopolysaccharides. Atomic force microscopy characterization directly revealed the multilayer adsorption of exopolysaccharides on the talc surface, as well as a high coverage of 50.88%.

Production and Characterization of a Novel Exopolysaccharide from Ramlibacter tataouinensis.

The current study examines the desiccation-resistant Ramlibacter tataouinensis TTB310T as a model organism for the production of novel exopolysaccharides and their structural features. This bacterium is able to produce dividing forms of cysts which synthesize cell-bound exopolysaccharide. Initial experiments were conducted on the enrichment of cyst biomass for exopolysaccharide production under batch-fed conditions in a pilot-scale bioreactor, with lactate as the source of carbon and energy. The optimized medium produced significant quantities of exopolysaccharide in a single growth phase, since the production of exopolysaccharide took place during the division of the cysts. The exopolysaccharide layer was extracted from the cysts using a modified trichloroacetic acid method. The biochemical characterization of purified exopolysaccharide was performed by gas chromatography, ultrahigh-resolution mass spectrometry, nuclear magnetic resonance, and Fourier-transform infrared spectrometry. The repeating unit of exopolysaccharide was a decasaccharide consisting of ribose, glucose, rhamnose, galactose, mannose, and glucuronic acid with the ratio 3:2:2:1:1:1, and additional substituents such as acetyl, succinyl, and methyl moieties were also observed as a part of the exopolysaccharide structure. This study contributes to a fundamental understanding of the novel structural features of exopolysaccharide from a dividing form of cysts, and, further, results can be used to study its rheological properties for various industrial applications.

Improving the biological properties of Fomes fomentarius MG835861 exopolysaccharide by bioincorporating selenium into its structure

Selenium (Se) is one of the essential elements for human health, where Se-containing compounds can prevent cancer and reduce mortality by regulating of the cell cycle and apoptosis. Exopolysaccharides from Fomes fomentarius have been used in traditional medicine to treat cancer. It appears that the combination of Se and fungal polysaccharides may be more effective. The effect of adding Na2SeO3 to the culture medium of the Iranian medicinal fungus F. fomentarius is investigated in this study. Adding 20 mg/L Na2SeO3 to the culture medium changed the F. fomentarius morphology and improved the structure of exopolysaccharides. Several methods, including FTIR, EDS, and ICP-OES, confirmed the presence of Se in the exopolysaccharides of F. fomentarius. The results demonstrated that the addition of Na2SeO3 increased the antibacterial activity against S.aureus (60%) and antioxidant activity (17.4%) significantly (p < 0.05). The cytotoxicity of these exopolysaccharides against 5637, A549, and KYSE30 cancer cells was also significantly increased (p < 0.05), and the viability of EPS-Se treated 5637 cells reached less than 10% after 72 h. Finally, F. fomentarius Se-polysaccharides can be used as a dietary supplement.

Temperature mediates metabolism switching of Bacillus sp. ZT-1: Analysis of the properties and structure of exopolysaccharides

Microorganism was very sensitive to external temperature change, which also affected its normal metabolism and secretion. Low temperature exopolysaccharides (LT-EPS) and normal temperature exopolysaccharides (NT-EPS) secreted by Bacillus sp. ZT-1 mediated by temperature were studied in this paper. The total carbohydrate in the LT-EPS and NT-EPS were found to be 82.54 ± 2.56 % and 94.23 ± 1.59 % (w/w). The High Performance Liquid Chromatography (HPLC) revealed the mannose and galacturonic acid accounted for 45.52 and 23.49 % in LT-EPS, respectively. In like manner, mannose and galacturonic acid contained 43.99 and 25.24 % in NT-EPS.One-dimensional nuclear magnetic resonance (NMR) revealed the connection mode of sugar chains. NT-EPS exhibited higher viscosity, better emulsification properties and the larger molecular weight than LT-EPS. Scanning electron microscopy (SEM) showed that LT-EPS was sheet-like with sugar chain branches while NT-EPS was showed as network structure. Furthermore, the 2812 differentially expressed genes (DEGs) were analyzed by Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment and located 739 biological pathways. Finally, transcriptome analysis revealed differences in gene expression of the pentose phosphate pathway of carbohydrate metabolism might be the main reason for this difference.

Structure and chemical composition of exopolysaccharides of frost-damaged sugar beet

In this research paper, development of a procedure of isolation of exopolysaccharides from frost-damaged beet and an analysis of structural and chemical composition of polymers isolated from sugar beet of different origin are presented. Total acid hydrolysis degradation integrated with HPAEC-ED analysis has been utilized to confirm the monomeric composition of the separated polysaccharides. The implementation of NMR spectral analysis and SEC chromatography of the structure of exopolysaccharides has been investigated. The results demonstrate that the chemical composition and structure of exopolysaccharides depend on their origin. Typical exopolysaccharides from Central European beet roots consist mainly of glucose monomers – and they have low branched structure – about 90% of α-1,6 linkage which is typical for dextran. The exopolysaccharides isolated from Swedish beet are characterized by 50–60% fructose monomers. They contain only about 65% α-1,6 linkages. Exopolysaccharides extracted from various origin beet differ in average molecular mass. The molecular distribution is not normal.

Anti-biofilm activity of LC-MS based Solanum nigrum essential oils against multi drug resistant biofilm forming P. mirabilis.

Urinary tract infections are second most important diseases worldwide due to the increased amount of antibiotic resistant microbes. Among the Gram negative bacteria, P. mirabilis is the dominant biofilm producer in urinary tract infections next to E. coli. Biofilm is a process that produced self-matrix of more virulence pathogens on colloidal surfaces. Based on the above fact, this study was concentrated to inhibit the P. mirabilis biofilm formation by various in-vitro experiments. In the current study, the anti-biofilm effect of essential oils was recovered from the medicinal plant of Solanum nigrum, and confirmed the available essential oils by liquid chromatography-mass spectroscopy analysis. The excellent anti-microbial activity and minimum biofilm inhibition concentration of the essential oils against P. mirabilis was indicated at 200 µg/mL. The absence of viability and altered exopolysaccharide structure of treated cells were showed by biofilm metabolic assay and phenol–sulphuric acid method. The fluorescence differentiation of P. mirabilis treated cells was showed with more damages by confocal laser scanning electron microscope. Further, more morphological changes of essential oils treated cells were differentiated from normal cells by scanning electron microscope. Altogether, the results were reported that the S. nigrum essential oils have anti-biofilm ability.

Assembly of Bacterial Capsular Polysaccharides and Exopolysaccharides.

Polysaccharides are dominant features of most bacterial surfaces and are displayed in different formats. Many bacteria produce abundant long-chain capsular polysaccharides, which can maintain a strong association and form a capsule structure enveloping the cell and/or take the form of exopolysaccharides that are mostly secreted into the immediate environment. These polymers afford the producing bacteria protection from a wide range of physical, chemical, and biological stresses, support biofilms, and play critical roles in interactions between bacteria and their immediate environments. Their biological and physical properties also drive a variety of industrial and biomedical applications. Despite the immense variation in capsular polysaccharide and exopolysaccharide structures, patterns are evident in strategies used for their assembly and export. This review describes recent advances in understanding those strategies, based on a wealth of biochemical investigations of select prototypes, supported by complementary insight from expanding structural biology initiatives. This provides a framework to identify and distinguish new systems emanating from genomic studies.

Study of the chemical structure of exopolysaccharide produced from streptomycete and its effect as an attenuate for antineoplastic drug 5-fluorouracil that induced gastrointestinal toxicity in rats

Chemotherapeutic medications, including 5 – fluorouracil (5FU), are the same old technique to most cancers and are associated with numerous peripheral toxicities. We investigated exopolysaccharide (EPSST) produced from the isolated streptomycete of the Mediterranean Sea for the capability to lower the severity of mucositis in vivo. The streptomycete was isolated from Mediterranean Sea sediment from the beaches of Port Said Governorates, Egypt and identified morphologically, physiologically, and biochemically and confirmed by molecularly 16S rDNA analysis. The EPSST was extracted from the supernatant of streptomycete by using 4 volumes chilled ethanol and then the functional groups, MW, and chemical evaluation have been detected via Fourier-transform infrared (FTIR), and high-performance liquid chromatography (HPLC). In addition, antioxidant activity was measured through the usage of 2, 2-diphenyl-1-picrylhydrazyl (DPPH). Thirty-two male rats (180–200 g) were randomly divided into a control group (normal saline), intraperitoneal injection of 5-fluorouracil (5-FU, 150 mg/kg), normal rats were treated with EPSST and 5-FU + EPSST group. These groups were continued up to the day of sacrifice (28 days post treatments). The isolated strain became recognized based totally on 16S rDNA sequence as Streptomyce sp. with accession number SAMN08349905. The chemical evaluations of EPSST were galacturonic, glucose, galactose, mannose, and arabinose with a relative ratio of 2.1: 1: 5.37: 1.62: 1.29 individually, with an average molecular weight (Mw) 9.687 × 103 g/mol. Also, the EPSST contained uronic acid (16%) and sulfate (12.149%) and no protein was detected. EPSST inhibited the DPPH radical activity. The findings of this study propose that EPSST inhibits 5-FU-induced mucositis through adjustment of oxidative stress, apoptosis, inflammatory factors, activation of antioxidant enzymes. The clinical administration of EPSST may recover the chemotherapy-induced intestinal dysfunction, consequently increasing the clinical efficiency of chemotherapy. In addition, the administration of EPSST reduced 5-FU-induced histopathological incongruities such as neutrophil infiltration, loss of cellular integrity, and villus and crypt distortion. The clinical administration of EPSST may recover the chemotherapy-induced intestinal dysfunction, consequently increasing the clinical efficiency of chemotherapy.

A novel structure of exopolysaccharide produced by a plant-derived lactic acid bacterium Lactobacillus paracasei IJH-SONE68.

A lactic acid bacterium Lactobacillus paracasei IJH-SONE68, which was isolated from a fig leaf by our group, was found to produce both acidic and neutral exopolysaccharides (EPSs). The nuclear magnetic resonance analysis demonstrates that the former EPS is composed primarily of mannose, and the latter one consists of the α-1, 6-linked glycan chains made of N-acetylglucosamine (GlcNAc). The presence of α-1, 6-linked GlcNAc polysaccharide is first reported in prokaryotes. Furthermore, to reveal the EPS-biosynthetic gene organization in the IJH-SONE68 strain, in the present study, we determined the whole-genome sequence.

Abundant production of exopolysaccharide by EAEC strains enhances the formation of bacterial biofilms in contaminated sprouts

ABSTRACTEnteroaggregative E. coli (EAEC) is associated with food-borne outbreaks of diarrhea and growth faltering among children in developing countries. A Shiga toxin-producing EAEC strain of serotype O104:H4 strain caused one of the largest outbreaks of a food-borne infection in Europe in 2011. The outbreak was traced to contaminated fenugreek sprouts, yet the mechanisms whereby such persistent contamination of sprouts could have occurred are not clear. We found that under ambient conditions of temperature and in minimal media, pathogenic Shiga toxin-producing EAEC O104:H4 227-11 and non-Shiga toxin-producing 042 strains both produce high levels of exopolysaccharide structures (EPS) that are released to the external milieu. The exopolysaccharide was identified as colanic acid (CA). Unexpectedly, Shiga-toxin producing EAEC strain 227-11 produced 3-6-fold higher levels of CA than the 042 strain, suggesting differential regulation of the CA in the two strains. The presence of CA was accompanied by the formation of large biofilm structures on the surface of sprouts. The wcaF-wza chromosomal locus was required for the synthesis of CA in EAEC 042. Deletion in the glycosyltransferase wcaE gene abolished the production of CA in 042, and resulted in diminished adherence to sprouts when co-cultured at ambient temperature. In conclusion, this work suggests that copious production of CA may contribute to persistence of EAEC in the environment and suggests a potential explanation for the large Shiga toxin-producing EAEC outbreak in 2011.

Exopolysaccharides from Marine and Marine Extremophilic Bacteria: Structures, Properties, Ecological Roles and Applications.

The marine environment is the largest aquatic ecosystem on Earth and it harbours microorganisms responsible for more than 50% of total biomass of prokaryotes in the world. All these microorganisms produce extracellular polymers that constitute a substantial part of the dissolved organic carbon, often in the form of exopolysaccharides (EPS). In addition, the production of these polymers is often correlated to the establishment of the biofilm growth mode, during which they are important matrix components. Their functions include adhesion and colonization of surfaces, protection of the bacterial cells and support for biochemical interactions between the bacteria and the surrounding environment. The aim of this review is to present a summary of the status of the research about the structures of exopolysaccharides from marine bacteria, including capsular, medium released and biofilm embedded polysaccharides. Moreover, ecological roles of these polymers, especially for those isolated from extreme ecological niches (deep-sea hydrothermal vents, polar regions, hypersaline ponds, etc.), are reported. Finally, relationships between the structure and the function of the exopolysaccharides are discussed.

Comparative Study on Structure of Exopolysaccharide and Capsular Polysaccharide Produced by Southern Ocean Origin Pseudoalteromonas sp. MB-16

A comparative study on the basic structural characteristics of exopolysaccharide (EPS) and capsular polysaccharide (CPS) produced by the Southern Ocean (Indian Sector) origin Pseudoalteromonas sp. MB-16 has been conducted. It has a higher production rate of EPS as compared to that of CPS and the maximum production rate is 0.7 g/l when glucose is the carbon source. Elemental analysis and infrared spectroscopic study have given a brief compositional insight on the EPS and CPS produced by the marine bacterium, whereas scanning electron micrographs have revealed the morphological structure of Pseudoalteromonas sp. derived EPS and CPS. Both the polysaccharides show significant thermal stability as confirmed by thermogravimetric analysis. In all the experiments, Pseudoalteromonas sp. derived EPS and CPS have given similar results when compared to standard bacterial polysaccharides dextran and guar gum. This present study gave an important preliminary idea about the nature of bacterial polysaccharides produced by the Southern Ocean (Indian Sector) origin microbe.

Extracellular DNA and lipoteichoic acids interact with exopolysaccharides in the extracellular matrix of Streptococcus mutans biofilms

Streptococcus mutans-derived exopolysaccharides are virulence determinants in the matrix of biofilms that cause caries. Extracellular DNA (eDNA) and lipoteichoic acid (LTA) are found in cariogenic biofilms, but their functions are unclear. Therefore, strains of S. mutans carrying single deletions that would modulate matrix components were used: eDNA – ∆lytS and ∆lytT; LTA – ∆dltA and ∆dltD; and insoluble exopolysaccharide – ΔgtfB. Single-species (parental strain S. mutans UA159 or individual mutant strains) and mixed-species (UA159 or mutant strain, Actinomyces naeslundii and Streptococcus gordonii) biofilms were evaluated. Distinct amounts of matrix components were detected, depending on the inactivated gene. eDNA was found to be cooperative with exopolysaccharide in early phases, while LTA played a larger role in the later phases of biofilm development. The architecture of mutant strains biofilms was distinct (vs UA159), demonstrating that eDNA and LTA influence exopolysaccharide distribution and microcolony organization. Thus, eDNA and LTA may shape exopolysaccharide structure, affecting strategies for controlling pathogenic biofilms.

Evaluation of the yield, molar mass of exopolysaccharides, and rheological properties of gels formed during fermentation of milk by Streptococcus thermophilus strains St-143 and ST-10255y

The yield and chemical structures of exopolysaccharides (EPS) produced by many strains of Streptococcus thermophilus have been characterized. However, the kinetics (or production profile) for EPS during milk fermentation is not clear. In this study, we investigated whether any differences existed in the yield and molar mass of EPS when milk was fermented at the same acidification rate by 2 strains of S. thermophilus(St-143 and ST-10255y). The type of EPS produced by these 2 strains is different. Milk samples were analyzed for EPS concentration every 30 min during a fermentation period of 270 min (final pH 4.5) by using a modified quantification method, which was faster and validated for its recovery of added EPS. Rheological properties of milks during fermentation were also analyzed using small-strain dynamic oscillatory rheology. For the determination of molar mass, EPS extracts were isolated by ultrafiltration of whey obtained during fermentation of milk to pH values 5.2, 4.9, 4.7, and 4.5, and molar mass was analyzed using size-exclusion chromatography-multi-angle laser light scattering. During fermentation, both strains appeared to start producing significant amounts of EPS after about ∼150 min, which corresponded to pH ∼5.3, which was close to the point of gelation. During the remainder of the fermentation process (150-270 min), the EPS concentration from strains St-143 and ST-10255y significantly increased from 30 to 72 mg/L and from 26 to 56 mg/L, respectively. The quantity of EPS recovered by our modified method was estimated to represent ∼60% of the total EPS added to milk. The molar mass of EPS produced by both strains appeared to slightly decrease during fermentation. At pH 5.2, EPS from St-143 and ST-10255y had molar masses of 2.9 × 106 and 1.4 × 106 g/mol, respectively, which decreased to 1.6 × 106 and 0.8 × 106 g/mol, respectively, when the pH of milk was 4.5. Distinct differences were apparent in the rheological properties of gels fermented by the 2 strains. At the end of fermentation, St-143 fermented milk had weaker gels with storage modulus (G') value at pH 4.6 of 26 Pa, whereas gels made with ST-10255y were stiffer with a G' value at pH 4.6 of 82 Pa. For St-143 gels, maximum loss tangent (LTmax) values were higher (0.50) and occurred earlier (at a higher pH value) than the LTmax values (0.46) for gels from ST-10255y strain. Because the fermentation conditions were identical for both strains, the observed changes in rheological properties could be due to the differences in chemical structures and molar mass of the EPS produced by these 2 S. thermophilus strains.

Molecular weight and helix conformation determine intestinal anti-inflammatory effects of exopolysaccharide from Schizophyllum commune

Intestinal anti-inflammatory activities of exopolysaccharide from S. commune were assessed using dextran sulfate sodium (DSS)-induced colitis in mice model. The changes of molecular weight (MW), atomic force microscope morphology, X-ray diffraction, particle size distribution, and viscosity were recorded after sonication treatment. The results indicated that the triple helical structure of exopolysaccharide was dissociated into single helical structure and random coiled structure by ultrasonication via breaking of inter- and intramolecular hydrogen bonds. The medium (936kDa) and high MW (1437kDa) exopolysaccharide had the mixture of triple helix and single helix conformation, while the low MW (197kDa) exopolysaccharide exhibit random coiled conformation. The intestinal anti-inflammatory activity study showed that oral administration of medium and high MW (1437kDa) exopolysaccharide significantly recovered DSS-induced colitis in inflamed tissues and reduced inflammation induced infiltration of macrophages. These results showed that medium (936kDa) and high MW (1437kDa) exopolysaccharide had intestinal anti-inflammatory activity. The intestinal anti-inflammatory activity of exopolysaccharide was related to helical structure and molecular weight.

Revealing the Compact Structure of Lactic Acid Bacterial Heteroexopolysaccharides by SAXS and DLS

Molecular structures of exopolysaccharides are required to understand their functions and the relationships between the structure and physical and rheological properties. Small-angle X-ray scattering and dynamic light scattering were used in conjunction with molecular modeling to characterize solution structures of three lactic acid bacterial heteroexopolysaccharides (HePS-1, HePS-2, and HePS-3). Values of radius of gyration RG, cross-sectional radius of gyration RXS, approximate length L, and hydrodynamic diameter were not directly proportional to the molar mass and indicated the HePSs adopted a compact coil-like rather than an extended conformation. Constrained molecular modeling of 15000 randomized HePS-1 conformers resulted in five best-fit structures with R factor of 3.9-4.6% revealing random coil-like structure. Φ and Ψ angle analysis of glycosidic linkages in HePS-1 structures suggests Galf residues significantly influence the conformation. Ab initio scattering modeling of HePS-2 and HePS-3 gave excellent curve fittings with χ2 of 0.43 and 0.34 for best-fit models, respectively, compatible with coil-like conformation. The findings disclose solution behavior of HePS relevant for their interactions with biomacromolecules, for example, milk proteins.