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Aims: Heavy metal pollution seriously threatens human health and ecological environment. Due to high efficiency and excellent development prospect, adsorption technology has attracted worldwide attention. It is significant to develop renewable adsorbents with excellent adsorption performance., Scope: In this study, the Pb 2+ and Zn 2+ adsorption capacity of Ca-alginate immobilized and free (without immobilization) Leu. citreum B-2 extracellular polysaccharides (EPS) was investigated. Isotherm and kinetic models were used to evaluate the adsorption performance. The adsorbents were characterized by SEM, FT-IR and XPS spectroscopy., Conclusions: The maximum biosorption of Pb 2+ 269.54 and Zn 2+ 49.88 mg/g was achieved with immobilized EPS. Thermodynamic studies showed that the adsorption of Pb 2+ and Zn 2+ on EPS was a spontaneous and feasible process, and the adsorption properties of EPS were exothermic for lead and endothermic for zinc. All the adsorption processes conformed to the pseudo-second-order model and Langmuir adsorption isotherm model, indicating that the adsorption was mainly chemisorption taken placed on single adsorption surface. SEM results showed that the surface of EPS become denser after adsorption. FTIR and XPS analysis indicated that the adsorption mechanism mainly involved the complexation reaction and ion exchange of functional groups such as CO, O-C-O, -COOH and C-OH., (Copyright © 2021. Published by Elsevier B.V.)

Objective: Although the extracellular polysaccharides have been analyzed in the previous period, the biochemical, enzymological characters and stimulation and inhibition effect on glucansucrase are not fully understood., Results: After three steps purification, salting out, DEAE-Sepharose and Sephadex G-75, the final specific activity was 264.84 U/mg protein with 4.31-fold. The SDS-PAGE analysis of fraction gave a single band 170.35 kDa in the stained gel. The active band was analyzed with LC-MS/MS to identify glucansucrase. The highest coverage rate of dextransucrase from Leu. citreum (ACY92456.2) was 55.60%, the results were speculated that the glucansucrase secreted from Leu. citreum B-2 may be a novel glucansucrase. The purified enzyme was optimally active at 20-30 °C and pH 6.0-8.0. Metal ions K + , Na + , Ca 2+ , Mn 2+ , Mg 2+ , and Cr + had an apparent stimulating effect on enzyme activity, especially in divalent ions Ca 2+ and Mn 2+ , the residual activities were higher than 200%. In a reverse, Hg + , acetonitrile, SDS, salt, and guanidine expressed inhibition effect on enzyme residual activity. The K M and V max were detected to be 4.82 mM and 0.97 U/mg, respectively., Conclusion: All these data collectively indicate that B-2 glucansucrase is a novel one, which have good properties and may applied to new food areas.

The fermentation conditions for exopolysaccharides (EPS) with a highly branched structure extracted from Leuconostoc citreum B-2 were optimized by response surface methodology (RSM). The results showed that under the optimal fermentation conditions of sucrose, yeast extract and pH of 99.80 g/L, 5.94 g/L and 6.12, respectively, the B-2 EPS yield was 59.33 ± 1.34 g/L, which was 5.93 times greater than that from the initial nonoptimized conditions. Chemical composition analysis showed that the carbon, hydrogen, nitrogen and sulfur contents of the B-2 pure EPS (P-EPS) were 39.05 ± 0.25%, 7.19 ± 0.08%, 0.72 ± 0.03% and 0%, respectively. The content of uronic acid was high, reaching 20.94 ± 6.30%. B-2 EPS had certain 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl (·OH), superoxide anion (O 2- ), hydrogen peroxide (H 2 O 2 ), nitroso radical (NO 2- ) scavenging abilities and reducing power. The degradation temperature of the B-2 EPS was 313 °C, indicating that B-2 EPS have high thermal stability. The emulsification effect on vegetable oils was better than that of hydrocarbons. The EPS produced by Leu. citreum B-2 was activated in different concentrations of sucrose-supplemented skimmed milk, which caused the skimmed milk to have different degrees of solidification. Moreover, B-2 EPS promoted the growth of probiotic bacteria, especially Lactobacillus delbrueckii., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A water-soluble exopolysaccharide (EPS)-producing strain YF32 was isolated from soybean paste, which was then identified as Leuconostoc pseudomesenteroides. After culturing the strain in Man-Rogosa-Sharpe (MRS) medium containing 5% sucrose at 30°C for 48h, the EPS was purified, and a yield of 12.5g/L was achieved. The weight-average molecular weight (Mw) was 5.54×10 6 Da by high-performance size-exclusion chromatography (HPSEC). The structural characterization of the purified EPS was determined by gas chromatography (GC), Fourier transform infrared (FT-IR), 1 H, 13 C nuclear magnetic resonance (NMR) spectroscopy. The results demonstrated that the exopolysaccharide was glucan with a peak, a linear backbone composed of consecutive α-(1→6)-linked d-glucopyranose units. No branching was observed in the dextran structure. The degradation temperature (Td) of EPS was 307.62°C, which suggested that dextran exhibited high thermal stability. YF32 dextran also showed high water solubility and emulsibility. All results suggested that dextran has the potential to be applied in food fields as a food additive., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A strain Leuconostoc citreum B-2 was isolated from homemade fermentation product of pineapple and its polysaccharide yield was 28.3g/L after cultivating the strain in Man-Rogosa-Sharpe (MRS) medium with 75g/L sucrose. The exopolysaccharide (EPS) was characterized by gas chromatography (GC), Fourier-transform infrared (FT-IR) spectra, high-performance size-exclusion chromatography (HPSEC), nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscope (SEM) analysis in present study. The monosaccharide composition of EPS was glucose and molecular weight was 3.77×10 6 Da. FT-IR and NMR spectra revealed that the B-2 EPS was composed of 75% α-(1→6) linked d-glucopyranose units existing in the main chain with 19% α-(1→3) branching and only a few α-(1→2) branching. The SEM of the dried EPS appeared irregular sheets with glittering surface and compact structure. Water solubility index and water holding capacity of B-2 EPS were 80% and 450%, respectively. All the mentioned characteristics suggested that the EPS has a potential application in the food, cosmetic and pharmaceuticals industry., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A water-souble exopolysaccharide (EPS) produced by Leuconostoc pseudomesenteroides XG5 from homemade wine was investigated. The EPS yield of 35.5g/L was achieved at 30°C for 48h in De Man-Rogosa-Sharpe (MRS) medium containing 12.5% sucrose. The EPS was a dextran composed exclusively of glucose and the molecular weight was 2.6×10 6 Da. Fourier transform infrared spectra and nuclear magnetic resonance spectra revealed that the EPS was a dextran containing D-glucose residues in a linear chain with consecutive α-(1→6) linkages. Scanning electron microscopy of the EPS appeared a highly branched and porous structure. Rheological studies showed that the EPS had higher viscosity in 0.1M KCl solution, at lower temperature, or at acidic pH. Thermal gravimetric analysis and differential scanning calorimetric indicated that the EPS had excellent thermal stability with a degradation temperature of 313.80°C and melting point at 274.14°C. Water solubility index and water holding capacity of XG5 dextran were 90.2% and 412% respectively. The results suggest that L. pseudomesenteroides XG5 might be widely used in the production of linear dextran which has potential to serve as natural agent applied in food and other fields., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A water-soluble exopolysaccharide (EPS) was produced by Leuconostoc ctireum NM105 from homemade manchurian sauerkraut. After culturing the strain in Man-Rogosa-Sharpe medium containing 5% sucrose at 25°C for 48h, the EPS was purified and a yield of 23.5g/L was achieved. The EPS consisted exclusively of glucose and the weight-average molecular weight was 1.01×10(8)Da. The structural characterization of the purified EPS determined by FT-IR, (1)H, (13)C and two-dimensional NMR spectroscopy demonstrated that the glucan contained α-(1→6)-linked d-glucopyranose units, 2,6-linked d-glucopyranose units and terminal α-d-glucopyranose units at a ratio of 1:1:1. The microstructure of the dried dextran appeared a sheet-like smooth glittering and highly branched surface. The NM105 dextran showed high water solubility and excellent water retention. All the results suggested that the highly α-(1→2) branched dextran might have the potential to serve as valuable polymers applied in foods, cosmetics and other fields., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Sugarcane molasses is an agricultural by-product containing sucrose. In this study, the exopolysaccharide (M-EPS) produced by Leuconostoc citreum B-2 in molasses-based medium was characterized, optimized, and its application in set yogurt was investigated. The structure analysis, including gel permeation chromatography, Fourier transform infrared spectroscopy, and nuclear magnetic resonance, revealed that the M-EPS was a linear dextran composed of D-glucose units, which were linked by α-(1→6) glycosidic bonds with 19.3% α-(1→3) branches. The M-EPS showed a lower molecular weight than that produced from sucrose. The M-EPS was added into the set yogurt, and then the water holding capacity, pH, and microstructure of set yogurt were evaluated. Compared with the controls, the addition of M-EPS improved the water holding capacity and reduced the pH of set yogurt. Meanwhile, the structure of the three-dimensional network was also observed in the set yogurt containing M-EPS, indicating that M-EPS had a positive effect on the stability of set yogurt. The results provide a theoretical basis for the cost-effective utilization of sugarcane molasses. [ABSTRACT FROM AUTHOR]

BACKGROUND Type 1 diabetes is an autoimmune disease that results in the specific destruction of insulin‐producing beta cells in the pancreas. The aim of this study was to investigate the mechanism of exopolysaccharide from Leuconostoc pseudomesenteroides XG5 (XG5 EPS) against type 1 diabetes. RESULTS: Long‐term drench of XG5 EPS delayed the onset of autoimmune diabetes and had fewer islets with high‐grade infiltration (an insulitis score of 3 or 4) than untreated NOD mice. Oral administration of 50 mg kg−1 d−1 XG5 EPS increased the insulin and glucagon‐like peptide‐1 (GLP‐1) levels of serum, stimulated GLP‐1 secretion and upregulated gcg mRNA expression of colon in NOD mice. Moreover, oral administration of 50 mg kg−1 d−1 XG5 EPS significantly increased total short‐chain fatty acids levels in the colon contents, especially those of acetic acid and butyric acid. In NCI‐H716 cells, 500 and 1000 μmol L−1 sodium butyrate promoted the secretion of GLP‐1 and upregulated the mRNA expression of gcg and PC3, while XG5 EPS and sodium acetate did not stimulate the GLP‐1 secretion. Therefore, long‐term drench of XG5 EPS delayed the onset of autoimmune diabetes, which may be directly correlated with the increase of butyrate in the colon of NOD mice. CONCLUSION: Long‐term drench of 50 mg kg−1 d−1 XG5 EPS promoted the expression and secretion of GLP‐1 by increasing the production of butyric acid, thereby delaying T1D onset in NOD mice. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Exopolysaccharide from Leuconostoc pseudomesenteroides XG5 (XG5 EPS) is a linear dextran that is built by glucose units via α-1,6 glycosidic bond. The primary objective of this study was to investigate the yield of XG5 EPS and its application in set yogurt. In laboratory scale, the culture conditions of XG5 EPS production were optimized using the L9 (33) orthogonal test. Here, the optimized yield of XG5 EPS was 26.02 g/L under the conditions of 100 g/L sucrose, initial pH 7.0, 25°C incubation, and 100 rpm for 36 h in a shaking flask. Based on the optimized parameters of laboratory scale, a pilot fed-batch fermentation was performed in a 50-L bioreactor with an adjusted agitation speed of 20 rpm. The XG5 EPS yield reached 40.07 g/L in fed-batch fermentation, which was 54% higher than that achieved in laboratory scale. In addition, XG5 EPS was added into set yogurt to investigate its effect on the stability of set yogurt. Our data demonstrated that the XG5 EPS improved the water-holding capacity, texture profile, and viscosity of set yogurt during cold storage compared with the controls. In particular, addition of 0.5% XG5 EPS increased the structure of 3-dimensional network of set yogurt, which eventually improved the physical stability of the set yogurt. Overall, this study provided new insights for exploring the pilot scale production and application of dextran. [Display omitted] [ABSTRACT FROM AUTHOR]

• PC EPS is a dextran consisting of consecutive α-(1→6)-linked D-glucopyranose units. • The dextran polymer showed an irregular sheet structure and porous surface. • The dextran displayed heat tolerance and high viscosity at low pH properties. • The dextran could coagulate sucrose-supplemented milk. • The dextran has potential applications in food and dairy processing. An exopolysaccharide (EPS)-producing bacterial strain, PC, was isolated from pickled Chinese cabbage and identified as Leuconostoc pseudomesenteroides. EPS yield was up to 30.5 g/L when bacteria were cultivated in Man-Rogosa-Sharpe (MRS) medium containing 5% sucrose at 30°C for 48 h. Further analysis by gas chromatography, high performance size exclusion chromatography, and nuclear magnetic resonance revealed that the EPS consisted of glucose with α-(1→6) linkages and had a molecular weight of 3.13 × 106 Da. Scanning-electron microscopy demonstrated an irregular sheet structure and porous surface, and lumps with an average height of 77.803 nm were observed by atomic force microscopy. Physical-chemical analysis showed that the EPS exhibited excellent thermal stability and possessed high viscosity at high concentration, low temperature and acidic pH, making it promising to be used in thermal processed foods and fermentation of acidic food products. Milk solidification test also suggested the promising potential for application as a dairy and food additive since the EPS could activate the solidification of sucrose-supplemented milk. Taken together, this study provides a commercial guidance for the practical application of PC EPS in food industry and other areas. [ABSTRACT FROM AUTHOR]

An exopolysaccharide (EPS) was produced by Leuconostoc pseudomesenteroides DRP-5 isolated from homemade wine. The EPS was obtained with ethanol extraction, which was further purified by chromatography of Sephadex G-100 to get a purified fraction. The monosaccharide composition of the EPS was glucose, and its molecular weight (Mw) was 6.23 × 10 6 Da, as determined by gas chromatography (GC) and high-performance size-exclusion chromatography (HPSEC). Fourier transform infrared spectra (FT-IR) and nuclear magnetic resonance spectra (NMR) showed that the EPS was a linear glucan with α-(1→6)-linked glucosidic bonds. The water holding capacity (WHC), water solubility index (WSI) and emulsifying activity (EA) of DRP-5 EPS were 296.76 ± 18.93%, 98.62 ± 3.57% and 87.22 ± 2.18%, respectively. DRP-5 EPS have a higher degradation temperature of 278.36 °C, suggesting high thermal stability of the EPS. Also, DRP-5 EPS was found to have moderate 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, hydroxyl radical, superoxide anion radical, 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) radical, Fe 2+ scavenging activities and reducing power. All these characteristics suggest that DRP-5 EPS might have potential applications in the pharmaceutical, cosmetic and food industries. [ABSTRACT FROM AUTHOR]