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Bacterial glucans have aroused increasing interest in commercial applications in the food and pharmaceutical sectors. A number of bacterial glucans have been reported over recent decades, and their structure, production, and functional properties have been extensively studied. In this paper, we review recent researches on bacterial glucans, with emphasis on the production, physical and chemical properties, and the new developments in food, biomedical, pharmaceutical, and other industrial applications.

Salecan is a novel water-soluble glucan produced by Agrobacterium sp. ZX09. It has potential application as a food additive with a unique chemical composition and excellent physicochemical properties. The objective of this study was to investigate the acute and subchronic toxicity of Salecan. The oral LD50 of Salecan in ICR mice was greater than 3000 mg/kg body weight. In the subchronic study, ICR mice (10/sex/group) were fed diets containing 0%, 1.0%, 2.5% and 5.0% of Salecan (weight/weight) for 13 weeks. Based on the results from the subchronic study, the overall health, body weight gain, food consumption and clinical pathology parameters were comparable between the groups feed Salecan and the control. No dose-related effects were observed in the treated animals. The only exception was the observation that blood glucose in female mice fed Salecan was lower than in the control group. In addition, the fecal matter from Salecan fed mice exhibited increased water content versus the control animals. The no observed adverse effect level (NOAEL) of 14478 mg/kg body weight/day was determined. The results from this study support the conclusion that Salecan is non-toxic at the levels tested and does not pose a risk to human health when used in food., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Purpose: Methotrexate (MTX) is a widely used cancer chemotherapy agent. The efficacy of MTX is often limited by serious side effects, such as intestinal mucositis. The aim of this study was to evaluate the protective effect of water-soluble β-glucan salecan on MTX-induced intestinal toxicity in mice.Methods: Intestinal mucositis was induced in C57BL/6 mice by intraperitoneal injection of MTX for two consecutive days. Mice were orally administrated with saline or salecan for 6 days before MTX injection and continued to the end of the study. Several histological and biochemical parameters were measured in the jejunum.Results: Orally administration of salecan improved the severity of intestinal mucositis in a dose-dependent manner, as evidenced by the well-maintained mucosal architecture and body weight in salecan-treated groups. Salecan treatment inhibited MTX-induced oxidative stress and effectively scavenged free radicals both in vitro and in vivo. Metabolomics analysis revealed that salecan treatment reversed the intestinal metabolic profiling changes in mice with MTX-induced mucositis. Salecan treatment modulated the innate immunity through the regulation of TLR and Dectin1 expression in the jejunum, thus protecting mice from MTX-induced intestinal damage.Conclusions: Salecan has potential advantages in the treatment of MTX-induced intestinal mucositis, and its protective effect is mainly attributed to its antioxidant and immunomodulatory properties. [ABSTRACT FROM AUTHOR]

As a water-soluble extracellular β-glucan produced by Agrobacterium sp. ZX09, Salecan has an excellent toxicological profile and exerts multiple physiological effects. The aims of the present study were to investigate the protective effects of a Salecan diet in the well-defined dextran sulphate sodium (DSS) model of experimental murine colitis and to elucidate the mechanism involved in its effects with special attention being paid to its effect on the production of TNF-α, a primary mediator involved in the inflammatory response. Male C57BL/6J mice were fed a diet supplemented with either 4 or 8 % Salecan for 26 d and DSS was administered to induce acute colitis during the last 5 d of the experimental period. Several clinical and inflammatory parameters as well as mRNA expression of TNF-α and Dectin-1 were evaluated. The results indicated that the dietary incorporation of Salecan attenuated the severity of DSS colitis as evidenced by the decreased disease activity index, reduced severity of anaemia, attenuated changes in colon architecture and reduced colonic myeloperoxidase activity. This protection was associated with the down-regulation of TNF-α mRNA levels, which might derive from its ability to increase Dectin-1 mRNA levels. In conclusion, the present study suggests that Salecan contributes to the reduction of colonic damage and inflammation in mice with DSS-induced colitis and holds promise as a new, effective nutritional supplement in the management of inflammatory bowel disease. [ABSTRACT FROM PUBLISHER]

Salecan is a recently identified water-soluble viscous extracellular β-1,3-d-glucan polysaccharide from an Agrobacterium species. It is a high-molecular-mass polymer (about 2 × 106Da) and composed of a linear chain of glucosyl residues linked through a repeat unit of seven β-(1,3) and two α-(1,3) glucosidic bonds. In the present study, we examined the effects of dietary Salecan fed at 2 and 5 % in a high-fat diet (64 % energy) in C57BL/6J mice. After 6 weeks, mice fed 2 and 5 % Salecan had significantly lower body weight, fat mass and percentage of body fat mass compared with those fed a high-fat cellulose (control) diet. Both the Salecan groups significantly and dose-dependently improved glucose tolerance, with a 9 and 26 % reduction of glucose AUC, respectively. Liver and adipose tissue weights were also significantly decreased by the Salecan treatment. Supplementation with 5 % Salecan led to lower serum TAG, total cholesterol (TC) and HDL-cholesterol (52, 18 and 19 %, respectively) and lower hepatic TAG by 56 % and TC by 22 % compared with the high-fat cellulose control group. Dietary Salecan intake caused an obvious elevation of fat in the faeces. Supplementation with Salecan disturbed bile acid-promoted emulsification and reduced the size of emulsion droplets in vitro. These results indicate that Salecan decreases fat absorption, improves glucose tolerance and has biologically important, dose-related effects on reducing high-fat diet-induced obesity. [ABSTRACT FROM PUBLISHER]

Vulvovaginal candidiasis (VVC) is one of the most common infections in women. The purpose of this study was to evaluate the ability of a water-soluble β-glucan salecan to protect against Candida albicans (C. albicans) vaginal infection. The model was reproduced with intravaginal inoculation of yeast blastoconidia in pseudoestrus mice. We found that mice that received salecan (0.5 mg per mouse) after infection had 85% fewer CFU than infected mice given saline. Compared with the C. albicans group, salecan reduced the migration of polymorphonuclear neutrophils (PMNs) in the vagina, decreased mRNA levels of cytokines IL23 , IL22 , IL17a , and IL17f , anti-candidal genes S100a8 and S100a9 and C. albicans pattern recognition receptor Dectin1. The analysis for vaginal microbial community composition at different taxa levels revealed that the bacterial flora composition in the vagina of the salecan-treated mice was similar to that of the uninfected mice, and distinguished from the infected mice. The vaginal lavages from the salecan treated group had more Enterococcus and its metabolite lactate. Our results suggest salecan might be a potential therapeutic agent for vaginal infection of C. albicans. [ABSTRACT FROM AUTHOR]

Xyloglucans and mixed-linkage β-glucans are the major components of hemicelluloses in lignocellulosic biomass. In this study, a novel β-1,4-glucanase Pgl5A belonging to the glycoside hydrolase family 5 subfamily 4 (GH5_4), was identified from Paenibacillus sp. S09. Pgl5A is a 70.9-kDa protein containing an N-terminal GH5_4 module, a carbohydrate-binding module (CBM)_X2 and a CBM3. Full-length Pgl5A and its CBM deletion mutants Pgl5A∆C and Pgl5A-CD were expressed in E. coli. All three enzymes showed maximal activity at 55 °C and pH 4.5–5.0, and possessed similar activity toward xyloglucan, barley β-glucan, and lichenan. Deletion of the CBM modules can improve thermostability and acid-tolerant properties of Pgl5A. Circular dichroism (CD) and intrinsic fluorescence spectroscopy analysis verified that C-terminus truncation improves the enzyme acid-tolerant properties. Homology modeling and CD spectra indicated that Pgl5A has an architectural (β/α) 8 fold of GH5_4 enzymes. The catalytic efficiency (k cat / K m) of Pgl5A toward xyloglucan, but not mixed-linkage β-glucan, was reduced due to C-terminus truncation. TLC and LC-MS analysis showed that Pgl5A cleaves xyloglucan and mixed-linkage β-glucan into a series of xyloglucan oligosaccharides and gluco-oligosaccharides, respectively. The favorable enzymatic characteristics and high catalytic activities toward both xyloglucan and mixed-linkage β-glucan make Pgl5A a promising candidate for biotechnological industrial applications. [ABSTRACT FROM AUTHOR]

Salecan is a linear, macromolecular (1 → 3)-β-D-glucan that shows prebiotic potential. In this study stabilization effect of Salecan on the structure of set yogurt was investigated by means of rheological analysis and microscopic observation. Results indicated that Salecan aqueous solution showed a weak gel-like structure, and phase transition happened when the temperature increased above 42.5 °C. Addition of 0.5% (w/v) Salecan improved anti-shear ability and temperature stability of the modified yogurt (YogSal) in the tested temperature range (5°C-40 °C) according to viscosity, thixotropy, and oscillation analyses. Besides, the water holding capacity of yogurt after adding Salecan along with sucrose (5% w/v) was significantly increased from 38.6% to 83.9% ( p  < 0.01). Fluorescence microscopic images illustrated that fat granules were more stable in YogSal than in plain yogurt. Microstructure of yogurt was visualized by the scanning electron microscopy. The extra three-dimensional network consisting of strings that anchored the casein micelles appeared when Salecan was applied in yogurt. The string-like conformation strengthened the structure of yogurt gels. These results suggest that Salecan is a potential stabilizer for yogurt production by fortifying the microstructure of yogurt gels. [ABSTRACT FROM AUTHOR]

Salecan is a novel water-soluble extracellular-glucan produced by a new kind of salt-tolerant strain Agrobacterium sp. ZX09 and can be applied in food and medicine industries. In this work, Salecan (Sal) was incorporated into poly(vinyl alcohol) (PVA) to prepare novel Sal/PVA hybrid hydrogels by repeated freeze–thaw processing. Physicochemical and biological characteristics of the hydrogels were investigated to evaluate their potential as cell adhesion materials. By increasing the Salecan content in the hybrid hydrogels, their swelling capacity increased notably, while the compressive modulus decreased. Observed by SEM, Sal/PVA hydrogels had a homogeneous porous structure. The degradation rate of the hydrogels can be controlled by tailoring the composition ratio of Sal/PVA. Furthermore, cells could adhere well on the surface of Sal/PVA hydrogels. In conclusion, these results make Sal/PVA hydrogels attractive materials for biomedical applications. [ABSTRACT FROM AUTHOR]

Abstract: Salecan is a novel soluble glucan produced by Agrobacterium sp. ZX09, displaying the ability to inhibit pancreatic amylase and reduce postprandial glucose. The research here provides an investigation of the rheological properties of Salecan solution over a wide range of shear rate (0.001–1000 s−1), frequency (0.1–100 rad/s), concentrations (0.3%, 0.5%, 1.0% and 1.5%), temperature (5–95 °C) and pH (1.0–13.0). The power law model well described the rheological behavior of the solutions, in the shear-thinning region, with high determination coefficients, R 2. Salecan solutions showed a non-Newtonian viscosity behavior at all concentrations and temperatures. The solutions exhibited excellent stability below 55 °C. Viscosities were not affected after being frozen (−20 °C). Over a wide pH range from 6.0 to 12.0, the viscosity almost kept invariant. With increasing frequency, the storage and loss moduli G′ and G″ of Salecan solution increased and complex viscosities decreased continuously, which showed an elastic behaviour. All data indicated that Salecan has excellent rheological properties and could be utilized in food industry as a new source of thickening agent. [Copyright &y& Elsevier]

Abstract: A salt-tolerant strain Agrobacterium sp. ZX09 produced a high molecular mass, water-soluble extracellular polysaccharide (EPS) composed of d-glucose. By examining periodate oxidation, 1H NMR and 13C NMR spectra, it was proven that the EPS consisted of the following repeating unit: →3)-β-d-Glcp-(1→3)-[β-d-Glcp-(1→3)-β-d-Glcp-(1→3)]3-α-d-Glcp-(1→3)-α-d-Glcp-(1→. In vitro the EPS was indigestible by α-amylase, and strongly inhibited pancreatic α-amylase activity. Fasting mice fed on the EPS failed to increase blood glucose levels. Experimental diets containing the EPS suppressed steep increase in blood glucose concentration. These results suggest that the novel water-soluble glucan could be potentially useful for decreasing absorption of dietary carbohydrate and postprandial blood glucose level. [ABSTRACT FROM AUTHOR]