NMR Analyses of the Enzymatic Degradation End-Products of Diabolican: The Secreted EPS of Vibrio diabolicus CNCM I-1629

Diabolican, or HE800, is an exopolysaccharide secreted by the non-pathogenic Gram-negative marine bacterium Vibrio diabolicus (CNCM I-1629). This polysaccharide was enzymatically degraded by the Bacteroides cellulosilyticus WH2 hyaluronan lyase. The end products were purified by size-exclusion chromatography and their structures were analyzed in depth by nuclear magnetic resonance (NMR). The oligosaccharide structures confirmed the possible site of cleavage of the enzyme showing plasticity in the substrate recognitions. The production of glycosaminoglycan-mimetic oligosaccharides of defined molecular weight and structure opens new perspectives in the valorization of the marine polysaccharide diabolican

Evaluation of the Efficiency of Ethanol Precipitation and Ultrafiltration on the Purification and Characteristics of Exopolysaccharides Produced by Three Lactic Acid Bacteria

Exopolysaccharides (EPS) produced by three Lactic Acid Bacteria strains, Lactococcus lactis SLT10, Lactobacillus plantarum C7, and Leuconostoc mesenteroides B3, were isolated using two methods: ethanol precipitation (EPS-ETOH) and ultrafiltration (EPS-UF) through a 10 KDa cut-off membrane. EPS recovery by ultrafiltration was higher than ethanol precipitation for Lactococcus lactis SLT10 and Lactobacillus plantarum C7. However, it was similar with both methods for Leuconostoc mesenteroides B3. The monomer composition of the EPS fractions revealed differences in structures and molar ratios between the two studied methods. EPS isolated from Lactococcus lactis SLT10 are composed of glucose and mannose for EPS-ETOH against glucose, mannose, and rhamnose for EPS-UF. EPS extracted from Lactobacillus plantarum C7 and Leuconostoc mesenteroides B3 showed similar composition (glucose and mannose) but different molar ratios. The molecular weights of the different EPS fractions ranged from 11.6±1.83 to 62.4±2.94 kDa. Molecular weights of EPS-ETOH fractions were higher than those of EPS-UF fractions. Fourier transform infrared (FTIR) analysis revealed a similarity in the distribution of the functional groups (O-H, C-H, C=O, -COO, and C-O-C) between the EPS isolated from the three strains

Use of almond shell as food ingredient

Almond shell is a major waste from the almond processing industry. Its feasibility as natural source of health-promoting components was examined. The by-product was fractionated under basic conditions following an easy scale-up process. The chemical composition of the recovered fraction and its antioxidant and antidiabetic properties were evaluated. Novel information regarding the chemical composition of the polysaccharides was also obtained. Almond shell is formed by lignin-carbohydrate complexes possessing antioxidant properties and capacity to inhibit α-glucosidase. According to our knowledge, this is the first time α-glucosidase inhibitory activity of a lignin-carbohydrate complex is reported. Biscuits containing non-caloric sweetener soluble (2.5%) and insoluble (5.6%) dietary fiber, natural antioxidants (1.34 mg of gallic acid equivalents/g) and α-glucosidase inhibitors (1 g of biscuit–1 mg of acarbose) achieved a high sensorial score (7.2 out of 9) when almond shell was incorporated to them. The application of a fraction from almond shell containing lignin-polysaccharides complexes as food ingredient in biscuit formulations for people with particular nutritional requirements is feasible and new.The present research was funded by AGL2014-57239-R project and The Ministry of Higher Education And Scientifc Research, Tunisia. Martinez-Saez, N. thanks the Autonomous University of Madrid (U.A.M) for her FPI-predoc fellowship.Peer reviewe

Medium-throughput profiling method for screening polysaccharide-degrading enzymes in complex bacterial extracts

International audiencePolysaccharides are the most abundant and the most diverse renewable materials found on earth. Due to the stereochemical variability of carbohydrates, polysaccharide-degrading enzymes - i.e. glycoside hydrolases and polysaccharide lyases - are essential tools for resolving the structure of these complex macromolecules. The exponential increase of genomic and metagenomic data contrasts sharply with the low number of proteins that have ascribed functions. To help fill this gap, we designed and implemented a medium-throughput profiling method to screen for polysaccharide-degrading enzymes in crude bacterial extracts. Our strategy was based on a series of filtrations, which are absolutely necessary to eliminate any reducing sugars not directly generated by enzyme degradation. In contrast with other protocols already available in the literature, our method can be applied to any panel of polysaccharides having known and unknown structures because no chemical modifications are required. We applied this approach to screen for enzymes that occur in Pseudoalteromonas carrageenovora grown in two culture conditions. (c) 2012 Elsevier B.V. All rights reserved

Structure of an Amino Acid-Decorated Exopolysaccharide Secreted by a Vibrio alginolyticus Strain

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Structure of the Exopolysaccharide Secreted by a Marine Strain Vibrio alginolyticus

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Water-soluble polysaccharides and hemicelluloses from almond gum: Functional and prebiotic properties

International audienceThis paper describes the extraction of polysaccharides (AGP) and hemicelluloses (AGH) from almond gum by hot water and alkaline solution, respectively. Structural and functional properties of the extracted polymers were then determined. For this purpose, infrared spectroscopy was first used to characterize functional groups of both polymers. The molecular weights of AGP and AGH were then determined using high performance size exclusion chromatography, resulting in 5.72×106g/mol and 5.39×106g/mol, respectively. Monosaccharide composition of both polymers was assessed using gas chromatography. The analysis of the functional properties showed that AGP and AGH had high water-holding (11.36g/g and 6.3g/g, respectively) and fat-binding (5.35g/g and 2.7g/g, respectively) capacities, with good emulsion properties. The prebiotic properties of AGP and AGH were then evaluated using in vitro fermentation by Bifidobacterium adolescentis and Lactobacillus acidophilus. Both polymers showed suitability for in vitro fermentation, suggesting thus their prebiotic nature. The obtained results demonstrated the promising potential of AGP and AGH for different applications in food industry

Structure of the Polysaccharide Secreted by Vibrio alginolyticus CNCM I-5035 (Epidermist 4.0 TM )

International audienceVibrio alginolyticus (CNCM I-5035) secretes an exopolysaccharide used as ingredient in cosmetic industry under the trademark Epidermist 4.0 TM. It is appreciated for its ability to improve the physical and chemical barrier functions of the skin by notably increasing the keratinocyte differentiation and epidermal renewal. Composition analyses and in depth characterization of the polysaccharides as well as oligosaccharides obtained by mild acid hydrolyses revealed that it was composed of a repetition unit of three residues: d-galactose (d-Gal), d-N-acetylglucosamine (GlcNAc) and l-N-acetylguluronic acid, of which 30% (M/M) was acetylated in position 3. The complete structure of the polysaccharide was resolved giving the repetition unit: [→3)-α-d-Gal-(1→4)-α-l-GulNAcA/α-l-3OAc-GulNAcA-(1→4)-β-d-GlcNAc-(1→]

Structure of an Amino Acid-Decorated Exopolysaccharide Secreted by a Vibrio alginolyticus Strain

Vibrio alginolyticus (CNCM I-4994) secretes an exopolysaccharide that can be used as an ingredient in cosmetic applications. The structure was resolved using chromatography and one- and two-dimensional NMR spectroscopy experiments. The results show that the carbohydrate backbone is made of two residues: d-galacturonic acid and N-acetyl-d-glucosamine (GlcNac), which together constitute a tetrasaccharide repetition unit: [→3)-α-d-GalA-(1→4)-α-d-GalA-(1→3)-α-d-GalA-(1→3)-β-GlcNAc(1→]. Two amino acids, alanine and serine, are linked to GalA residues via amido linkages. The position and the distribution of the amino acids were characterized by two-dimensional NMR spectroscopy. To our knowledge, this is the first description of a structure for a marine exopolysaccharide decorated with an amino acid

Structural data and biological properties of almond gum oligosaccharide: Application to beef meat preservation

International audienceEnzymatic hydrolysis of almond gum generates low molecular weight oligosaccharides (OAG) with a yield of 33.5%. The generated oligosaccharides were purified and identified. OAG analyses show that the most prominent residues were galactose and arabinose with traces of xylose, rhamnose, glucose and mannose. The glycosyl linkage positions were analyzed using gas chromatography–mass spectrometry showing a main chain composed of galactose units [→3)-Gal-(1→] branched mainly with arabinose residues [Ara-(1→]. The antioxidant and antimicrobial activities of OAG were investigated. As regards the in vitro antioxidant activities, the OAG showed a high total antioxidant activity (347 μg ascorbic acid equivalent/mL), an important DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging activity (IC50 = 0.64 mg/mL) and a high reducing capacity (RP0.5AU = 3.6 mg/mL). Furthermore, OAG had a high antimicrobial activity against Salmonella thyphimirium, Bacillus cereus, Actinomycetes sp, Klebsiella pneumoniae, Escherichia coli, Alternaria alternate and Candidat albicans. Finally, OAG efficiency was tested using 0.5%; 0.75% and 1% concentrations in beef meat preservation. Microbial growth and lipid oxidation were monitored during 9 days at 4 °C. The results showed significant inhibitions (p < 0.05) of lipid oxidation and microbial growth in ground beef meat containing OAG