Optimization, purification, characterization and antioxidant activity of an extracellular polysaccharide produced by Paenibacillus polymyxa SQR-21

The optimization, purification and characterization of an extracellular polysaccharide (EPS) from a bacterium Paenibacillus polymyxa SQR-21 (SQR-21) were investigated. The results showed that SQR-21 produced one kind of EPS having molecular weight of 8.96 × 10⁵ Da. The EPS was comprised of mannose, galactose and glucose in a ratio of 1.23:1.14:1. The ratio of monosaccharides and glucuronic acid was 7.5:1. The preferable culture conditions for EPS production were pH 6.5, temperature 30 °C for 96 h with yeast extract and galactose as best N and C sources, respectively. The maximum EPS production (3.44 g L⁻¹) was achieved with galactose 48.5 g L⁻¹, Fe³⁺ 242 μM and Ca²⁺ 441 μM. In addition, the EPS showed good superoxide scavenging, flocculating and metal chelating activities while moderate inhibition of lipid peroxidation and reducing activities were determined. These results showed the great potential of EPS produced by SQR-21 to be used in industry in place of synthetic compounds.     

Purification,structural characterization and antioxidant property of an extracellular polysaccharide from Aspergillus terreus

The marine fungus Aspergillus terreus produces an extracellular polysaccharide, YSS, when grown in potato dextrose-agar medium. YSS was isolated from the fermented liquids using ethanol precipitation, anion-exchange and size-exclusion chromatography. YSS was mainly composed of mannose and galactose in a molar ratio of 7.68:1.00, its average molecular weight was estimated to be about 18.6 kDa. On the basis of chemical and spectroscopic analyses, including one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) spectroscopy, structure of YSS may be represented, at an average, as a backbone of mannan with two types of branches. The mannan backbone is mainly composed of (1→2)-linked α-mannopyranose with small amounts of (1→6)-linked α-mannopyranose residues. The branches consist of terminal β-galactofuranose residues, and disaccharide units of (1→6)-linked α-mannopyranose. The branches are linked to C-6 of (1→2)-linked α-mannopyranose residues of backbone. The antioxidant activity of YSS was evaluated with the scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals in vitro, and the results indicated that YSS had good antioxidant activity, especially scavenging ability on DPPH radicals. The investigation demonstrated that YSS is a novel branched galactomannan with antioxidant activity, and differs from previously described extracellular polysaccharides.     

Optimization and characterization of an extracellular polysaccharide produced byPaecilomyces lilacinus

Summary A new strain of the fungusPaecilomyceslilacinus has been isolated which produces a viscous extracellular polysaccharide in a simple medium. The polysaccharide consists of glucose and galactose moieties. The viscosity of the polysaccharide was unchanged by a range of temperature and pH.     

Optimization and characterization of an extracellular polysaccharide produced byMoniliella pollinis

Summary A yeast strainMoniliellapollinis produces an extracellular highly viscous gum-like polysaccharide of glucan type in a simple mineral medium. Optimum conditions for its production and properties are described. The viscosity decreased after lyophilization.     

Optimization and characterization of an extracellular polysaccharide produced byGlomerella cingulata

Summary A new strain of the fungusGlomerellacingulata has been isolated, which produces an extracellular highly viscous polysaccharide in a simple mineral medium. Optimum conditions for its production and properties are described. The polysaccharide produced was a glucan type. The viscosity remained stable during storage over a period of seven days. Large changes in temperature and pH have no effect on viscosity.     

Identification of the extracellular polysaccharide produced by the snow mold fungus Microdochium nivale

A water-insoluble, extracellular polysaccharide was isolated from the culture medium of the snow mold fungus, Microdochium nivale, that had been cultivated in potato/dextrose broth. The polysaccharide consisted of glucose only. Its Fourier transform infrared spectrum showed a beta configuration of the C1 position of glucose. Linkage analysis of the polysaccharide showed that it had a linear structure of -(14)-linked glucose. The polysaccharide was therefore identified as cellulose. This is the first report of extracellular cellulose occurring in fungi.     

Structure and antioxidant activity of an extracellular polysaccharide from coral-associated fungus, Aspergillus versicolor LCJ-5-4

An extracellular polysaccharide AVP was isolated from the fermented broth of coral-associated fungus Aspergillus versicolor LCJ-5-4. AVP was a mannoglucan with molecular weight of about 7 kDa, and the molar ratio of glucose and mannose was 1.7:1.0. On the basis of detailed one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) spectroscopic analyses, the backbone of AVP was characterized to be composed of (1 → 6)-linked α-d-glucopyranose and (1 → 2)-linked α-d-mannopyranose units. The mannopyranose residues in the backbone were substituted mainly at C-6 by the side chain of (1 → 2)-linked α-d-mannopyranose trisaccharides units. The antioxidant activity of AVP was evaluated with the scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals in vitro, and the results indicated that AVP had good antioxidant activity, especially scavenging ability on superoxide radicals. AVP was a novel extracellular polysaccharide with different structural characteristics from other extracellular polysaccharides and could be a potential source of antioxidant.     

Isolation and characterization of a clay-dispersing polysaccharide produced by the phytopathogenic fungus, Colletotrichum gloeosporioides

The fungus, Colletotrichum gloeosporioides, which is pathogenic to peppers produced an extracellular polysaccharide in liquid culture which possessed clay-dispersing activity. The polysaccharide could bind cationic dyes, Ruthenium Red and Alcian Blue, indicating it to be polyanionic. The polysaccharide dispersed kaolin in water and the dispersion was maintained for more than 7 days at 25 °C. Kaolin dispersion by the polysaccharide was stable from pH 3 to 10 but the addition of divalent metals at 1 mM inhibited half of the dispersion activity comparing to the control. The polysaccharide could disperse bentonite, calcium carbonate and other fine particles but did not possess emulsifying activity.     

Optimization and characterization of a polysaccharide produced by Pseudomonas fluorescens WR-1 and its antioxidant activity

The extracellular polysaccharide produced by a newly isolated strain Pseudomonas fluorescens WR-1 was purified and characterized and its production was optimized using response surface methodology. The results showed that the strain WR-1 produced one kind of EPS that was composed of arabinose, glucose and uronic acid. The molecular weight of the EPS was determined to be 6.78×10(6)Da. The preferable culture conditions for EPS production were pH 7.0, temperature 28°C for 72h with peptone and maltose as best N and C sources, respectively. The model predicted that the maximum EPS production (39.6gL(-1)) was appeared with maltose 48.65gL(-1), Mn(2+) 1118μM and Zn(2+) 901μM. The EPS also showed good H(2)O(2) scavenging activity while moderate free radical scavenging activity and reductive ability were determined. The EPS from WR-1 may be a new source of natural antioxidants with potential value for health, food and industry.     

Structure of extracellular polysaccharide produced by lignin-degrading fungus Phlebia radiata in liquid culture

The extracellular material (EM) produced by the white rot fungus Phlebia radiata cultured in an N-limited liquid medium was studied. Carbohydrate analysis showed maximum concentration of glucose as the major monosaccharide component of EM was found on postinoculation day 9. Beyond day 9 of cultivation the proportion of glucose decreased suggesting that the glucan component of EM had been further metabolized. The analysis of EM at day 9 revealed the presence of the following monosaccharides (in relative %): glucose (62); galactose (16); mannose (13); xylose (4); and fucose (5). The carbohydrate analysis together with the presence of protein in EM corresponds to a mixture of glucan and glycoprotein. Purification by trypsin treatment yielded an enriched glucose-containing extracellular polysaccharide (EPS). Methylation analysis identified EPS as (1-3)-beta-D-glucan highly branched at C-6. The structure of the glucan was confirmed by 13C-NMR spectroscopy. The results suggest that P. radiata's EPS is entangled with a glycoprotein in a complex that makes the extracellular sheath surrounding the hyphae.     

Partial characterization of an extracellular polysaccharide produced by the moderately halophilic bacterium Halomonas xianhensis SUR308

A moderately halophilic bacterium, Halomonas xianhensis SUR308 (Genbank Accession No. KJ933394) was isolated from a multi-pond solar saltern at Surala, Ganjam district, Odisha, India. The isolate produced a significant amount (7.87 g l^?1) of extracellular polysaccharides (EPS) when grown in malt extract–yeast extract medium supplemented with 2.5% NaCl, 0.5% casein hydrolysate and 3% glucose. The EPS was isolated and purified following the conventional method of precipitation and dialysis. Chromatographic analysis (paper, GC and GC-MS) of the hydrolyzed EPS confirmed its heteropolymeric nature and showed that it is composed mainly of glucose (45.74 mol%), galactose (33.67 mol %) and mannose (17.83 mol%). Fourier-transform infrared spectroscopy indicated the presence of methylene and carboxyl groups as characteristic functional groups. In addition, its proton nuclear magnetic resonance spectrum revealed functional groups specific for extracellular polysaccharides. X-ray diffraction analysis revealed the amorphous nature (CI_xrd, 0.56) of the EPS. It was thermostable up to 250°C and displayed pseudoplastic rheology and remarkable stability against pH and salts. These unique properties of the EPS produced by H. xianhensis indicate its potential to act as an agent for detoxification, emulsification and diverse biological activities.     

Isolation, structural characterization and antioxidant activity of a new water-soluble polysaccharide from Acanthophyllum bracteatum roots

ABPS-1, a new water-soluble polysaccharide with molecular weight of 26 kDa and a specific optical rotation of +170° (c 1.0, H₂O), was extracted from the roots of Acanthophyllum bracteatum by warm water and further successively purified through DEAE-cellulose A52 and Sephadex G-100 columns. Monosaccharide analysis revealed that the ABPS-1 was composed of Glc, Gal and Ara with a relative molar ratio of 1.4:5.2:1.0. Its structural features were elucidated by a combination of FT-IR, methylation and GC-MS analysis, periodate oxidation and Smith degradation, partial acid hydrolysis and ¹³C and ¹H NMR spectroscopy. The data obtained indicate that ABPS-1 possessed a backbone of α-(1 → 6)-linked Gal with branches attached to O-2 by α-1 → linked Glc and at O-3 by α-1 → linked Gal and by α-(1 → 3)-linked Ara. The in vitro antioxidant activity showed that ABPS-1 possesses DPPH radical-scavenging activity in a concentration-dependent manner with an EC₅₀ value of 2.6 mg/ml.     

Nematicidal activities of 4-hydroxyphenylacetic acid and oidiolactone D produced by the fungus Oidiodendron sp

Two nematicides, 4-hydroxyphenylacetic acid (4-HPA) (1) and oidiolactone D (2), were isolated from cultures of the fungus Oidiodendron sp., and their structures were identified by spectroscopic analyses. Compound 2 showed nematicidal activities against the root-lesion nematode, Pratylenchus penetrans, and the pine wood nematode, Bursaphelenchus xylophilus. Compound 1 was also active against these two nematodes but to a lesser extent.     

Structural characterization and antioxidant properties of an exopolysaccharide produced by the mangrove endophytic fungus Aspergillus sp. Y16

A homogeneous exopolysaccharide, designated As1-1, was obtained from the culture medium of the mangrove endophytic fungus Aspergillus sp. Y16 and purified by anion-exchange and gel-permeation chromatography. Results of chemical and spectroscopic analyses, including one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) spectroscopy showed that As1-1 was mainly composed of mannose with small amounts of galactose, and that its molecular weight was about 15 kDa. The backbone of As1-1 mainly consists of (1 → 2)-linked α-d-mannopyranose units, substituted at C-6 by the (1 → 6)-linked α-d-mannopyranose, (1→)-linked β-d-galactofuranose and (1→)-linked β-d-mannopyranose units. As1-1 possessed good in vitro antioxidant activity as evaluated by scavenging assays involving 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide radicals. The investigation demonstrated that As1-1 is an exopolysaccharide different from those of other marine microorganisms, and could be a potential antioxidant and food supplement.     

Structural analysis of the extracellular polysaccharide produced by Sphaerotilus natans

An extracellular polysaccharide (EPS) was recovered and purified from the culture fluid of a sheathed bacterium, Sphaerotilus natans. Glucose, rhamnose, and aldobiouronic acid were detected in the acid hydrolysate of EPS by thin-layer chromatography (TLC). The aldobiouronic acid was found to be composed of glucuronic acid and rhamnose by TLC and gas-liquid chromatography analyses of the corresponding neutral disaccharide. The structure of EPS was identified by methylation linkage analysis and nuclear magnetic resonance. Additionally, partial acid hydrolysates of EPS were prepared and put through fast atom bombardment-mass spectrometry to determine the sugar sequence of EPS. The resulting data showed that EPS produced by S. natans is a new gellan-like polysaccharide constructed from a tetrasaccharide repeating unit, as shown below. -->4)-alpha-D-Glcp-(1-->2)-beta-D-GlcA p-(1-->2)-alpha-L-Rha p-(1-->3)-beta-L-Rha p-(1-->.     

Structural analysis of an extracellular polysaccharide produced by Rhodococcus rhodochrous strain S-2

A possibility has been suggested of applying the EPS produced by Rhodococcus rhodochrous strain S-2 (S-2 EPS) to the bioremediation of oil-contaminated environments, because its addition, together with minerals, to oil-contaminated seawater resulted in emulsification of the oil, increased the degradation of polyaromatic hydrocarbons (PAH) of the oil, and led to the dominance of PAH-degrading marine bacteria. To understand the underlying principles of these phenomena, we determined the chemical structure of the sugar chain of S-2 EPS. The EPS was found to be composed of D-galactose, D-mannose, D-glucose, and D-glucuronic acid, in a molar ratio of 1:1:1:1. In addition, 0.8% (w/w) of octadecanoic acid and 2.7% (w/w) of hexadecanoic acid were also contained in its structure. By 1H and 13C NMR spectroscopy, including 2D DQF-COSY, TOCSY, HMQC, HMBC, and NOESY experiments, as well as chemical and enzymatic analyses, the polysaccharide was shown to consist of tetrasaccharide repeating units with the following structure: (see formula in text).     

Characterization of an extracellular polysaccharide produced by a Pseudomonas strain grown on glycerol

A new extracellular charged polysaccharide composed mainly by galactose, with lower amounts of mannose, glucose and rhamnose, was produced by the cultivation of Pseudomonas oleovorans NRRL B-14682 using glycerol as the sole carbon source. Thermal and solid-state NMR analysis showed that this polymer is essentially amorphous, with a glass transition temperature of 155.7 degrees C. The exopolysaccharide aqueous solutions have viscoelastic properties similar to that of Guar gum, but with affinity to salts as a result of its polyelectrolyte character. In addition, the exopolysaccharide has demonstrated good flocculating and emulsifying properties and film-forming capacity. These properties make this polymer a good alternative to more expensive natural polysaccharides, such as Guar gum, in several applications in the food, pharmaceutical, cosmetic, textile, paper and petroleum industries.     

Physical properties of an extracellular polysaccharide produced by Bacillus sp. CP912

AIMS: In this study, some physical properties of Bacillus sp. exo-polysaccharide were investigated. METHODS AND RESULTS: An extracellular polysaccharide was purified by sequential precipitations after homogenization of the diluted culture supernatant of Bacillus sp. CP912. Its physical properties were examined such as lipid emulsifying effect on several vegetable oils and flocculating activity against the activated carbon suspension. The melting point and endothermic calories of the polysaccharide were 128.7 degrees C and 50.864 kCal mol-1, respectively. Its pyrolysis temperature was 284.58 degrees C. The polysaccharide showed high lipid emulsifying activity on oil-water emulsion, against olive, peanut, sunflower and corn oils. It exhibited high flocculating activity as well against activated carbon. CONCLUSIONS: The present findings suggest that the extracellular polysaccharide produced by Bacillus sp. CP912 has a great industrial potential because of its high lipid emulsifying and flocculating activity. SIGNIFICANCE AND IMPACT OF THE STUDY: These data represent a novel Bacillus sp. extracellular polysaccharide possessing high emulsifying and flocculating effects.     

Rheological properties of extracellular polysaccharide, Pestan, produced by Pestalotiopsis sp.

Summary The fluid behaviour of Pestan produced from Pestalotiopsis sp. KCTC 8637P was as a non-Newtonian fluid. The rheological behaviour of Pestan solution was examined by Power-law model, Herschel-Bulkley model and Arrhenius equation. As the result, Pestan solution was pseudoplastic behaviour with yield stress. According to increase of Pestan concentration, its flow index was decreased. Thus, low concentrations of Pestan solution were well exposed pseudoplastic property. Apparent viscosity of 0.2 % Pestan solution was 268.2 cP at 14.3 sec^–1 and was higher about 2.8 times than that of Xanthan gum solution. Apparent viscosity of Pestan solution was stable over a wide pH and was maximum at pH 8. Also, consistency index of Pestan solution was very stable over wide temperature than that of Xanthan gum solution.