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 6.23x10(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 degrees 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.

characterization, structural analysis, purification, Antioxidant activity, Leuconostoc pseudomesenteroides dextran

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

[*]OC[C@H]1O[C@H]([*])[C@H](O)[C@@H](O)[C@@H]1O

162.141 g/mol (C₆H₁₀R₂O₅, R = next and previous repeats, not counted in mol weight)

An exopolysaccharide (EPS)-producing bacterial strain L3 was isolated from Hubei sausage and identified as Lactobacillus sakei via morphological, physiological, biochemical and 16S rDNA analysis. FT-IR spectroscopy and NMR revealed that L3 EPS was a dextran containing d-glucose residues with α-1,6 glycosidic linkage. Rheological studies showed that it had high viscosity at high concentration, low temperature, and acidic pH (pH 3.0). Scanning electron microscopy of the L3 dextran demonstrated a porous and branched morphology, and atomic force microscopy showed lumps of varying height on the rough surface of the L3 EPS polymer. The EPS was thermally stable up to 272 degrees C and could coagulate sucrose-supplemented milk. Together, these results suggested that L3 EPS might have potential applications in food processing and other areas.

exopolysaccharide, Lactobacillus sakei, Dextran, Structural characterization

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
	aDGlcp	97.7	71.4	73.4	69.5	70.2	65.6


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
	aDGlcp	4.91	3.51	3.65	3.45	3.84	3.69-3.92


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
	aDGlcp	97.7/4.91	71.4/3.51	73.4/3.65	69.5/3.45	70.2/3.84	65.6/3.69-3.92

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

[*]OC[C@H]1O[C@H]([*])[C@H](O)[C@@H](O)[C@@H]1O

162.141 g/mol (C₆H₁₀R₂O₅, R = next and previous repeats, not counted in mol weight)