Chem. J. Chinese Universities ›› 2004, Vol. 25 ›› Issue (7): 1288.

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Isolation, Purification and Structural Elucidation of EPS-Ⅰ,an Extracellular Polysaccharide from Enterococcus durans

GU Xiao-Mei1, WU Hou-Ming2, MA Gui-Rong1   

  1. 1. State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China;
    2. State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
  • Received:2003-05-16 Online:2004-07-24 Published:2004-07-24

Abstract: The rough crystal of exopolysaccharide produced by Enterococcus durans, a strain of lactic acid bacteria screened from the intestine of a cock in our laboratory, was purified by CM-cellulose column chromatography, DEAE-Sephadex A-25 ionexchange and Sephadex G-100 gel chromatography to give EPS-Ⅰ. The EPS-Ⅰ was eluted as a single peak in HPLC analysis, indicating the homogeneity of EPS-Ⅰ and free from low-molecular-weight polysaccharides. The molecular weight of the EPS-Ⅰ was determined as 42 000 by the light scattering method. The result of its elemental analysis was C 41.08% and H 7.23% without the elements of N, P and S. Monosaccharide analysis showed that it was composed of Glc and Man in a molar ratio of 4∶1. Sugar composition analysis, methylation analysis and 1H and 13C NMR spectroscopy revealed that the EPS-Ⅰ was composed of pentasaccharide repeating units. The sequence of sugar residues was determined by using two-dimensional NMR, including heteronuclear multiple-bond correlation(HMBC) and nuclear overhauser effect spectroscopy(NOESY). The structure of the pentasaccharide repeating unit of EPS-Ⅰ was given, a new excellular polysaccharide from lactic acid bacterium compared with other EPSs was reported.

Key words: Enterococcus durans, EPS-Ⅰ, Extracellular polysaccharide, Purification

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