期刊
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
卷 158, 期 -, 页码 408-419出版社
ELSEVIER
DOI: 10.1016/j.ijbiomac.2020.05.027
关键词
Tibetan kefir grains; Exopolysaccharide (EPS); Immunostimulatory activity
资金
- Fundamental Research Funds for the Central Universities [KYYZ201904, KYYJ201807]
- National Natural Science Foundation of China-Xinjiang Joint Fund [U1903108]
- National Natural Science Foundation of China [31871771, 31571818]
- Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
In this study, three strains of lactic acid bacteria isolated from Tibetan kefir grains, including two strains of Lactobacillus pentosus LZ-R-17 and L. helveticus LZ-R-5, and one strain of Lactococcus lactis subsp. lactis LZ-R-12. The ability of three strains to produce exopolysaccharide (EPS) was tested, and L. pentosus LZ-R-17 was found to have the highest EPS yield. One EPS (R-17-EPS) was isolated from the fermented milk by L. pentosus LZ-R-17 and purified by DEAE-52 anion exchange chromatography. Furthermore, R-17-EPS preliminary structure and macrophage immunomodulatory activity in vitro were investigated. On the basis of the analytical results of ultraviolet-visible spectrum, Fourier transform-infrared spectrum, monosaccharide composition analysis and one-dimensional and two-dimensional nuclear magnetic resonance (NMR) spectra, R-17-EPS was found to have an average molecular weight of 1.20 x 106 Da and was composed of galactose and glucose residues with amolar ratio of 1.00:3.15. NMR analysis revealed that the R-17-EPSwas a linear hetero-galactoglucan containing repeating units of -> 2)-alpha-D-Galp-(1 -> 4)-beta-D-Glcp-(1 -> 4)-beta-D-Glcp-(1 -> 4)-beta-D-Glcp-(1 ->. In addition, R-17-EPS could effectively enhanced the proliferation, phagocytosis, nitric oxide and cytokines production of RAW264.7 cells, suggesting that R-17-EPS had potent immunostimulatory activity and could be explored as immunomodulator in functional food and/or medicine fields. (c) 2020 Elsevier B.V. All rights reserved.
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