title: Bioactive exopolysaccharides from a S. thermophilus strain: Screening, purification and characterization.
abstract: A lactic acid bacteria strain AR333 with high-production of exopolysaccharides (EPS) was screened out from 350 bacteria strains isolated from naturally fermented dairy products. It was identified as Streptococcus thermophilus by morphological observation, physiological and biochemical characteristics, and 16S rDNA sequence determination. The EPS from AR333 were purified through DEAE-Sepharose Fast Flow and Sepharose CL-6B, and the purified fraction was designated as EPS333. In vitro test showed that EPS333 could stimulate macrophage RAW 264.7 to release NO significantly (p<0.05). The further work tried to elucidate the structural features of EPS333 via FT-IR spectrum, high-performance anion exchange chromatography (HPAEC) and high-performance size exclusion chromatography (HPSEC). The results showed that EPS333 was a pure neutral polysaccharide with monosaccharide composition of galactose and glucose in a molar ratio of 6:5. A certain amount of acetyl groups might exist in EPS333 according to the FT-IR spectrum. The molecular weight (Mw) was estimated to be 332 kDa. Current study suggested that the lactic bacteria strain AR333 could be a potential source of immunoregulatory polysaccharide.
authors.affiliation: School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ren
authors.affiliation: School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Xia
authors.affiliation: School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Guangqiang
authors.initials: G
authors.lastname: Wang
authors.affiliation: School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
authors.forename: Song
authors.initials: S
authors.lastname: Zhu
authors.affiliation: School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China. Electronic address: ailianzhong@163.com.
authors.forename: Lianzhong
authors.initials: L
authors.lastname: Ai
mesh_terms: D000818:Animals; D005285:Fermentation; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008970:Molecular Weight; D009005:Monosaccharides / Q000032:analysis; D009569:Nitric Oxide / Q000096:biosynthesis; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D000067996:RAW 264.7 Cells; D048249:Streptococcus thermophilus / Q000302:isolation & purification / Q000378:metabolism*; D014783:Viscosity
chemical_list: D009005:Monosaccharides; D011135:Polysaccharides, Bacterial; D009569:Nitric Oxide
keywords: Exopolysaccharides; Streptococcus thermophilus; Viscosity