Isolation, structural characterization and immunological activity of an exopolysaccharide produced by Bacillus licheniformis 8-37-0-1
2010
Liu, Chunhui | Lu, Juan | Lü, Lili | Liu, Yuhong | Wang, Fengshan | Xiao, Min
A strain of Bacillus licheniformis 8-37-0-1 with high exopolysaccharide (EPS) production ability was isolated and identified based on morphological and physiological characteristics and phylogenetic analysis of 16S rDNA sequences. A new type of EPS was isolated from the strain fermentation broth by enzymolysis, isopropanol precipitation, anion-exchange, and gel-filtration chromatography. The new EPS was determined as homogeneous, with a molecular weight of 2.826×10⁴, as determined by High-Performance Size-Exclusion Chromatography Multi-Angle Laser Light Scattering analysis. Its structural characteristics were investigated and elucidated by methylation analysis, partial acid hydrolysis, gas-liquid chromatography mass spectrometry, Fourier transform infrared, and nuclear magnetic resonance spectroscopy. Based on obtained data, the EPS was found to be a levan containing a (2→6)-linked backbone with a single β-d-fructose at the C-1 position every seven residue, on average, along the main chain. Preliminary in vitro tests revealed that EPS could significantly stimulate the proliferation of spleen lymphocyte.
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