A strain of Bacillus subtilis AF 17 with high exopolysaccharide (EPS) production ability was isolated and identified based on morphological and physiological characteristics and phylogenetic analysis of 16S rDNA sequences. EPS was isolated from the strain fermentation broth by alcohol precipitation and gel-filtration chromatography. Its structural characteristics were investigated and elucidated by methylation analysis, gas chromatography mass spectrometry and nuclear magnetic resonance spectroscopy. Based on the obtained data, the EPS was found to be a levan containing a backbone of 6-substituted beta-fructoses, with a low grade of branching at position 1 (linear/branched ratio 20:1). Levan showed a molecular weight of about 20 MDa. The antioxidant activity of this biopolymer was studied and revealed that levan showed an interesting 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging capacity (IC50 levan = 1.42 mg/mL), reducing power, and also a strong total antioxidant activity. Overall, the results suggest that levan is a promising source of natural antioxidants and can be used as additive in food and pharmaceutical preparations.

exopolysaccharides, purification, Structural characterization, Antioxidant activity, Bacillus subtilis AF17

• Compound ID: 14424
  

  b-D-Fruf-(2-1)-+ | -6)-b-D-Fruf-(2-6)-{{{-b-D-Fruf-(2-6)-}}}/n=19/-b-D-Fruf-(2-

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  Structure type: polymer chemical repeating unit ; 20000000
  Trivial name: levan
  Compound class: EPS, polyfructan
  Reference(s) to other database(s): GTC:G94003ED
  
   
  
  Bacillus subtilis AF17
  CSDB ID 32067 (all data & tools)