Azotobacter chroococcum produces appreciable amounts of exocellular polysaccharide. Produced by A. chroococcum strain NRRL B-14341 are at least two distinct polysaccharides which can be separated by ion-exchange chromatography on DEAE-Sephadex A-25. Exopolysaccharide I (EPS-I) consists of rhamnose, mannose, and galactose in the molar ratios of 1:2:2, along with a trace of glucose. EPS-I also contains pyruvic acetal and acetic ester groups. Exopolysaccharide II (EPS-II) consists mainly of mannuronic acid, with much smaller proportions of guluronic acid. Acetic ester groups are also present in EPS-II. Methylation analysis of reduced EPS-II shows it to be (1→4)-linked, and 13C-nuclear magnetic resonance spectroscopy indicates that it is mainly (1→4)-β-d-mannuronan. EPS-II is evidently a low-guluronate form of alginate. Batch-to-batch variation was observed in the relative amounts of the two polysaccharides, the acetyl and pyruvic contents of EPS-I, and the degree of acetylation of EPS-II.

structure, exopolysaccharide, Azotobacter chroococcum

• Compound ID: 845
  

  -4)-b-D-ManpA-(1-

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  Structure type: homopolymer
  Trivial name: alginate, mannuronan
  Compound class: EPS, polysaccharide
  Reference(s) to other database(s): GTC:G79479XA, GlycomeDB:25662
  
   
  
  Azotobacter chroococcum NRRL B-14341
  CSDB ID 27138 (all data & tools)