Purification and structural elucidation of exoploysaccharide from a new marine bacterium Lentibacter algarum ZXM100T

Abstract:

Exopolysaccharide La0.1-1 was extracted from the broth of a marine bacterium Lentibacter algarum ZXM100T isolated from the seawater in the coastal region of Qingdao and purified by Q Sepharose Fast Flow ion-exchange chromatography and Superdex 75 gel-permeation chromatography. Its physiochemical properties and primary structural characters were investigated by chemical analysis together with high performance liquid chromatography (HPLC), high performance gel permeation chromatography (HPGPC) and gas chromatography and mass spectrometry (GC-MS). The results show that the total sugar content of the exoploysaccharide La0.1-1 was about 66% with an average molecular weight at 12.0 kD. La0.1-1 is mainly composed of Gal, Man, GlcN at the ratio of 1.35:1.1:1.0. Results of GC-MS and NMR demonstrate that the exopolysaccharide La0.1-1 mainly exists with the β configuration. The primary linkage styles are →2)-Manp(1→ and →3)-Galp(1→ with a small amount of →4)-Galp(1→ and →4)-Manp(1→ linkages. The linkage mode of GlcN is →4)GlcN(1→ and terminal linkage. The exopolysaccharide has mainly a linear sructure with a few branches linked to O-6 of →2)-Manp(1→ and O-4 or O-6 of →3)-Galp(1→. 1D-NMR data also revealed that La0.1-1 is substituted by certain acetyl; the acetyl is mainly linked to N-2 of GlcN. The exopolysaccharides of the bacterium of Lentibacter genus is reported for the first time, and an exopolysaccharide with novel structure was obtained, which enriched marine polysaccharide resources.

Key words:marine bacterium, exopolysaccharides, purification, physical and chemical properties, structure analysis