海洋红细菌Lentibacter algarum胞外多糖的分离纯化及结构解析

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

摘要:

从青岛潮间带的海水中分离得到的红细菌科细菌Lentibacter algarum的发酵液中提取胞外多糖，对其进行离子交换色谱分离纯化，得到水洗和0.1、0.5、1.0 mol/L NaCl溶液4个洗脱组分。对含量最高的0.1 mol/L NaCl 洗脱组分La0.1进行进一步的凝胶排阻柱层析纯化，得到组分La0.1-1。通过化学测定和高效液相色谱 (HPLC)、高效凝胶渗透色谱法 (HPGPC) 等分析方法对其理化性质、分子量、单糖组成、连接方式及初步结构进行研究。结果表明，La0.1-1总糖含量为66%，平均分子量为12.0 kDa。其单糖组成主要为半乳糖、甘露糖和氨基葡萄糖，比例为Gal：Man：GlcN=1.35:1.1:1.0。对La0.1-1进行气相色谱质谱联用 (GC-MS) 和一维核磁 (1-D NMR) 分析结果显示，La0.1-1的连接方式是以β构型为主，主要存在→2)-Manp(1→，→3)-Galp(1→连接，还存在少量的→4)-Galp(1→和→4)-Manp(1→等连接方式，表明该多糖以直链为主，还存在一定的分支，分支发生在→2)-Manp(1→的O-6位和→3)-Galp(1→的O-4或O-6位。氨基葡萄糖主要为→4)GlcN(1→和末端连接方式。核磁分析还显示La0.1-1存在一定的乙酰基取代，初步判断主要取代在氨基葡萄糖的N-2位上，也可能存在于甘露糖和半乳糖上。本研究是首次对Lentibacter属细菌的胞外多糖进行测定，获得了结构较为新颖的胞外多糖资源，为开发海洋多糖资源提供物质基础。

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.