红树林内生真菌胞外多糖的分离、化学组成和结构特征

Isolation,chemical components and structural characterizations analysis of extracellular polysaccharides produced by the mangrove endophytic fungi

目的对分离自广东红树林海桑深层根泥内生真菌PJX-2和分离自海南红树林根泥内生真菌Penicilliumsp.H-25-02的胞外多糖进行研究。方法利用乙醇沉淀法、Q Sepharose Fast Flow离子交换柱色谱和Sephacryl S-100凝胶柱色谱对菌株发酵液中的胞外多糖进行分离纯化;通过高效凝胶渗透色谱(HPGPC)、PMP柱前衍生高效液相色谱(HPLC)、红外光谱(IR)及气质联用色谱(GC-MS)等方法,研究胞外多糖的化学组成和结构特征。结果从2株真菌发酵液中分离纯化获得4个多糖,qw-2,qs-3a,jxw-2和jxs-2,它们的分子量分别为12.22、22.87、5.63和9.70kDa;这4个多糖主要由甘露糖组成,jxw-2和qw-2还含少量葡萄糖,qs-3a还含少量半乳糖和半乳糖醛酸;jxw-2和jxs-2中均含有末端Man,1,2)-Man,1,6)-Man和1,2,6)-Man,而jxw-2还含有少量1,3)-Glc;qw-2和qs-3a中均含有末端Man,1,2)-Man和1,2,3)-Man,而qw-2还含有1,2,6)-Man和1,4)-Glc,qs-3a还含有1,4)-Man,以及末端Gal及1,6)-Gal。结论首次分离和分析了4个红树林内生真菌胞外多糖,它们的化学特征不同,qs-3a糖链中含有罕见的1,6)-Gal。

Objective To investigate the extracellular polysaccharides from the mangrove endophytic fungi PJX-2 and Penicilliurn sp. H-25-02. Methods The extracellular polysaccharides were isolated from the culture medium of the mangrove endophytic fungi using ethanol precipitation, Q-Sepharose Fast Flow anion-exchange and Sephacryl S-100 gel-permeation chromatography. The chemical compositions and structural characteristics of the extracellular polysaccharides were studied by high gel permeation chro- matography （HPGPC）, pre-column high performance liquid （HPLC） derivation, Fourier-transform in- frared （IR） spectroscopy and gas chromatography-mass spectrometry （GC-MS）. Results Four polysac- charides, qw-2, qs-3a, jxw-2 and jxs-2 were obtained from the culture medium of the two strains of mangrove endophytic fungi, and their molecular weights were about 12. 23, 22.88, 5.64 and 9.71 kDa, respectively. Four polysaccharides were mainly composed of mannose. Minor amounts of glucose were also found in jxw-2 and qw-2, and small amounts of galactose and galacturonic acid were detected in qs- 3a. Methylation analysis showed that the extracellular polysaceharides ixw-2 and ixs-2 were main[y composed of terminal Man, 1,2）-Man, 1,6）-Man and 1,2,6）-Man, with small amounts of 1,3）-Glc for j xw-2. The extracellular polysaccharides qw-2 and qs-3a consisted of terminal Man, 1,2）-Man and 1,2, 3）-Man. Furthermore, qw-2 with 1,2,6）-Man and 1,4）-Glc, and qs-3a with 1,4）-Man, terminal Gal and 1,6）-Gal. Conclusion The four extracellular polysaccharides from the mangrove endophytic fungi PJX-2 and Penicillium sp. H-25-02 were firstly isolated and investigated. The four extracellular poly- saccharides had different chemical characteristics, and qs-3a contained rare sugar units of 1,6）-Gal.