类芽孢杆菌BD3526在无氮固体培养基上产胞外多糖的研究

为了研究Paenibacillus bovis sp.nov BD3526在无氮培养基上产的胞外多糖的结构和生物活性,本文制得了其在无氮培养基平板上分泌的胞外多糖,并用离子交换层析法对此胞外多糖进行分离纯化,得到了一个主要组分的纯品（F1）;凝胶渗透色谱（GPC）的结果显示F1的分子量是3.76×107Da,用红外光谱（FT-IR）和核磁共振氢谱（1H NMR）表征其化学结构,结果表明F1是直链的左聚糖;热重分析（TGA）和差示扫描量热法（DSC）的结果表明左聚糖具有良好的热稳定性;动态光散射仪（DLS）测定其在水溶液中形成的聚集体的粒径约为163.2 nm,而透射电镜（TEM）照片表明其在水溶液中呈紧实的球型,粒径在50¹00 nm;最后采用细胞实验评价其免疫增强作用,体外实验结果表明此左聚糖在低浓度时即可显著促进脾细胞的增殖,具有很强的免疫增强活性。此左聚糖可以作为免疫增强剂应用于功能性食品领域。 

Study on the exopolysaccharides produced by Paenibacillus bovis sp.nov BD3526 in nitrogen-free solid culture medium

This study was aimed to investigate the structure and bioactivities of exopolysaccharides produced by Paenibacillus bovis sp.nov BD3526 in nitrogen-free solid culture medium. The exopolysaccharides were prepared, and then separated and purified by DEAE-sepharose fast flow and one main component was obtained ( F1) .Its molecular weight and molecular weight distribution was determined by gel permeation chromatography while its chemical structure was characterized by FT-IR and1 H NMR, indicating F1 was linear levan with ultrahigh molecular weight of 3.76 × 107 Da. It had good thermal stability, which was analyzed by thermogravimetric analysis ( TGA) and differential scanning calorimetry ( DSC) . DLS result indicated the particle size of its aggregates in aqueous solution was 163.2 nm while its conformation was characterized as compact sphere ( 50~ 100 nm) by TEM.Finally, its immunological activity was evaluated by an in vitro method and the result demonstrated F1 could significantly stimulate the proliferation of spleen cells, indicating it can be a potential natural immunomodulator. This levan could be an immunoenhancer to be used in functional food field.