沙漠生物结皮芽孢杆菌产胞外多糖的纯化及其絮凝性的研究

【目的】以新疆古尔班通古特沙漠的生物结皮为样品，通过培养、筛选、分离得到一株高产胞外多糖(EPS)的菌株XJ-27，对XJ-27菌株所产的胞外多糖进行分离纯化，并对其絮凝性进行研究。【方法】利用DEAE sepharose CL-6B阴离子层析和Sephadex G100凝胶层析的方法对胞外多糖进行纯化，通过紫外分析方法和高效凝胶渗透色谱进行纯度的测定，利用高效凝胶渗透色谱法(HP-GPC)测定其分子量，以高岭土为体系对其絮凝性进行研究。【结果】利用层析分离的方法共得到2个胞外多糖的组分，对其中一个组分进一步纯化，得到组分EPS-I。结果表明，EPS-I纯度较高，分子量为575 kD。同时对胞外多糖的絮凝性进行了研究，结果表明该胞外多糖对高岭土为体系的絮凝率为80.4%。【结论】菌株XJ-27产胞外多糖，其胞外多糖具有絮凝性，对该胞外多糖进行分离纯化后，得到分子量为575 kD的多糖组分EPS-I。

Purification and bioflocculant activity characterization of exoploysaccharide from Bacillus thuringiensis in sand biological soil crust

[Objective] By screening from sand biological soil crusts in Gurban Tonggut Desert, Xinjiang, China, a novel strain Bacillus thuringiensis XJ-27 with high yield of exopolysaccharide (EPS) was obtained. Exopolysaccharide was purified from XJ-27 and its bioflocculant activity in kaolin system was studied. [Methods] Purification of exopolysaccharide was carrried out by DEAE sepharose CL-6B ion-exchange chromatography and Sephadex G100 gel-permeation chromatography. Its physiochemical properties and molecular weight were investigated by chemical analysis and high performance liquid chromatography (HPLC) as well. The bioflocculant activity was studied in kaolin system. [results] Exopolysaccharide EPS-I was purified with DEAE sepharose CL-6B ion-exchange chromatography and Sephadex G100 gel-permeation chromatography. The average molecular weight of the exoploysaccharide EPS-I was 575 kD. The bioflocculant activity in kaolin system of exopolysaccharide was 80.4%. [Conclusion] The average molecular weight of the exoploysaccharide EPS-I was 575 kD. The bioflocculant activity in kaolin system of exopolysaccharide was 80.4%.