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

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

【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 k D。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 k D的多糖组分EPS-I。

[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 k D. The bioflocculant activity in kaolin system of exopolysaccharide was 80.4%. [Conclusion] The average molecular weight of the exoploysaccharide EPS-I was 575 k D. The bioflocculant activity in kaolin system of exopolysaccharide was 80.4%.