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

Abstract:

[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%.

Key words:Biological soil crust, Exoploysaccharide, Bioflocculant activity, Purification