The Research On Microbial Diversity Of Moderately Halophilic Bacteria From Dabancheng Saline Lake In Xin Jiang And Studies On Purifiction And Properties Of Î'-Mannanase From Athelia Rolfsii (Curzi) Tu Et Kimbrough

The moderately halophilic bacteria, as a type microbial resource,were used in many aspects. From the samples of Da Bancheng saline lake in XinJiang, 17 strians were isolated. 11 strains of them were Gram-positive and 6strains were Gram-negative. General morphology characteristic and 16S rDNAsequence tests were finished in Institute of Microbiology, Chinese Academy ofSciences. Based on morphological properties and 16S rDNA sequences, thesestrains belonged to genera Halomonas,Bacillus,Salinicoccus,Halobacillus,Marinococcus,Thalassobacillus,Nesterenkonia.Most of them belonged togenera Halomonas.After cultivating in liquid medium for 5 days, an extra cellularβ-mannanase from Athelia rolfsii strain CBS191.62 was purified 15.1-fold toelectrophoretic homogeneity by ammonium sulfate precipitation, DEAESepharose Fast Flow chromatography, Hydroxylapatite chromatography andrefrigeration crystal. The molecular mass of the enzyme was estimated to be 15kDa by SDS-PAGE and the pI of 2.95 was estimated by IEF-PAGE.The enzymewas optimally active at pH 5 and 30℃and showed stability at pH range of 4.2to 6.8 at the temperature below 40℃. The enzyme was strongly inhibited byZn²⁺,Fe³⁺,Co²⁺,Hg²⁺ and partly inhibited by Mg²⁺,Al³⁺ and slight inhibitedby Li⁺,Mn²⁺,Ca²⁺.