【Abstract】 One Gram-positive bacteria,Bacillus sp.strain BG-CSN,was isolated from the muds with hypersaline and alkaline water at the beach of Banger Soda Lake in Tibet,China.After cultivating in liquid medium for 48 hours,an extracellular α-amylase AmyBGC from the strain BG-CSN was purified 23-fold reaching to electrophoretic homogeneity by sequentially ammonium sulfate precipitation,Octyl-Sepharose CL-4B column chromatography,DEAE-Sepharose Fast Flow chromatography,DEAE-Toyopearl 650M chromatography and Sephadex G-100 chromatography.The enzyme had a molecular mass of 87 kD estimated by SDS-PAGE.The enzyme was optimally active at pH 10.5 and 52.5℃ and showed stability at pH range of 5.0 to 11.5 at the temperature below 35℃. The enzyme activity was inhibited by Hg+ and Fe 3+.The activity was not prevented at all by chelating reagents EDTA and SDS at high concentrations.This enzyme efficiently hydrolyzed starch to yield a series of maltooligosaccharides,including maltose after completion of the reaction.These results indicate that AmyBGC is classified as a liquefying endo-1,4-D-α-amylase(EC-3.2.1.1).更多还原