Purification and Biochemical Characterization of Xylanases from Bacillus Pumilus and their Potential for Hydrolysis of Polysaccharides

Extracellular xylanases free of cellulase produced by the alkalophilic bacteria Bacillus pumilus was purified to homogeneity throughout the precipitation with (NH 4 ) 2 SO 4 , Q-Sepharose chromatography and characterized. The purified xylanases were proteins, with molecular mass ~14 kDa (Xyl 1), ~ 35 kDa (Xyl 2) and ~ 60 kDa (Xyl 3) as determined by SDS-PAGE. The optimal temperature and pH for the action of the enzyme were at 50 o C and 7 respectively. They exhibited thermal stability over a range of 20 to 40 o C at pH-7 and has retained 85 % at 60 o C. The activity strongly inhibited by 10 mm of Hg 2+ , SDS and Fe 2+ . The xylanase exhibited Km and Vmax values were 4.0 mg/ ml, 5000 μmol/ min/ mg protein (Xyl 1) as well as 3.5 mg /ml, 3448 μmol/ min/ mg of protein (Xyl 2) for oatspelt xylan.