Purification of xylanase (EC:3.2.1.8) from Bacillus stearothermophilus (ATCC 12980) and study of the effect's on xylan degradation

Xylan the major portion of the hemicellulose of plant cell walls are heterogeneous polysaccharides. Xylanases (EC: 3. 2. 1. 8) are enzymes obtained from different species of microorganisms that degrade the xylosidic linkages of xylan’s backbone producing xylose with other monoresidues. In this study xylanase enzyme was purified from culture supernatant of Bacillus stearothermophilus (ATCC 12980) by ammonium sulfate precipitation، gel filtration on sephadex G-100 followed by ion exchange chromatography on DEAE-cellulose. In DEAE- cellulose column chromatography، three protein peaks F-1a، F-1b and F-1c were appeared. Among these peaks، only F-1b showed xylanase activity and the degree of purification attained 63. 09 fold. The specific activity and purification fold of the purified xylanase was 87. 7 U/mg of protein and 17. 45، respectively. The enzyme gave maximum activity against xylan as substrate at pH 7. 0 and temperature at 60°C. In paper chromatography xylose was detected as the hydrolysis products of oat-spelt xylan by the xylanase at 16 h. These results indicate that xylanase of Bacillus stearothermophilus (ATCC 12980) was endoxylanase. In conclusion، these data suggested that purified xylanase can be suitable for industrial applications.