Purification and properties of β-1,4-xylanase from Aeromonas caviae W-61

Aeromonas caviae W-61, which was isolated from water samples at the Faculty of Agriculture, Tohoku University, produced β-1,4-xylanase (1,4-β-D-xylan xylanohydrolase; EC 3.2.1.8) extracellularly. The xylanase was purified to homogeneity by using DEAE-Sephadex A-50, CM-Sephadex C-50, and Sephadex G-100 column chromatographies. The molecular weight of the purified enzyme was estimated to be 22,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isoelectric point of the enzyme was 9.2. The optimal pH and temperature for the activity of the enzyme were 7.0 and 55°C, respectively. The enzyme was stable at pH 7.0 at temperatures of up to 50°C. As enzymatic products, various xylo-oligosaccharides such as xylobiose, xylotriose, xylotetraose, and xylopentaose were formed, and only a small amount of xylose was detected. The purified enzyme did not hydrolyze starch, cellulose, carboxymethylcellulose, or β-1,3-xylan.