PURIFICATION AND PROPERTIES OF BETA-1,4-XYLANASES 2 AND 3 FROM AEROMONAS-CAVIAE W-61

A system of multiple xylanase enzymes was detected in the culture supernatant of Aeromonas caviae W-61. Among the detected xylanases, two beta-1,4-xylanases (1,4-beta-D-xylan xylanohydrolases, EC 3.2.1.8), designated xylanases 2 and 3, have been purified to homogeneity, by using ultrafiltration, ammonium sulfate precipitation, DEAE-Toyopearl 650M, CM-Sephadex C-50, and high-pressure liquid chromatographies. Endoxylanase 2 was a basic protein of 41 kDa, and endoxylanase 3 was an acidic protein of 58 kDa. The two xylanases had different pH and temperature optima, as well as thermal stabilities. The two purified enzymes had no activity on beta-1,3-xylan, cellulose, carboxymethyl cellulose, or water-soluble starch. Various xylo-oligosaccharides such as xylotriose, xylotetraose, xylopentaose, xylohexaose, and higher oligosaccharides were formed, and only a small amount of xylobiose was detected as the hydrolysis products of oat spelt xylan by endoxylanase 2. Endoxylanase 3 released higher xylo-oligosaccharides as main products with very small amounts of xylotetraose and xylopentaose.