beta-mannanase and xylanase of Bacillus subtilis 5H active for bleaching of crude pulp

A bacterial strain, 5H was isolated as a utilizer of locust bean gum (LBG) from soil in Chiang Mai, Thailand, and identified as Bacillus subtilis. Str ain 5H produced beta-mannanase and xylanase, which were purified to homogen eity from the culture filtrate by ion exchange chromatography and gel filtr ation. The molecular weights of beta-mannanase and xylanase were found to b e 37,000 and 26,000 by sodium dodecyl sulfonate polyacrylamide gel electrop horesis, respectively. The enzymatic properties of both were determined. Ma nnanase hydrolyzed LEG and konjak mannan endwisely, to a final hydrolytic d egree of 15% and 21%, respectively, and the main products of both were disa ccharides. Xylanase hydrolyzed larch wood xylan and oat spelt xylan, to a f inal hydrolytic degree of 19% and 38%, respectively, and produced mainly di saccharides. This culture filtrate (4.9 units/ml beta-mannanase and 3.2 uni ts/ml xylanase), a mixture of purified beta-mannanase (4.9 units/ml) and xy lanase (3.2 units/ml), and purified xylanase (3.2 units/ml) bleached crude paper pulp from 30% to 38% brightness, and xylanase was found to be more ef fective for paper-bleaching than beta-mannanase.