PRODUCTION OF XYLANASES BY BACILLUS-POLYMYXA USING LIGNOCELLULOSIC WASTES

Production of xylanolytic enzymes with no detectable cellulase activit y was investigated using two strains of Bacillus polymyxa. The optimum pH and temperature for activities of the two xylanases ranged from 6. 0 to 7.0 and from 45 to 50 degrees C, respectively. The highest titres of xylanase, up to 24 nKat ml(-1) were produced within 36 and 42 h, r espectively in shake flask cultures at 30 degrees C. Enzyme production showed a cell growth associated profile. One of two strains, B. polym yxa CECT 153 was chosen for further detailed study. Numerous carbohydr ates were examined for their ability to induce xylanase. It was found that xylan or xylan containing substrates, such as wheat straw, induce d maximum and comparable levels of xylanase, while pure cellulose (avi cel, alpha-cellulose) and the easily metabolisable sugars (glucose, su crose) did not improve xylanase synthesis. Low levels of constitutive enzyme were produced as evidence from the culture medium without carbo n source addition. Among various nitrogen sources tested, yeast extrac t was optimal for the production of xylanase. (C) 1998 Elsevier Scienc e B.V.