Chiang Mai Journal of Science

Cellulase and xylanase producing bacteria, Bacillus amyloliquefaciens CX1 and Bacillus subtilis B4, were isolated from horse feces and cow’s rumen fluid. Both enzymes were purified, characterized, and determined their molecular weight. The molecular weight of purified cellulase and xylanase of B. amyloliquefaciens CX1 was found to be 53 kDa and 26 kDa when cellulase and xylanase produced from B. subtilis B4 was estimated to be 46 and 23 kDa, respectively. Both cellulases exhibited their thermostability in wide range of 20-80°C and were stable over a broad range of pH 5-10. While both xylanases showed thermostability ranging 20-50°C, and were stable over a broad pH range of 4.0-9.0. Cellulase and xylanase activities were stimulated by Fe3+, in contrary both enzymes’ activities were strongly inhibited by 10 mM Mn2+ and Cu2+. Xylanase from B. amyloliquefaciens CX1 showed the highest hydrolysis activity on various pretreated lignocellulosic substrates including rice straw, corn stover, paragrass and napier grass to total reducing sugar by 2.23, 3.52, 2.72 and 2.39 mg/ml, respectively. Furthermore, cellulase produced from B. subtilis B4 showed maximum release of reducing sugar from napier grass (0.72 mg/ml), followed by paragrass (0.58mg/ml), and rice straw (0.45mg/ml). Cellulase and xylanase produced from B. amyloliquefaciens CX1 and B. subtilis B4 could also be considerable biotechnological interest particularly in fermented food process for cattle feed since the enzymes showed a dramatically stability over broad pH and temperature range.