Isolation of Feed Additive Xylanase Producing Bacillus Strain and Partial Characterization of the Enzyme

The aerobic and xylanolytic bacterium Bacillus sp. XbO was isolated from soil sample. The results of 16S rDNA sequence comparisons indicated that Bacillus sp. XbO was closely related to Bacillus pumilus and Bacillus safensis with 98% levels of sequence homology. The optimum temperature and pH values of the enzyme were found to 60 ºC and 6.0 respectively. The residual activities of the enzyme after pre-incubation at 70 ºC and 11.0 pH value for 30 min, were 86 and 79% respectively. Maximum enzyme production was observed after an incubation period of 24 hours, at 37 ºC. The enzyme activity was increased 173, 167, 144, 141, 133, 126, and 112% in the presence of MnCl2, CoCl2, ZnCl2, MgCl2, CaCl2, EDTA, and FeCl3 (5 mM) respectively. On the other hand, xylanase activity was strongly inhibited in the presence of HgCl2. The specific activities of crude and purified enzymes were 27.6 and 113.8 U/mg proteins, respectively. Electrophoretic analysis showed the presence of single band having molecular weight of about 81 kDa. These properties of the enzyme indicated that it could be used as an enzyme supplement for animal fee